Microchip dsPIC33EV256GM003 Manual

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High-Speed PWM

Section 14. High-Speed PWM

HIGHLIGHTS

This section of the manual contains the following major topics:

14.1 Introduction .................................................................................................................. 14-2

14.2 Features....................................................................................................................... 14-2

14.3 Control Registers ......................................................................................................... 14-3

14.4 Architecture Overview................................................................................................ 14-24

14.5 Module Description .................................................................................................... 14-27

14.6 PWM Operating Modes.............................................................................................. 14-33

14.7 PWM Generator......................................................................................................... 14-71

14.8 PWM Trigger.............................................................................................................. 14-87

14.9 PWM Interrupts.......................................................................................................... 14-98

14.10 PWM Fault Pins ......................................................................................................... 14-99

14.11 Special Features ...................................................................................................... 14-105

14.12 PWM Output Pin Control...........................................................................................14-111

14.13 Immediate Update of PWM Duty Cycle ................................................................... 14-113

14.14 Power-Saving Modes............................................................................................... 14-114

14.15 External Control of Individual Time Base(s)............................................................. 14-114

14.16 Application Information ............................................................................................ 14-115

14.17 Register Map............................................................................................................ 14-126

14.18 Related Application Notes........................................................................................ 14-127

14.19 Revision History ....................................................................................................... 14-128

dsPIC33E/PIC24E Family Reference Manual

14.1 INTRODUCTION

This section describes the High-Speed Pulse-Width Modulator (PWM) module and its

associated operational modes. The High-Speed PWM module in the dsPIC33E/PIC24E

device family supports a wide variety of PWM modes and is ideal for power

conversion/motor control applications. Some of the common applications include:

• AC-to-DC converters

• DC-to-DC converters

• AC and DC motors: BLDC, PMSM, ACIM, SRM, etc.

• Inverters

• Battery chargers

• Digital lighting

• Uninterrupted Power Supply (UPS)

• Power Factor Correction (PFC) (e.g., Interleaved PFC and Bridgeless PFC)

14.2 FEATURES

The High-Speed PWM module consists of the following major features:

• Up to seven PWM generators, each with an individual time base

• Two PWM outputs per PWM generator

• Individual period and duty cycle for each PWM output

• Duty cycle, dead time, phase shift and frequency resolution equal to the system clock

source (TOSC)

• Independent fault and current-limit inputs for up to 14 PWM outputs

• Redundant Output mode

• Independent Output mode (this feature is not available on all devices)

• Push-Pull Output mode

• Complementary Output mode

• Center-Aligned PWM mode

• Output override control

• Special Event Trigger

• PWM capture feature

• Prescaler for input clock

• ADC triggering with PWM

• Independent PWM frequency, duty cycle and phase shift changes

• Leading-Edge Blanking (LEB) functionality

• Dead time compensation

• Output clock chopping

Note: This family reference manual section is meant to serve as a complement to device

data sheets. Depending on the device variant, this manual section may not apply to

all dsPIC33E/PIC24E devices.

Please consult the note at the beginning of the “High-Speed PWM” chapter in the

current device data sheet to check whether this document supports the device you

are using.

Device data sheets and family reference manual sections are available for

download from the Microchip Worldwide Web site at: http://www.microchip.com

Section 14. High-Speed PWM

High-Speed PWM

14.3 CONTROL REGISTERS

The following registers control the operation of the High-Speed PWM module:

•PTCON: PWM Time Base Control Register

- Enables or disables the High-Speed PWM module

- Sets the Special Event Trigger for the ADC

- Enables or disables immediate period updates

- Selects the synchronizing source for the master time base

- Specifies synchronization settings

•PTCON2: PWM Clock Divider Select Register 2

Provides the clock prescaler to the PWM master time base

•PTPER: Primary Master Time Base Period Register

Provides the PWM time period value

•STCON: PWM Secondary Master Time Base Control Registe (1)

- Enables or disables immediate period updates based on the secondary master time base

- Selects the synchronization source for the secondary master time base

- Specifies the synchronization setting for secondary master time base control

• STCON2: PWM Secondary Clock Divider Select Register 2(1)

Provides the clock prescaler to the PWM secondary master time base

•STPER: Secondary Master Time Base Period Register(1)

Provides the secondary master time base period value

•MDC: PWM Master Duty Cycle Register

Provides the PWM master duty cycle value

•SEVTCMP: PWM Special Event Compare Register

Provides the compare value that is used to trigger the ADC module

•SSEVTCMP: PWM Secondary Special Event Compare Register(1)

Provides the compare value that is used to trigger the ADC module based on the

secondary master time base

•CHOP: PWM Chop Clock Generator Register

- Provides the chop clock frequency

- Enables or disables the chop clock generator

•PWMKEY: PWM Unlock Register(1)

Writes the unlock sequence to allow writes to the IOCONx and FCLCONx registers

•PWMCONx: PWM Control Register

- Enables or disables fault interrupt, current-limit interrupt and primary trigger interrupt

- Provides the interrupt status for fault interrupt, current-limit interrupt and primary trigger

interrupt

- Selects the type of time base (master time base or independent time base)

- Selects the type of duty cycle (master duty cycle or independent duty cycle)

- Controls Dead Time mode

- Enables or disables Center-Aligned mode

- Controls the external PWM Reset operation

- Enables or disables immediate updates of the duty cycle, phase offset, independent time

base period

•IOCONx: PWM I/O Control Register

- Enables or disables PWM pin control feature (PWM control or GPIO)

- Controls fault/current limit override values

- Enables PWMxH and PWMxL pin swapping

- Controls the PWMxH and PWMxL output polarity

- Controls the PWMxH and PWMxL output if any of the following modes is selected:

• Complementary mode

• Push-Pull mode

• True Independent mode

Note: Not all registers are available on all devices. Refer to the “High-Speed PWM”

chapter in the specific device data sheet for availability.

dsPIC33E/PIC24E Family Reference Manual

•FCLCONx: PWM Fault Current-Limit Control Register

- Selects the current-limit control signal source

- Selects the current-limit polarity

- Enables or disables Current-Limit mode

- Selects the fault control signal source

- Configures the fault polarity

- Enables or disables Fault mode

•PDCx: PWM Generator Duty Cycle Register(1)

- Provides the duty cycle value for the PWMxH and PWMxL outputs, if master time base is

selected

- Provides the duty cycle value for the PWMxH output, if independent time base is selected

•PHASEx: PWM Primary Phase Shift Register

- Provides the phase shift value for the PWMxH and PWMxL output, if master time base is

selected

- Provides the independent time base period for the PWMxH output, if independent time

base is selected

•SDCx: PWM Secondary Duty Cycle Register(1,2)

Provides the duty cycle value for the PWMxL output, if independent time base is selected

•SPHASEx: PWM Secondary Phase Shift Register(1,2,3)

- Provides the phase shift for the PWMxL output, if the master time base is selected

- Provides the independent time base period value for the PWMxL output, if the independent

time base is selected

•DTRx: PWM Dead Time Register

- Provides the dead time value for the PWMxH output, if positive dead time is selected

- Provides the dead time value for the PWMxL output, if negative dead time is selected

•ALTDTRx: PWM Alternate Dead Time Register

- Provides the dead time value for the PWMxL output, if positive dead time is selected

- Provides the dead time value for the PWMxH output, if negative dead time is selected

•TRIGx: PWM Primary Trigger Compare Value Register

Provides the compare value to generate the primary PWM trigger

•TRGCONx: PWM Trigger Control Register

- Enables the PWMx trigger postscaler start event

- Specifies the number of PWM cycles to skip before generating the first trigger

•LEBCONx: Leading-Edge Blanking Control Register

- Selects the rising or falling edge of the PWM output for LEB

- Enables or disables LEB for fault and current-limit inputs

•LEBDLYx: Leading-Edge Blanking Delay Register

Provides leading-edge blanking delay for the fault and current-limit inputs

•PWMCAPx: Primary PWM Time Base Capture Register

Provides the captured independent time base value when a leading edge is detected on

the current-limit input, and when LEB processing on the current-limit input signal is

completed

•AUXCONx: PWM Auxiliary Control Register

- Selects PWM state blank and chop clock sources

- Selects PWMxH and PWMxL output chopping functionality

dsPIC33E/PIC24E Family Reference Manual

U-0 U-0 U-0 U-0 U-0 U-0 U-0 U-0

— — — — — — — —

bit 15 bit 8

U-0 U-0 U-0 U-0 U-0 R/W-0 R/W-0 R/W-0

— — — — — PCLKDIV<2:0>(1)

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-3 Unimplemented: Read as ‘0’

bit 2-0 PCLKDIV<2:0>: PWM Input Clock Prescaler (Divider) Select bits(1)

111 = Reserved

110 = Divide by 64

101 = Divide by 32

100 = Divide by 16

011 = Divide by 8

010 = Divide by 4

001 = Divide by 2

000 = Divide by 1, maximum PWM timing resolution (power-on default)

Note 1: These bits should be changed only when PTEN = 0. Changing the clock selection during operation will

yield unpredictable results.

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

PTPER<15:8>(1)

bit 15 bit 8

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-0 R/W-0 R/W-0

PTPER<7:0>(1)

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-0 PTPER<15:0>: Primary Master Time Base (PMTMR) Period Value bits(1)

Note 1: 1 LSb = 1 Tosc. For example, 7.14 ns for 70 MIPS operation.

Section 14. High-Speed PWM

High-Speed PWM

U-0 U-0 U-0 HS/HC-0 R/W-0 R/W-0 R/W-0 R/W-0

— — — SESTAT SEIEN EIPU(2) SYNCPOL SYNCOEN

bit 15 bit 8

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SYNCEN SYNCSRC<2:0> SEVTPS<3:0>

bit 7 bit 0

Legend: HC = Cleared in Hardware HS = Set in Hardware

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-13 Unimplemented: Read as ‘0’

bit 12 SESTAT: Special Event Interrupt Status bit

1 = Secondary Special Event Interrupt is pending

0 = Secondary Special Event Interrupt is not pending

bit 11 SEIEN: Special Event Interrupt Enable bit

1 = Secondary Special Event Interrupt is enabled

0 = Secondary Special Event Interrupt is disabled

bit 10 EIPU: Enable Immediate Period Updates bit(2)

1 = Active Secondary Period register is updated immediately

0 = Active Secondary Period register updates occur on PWM cycle boundaries

bit 9 SYNCPOL: Synchronize Input and Output Polarity bit

1 = SYNCO2 output is active-low

0 = SYNCO2 output is active-high

bit 8 SYNCOEN: Secondary Master Time Base Sync Enable bit

1 = SYNCO2 output is enabled

0 = SYNCO2 output is disabled

bit 7 SYNCEN: External Secondary Master Time Base Synchronization Enable bit

1 = External synchronization of secondary time base is enabled

0 = External synchronization of secondary time base is disabled

bit 6-4 SYNCSRC<2:0>: Secondary Time Base Sync Source Selection bits

These bits select the SYNCIx or PTGOx input as the synchronous source. Refer to the “High-Speed

PWM” chapter in the specific device data sheet for availability.

bit 3-0 SEVTPS<3:0>: PWM Secondary Special Event Trigger Output Postscaler Select bits

1111 = 1:16 Postscale

•

0001 = 1:2 Postscale

0000 = 1:1 Postscale

Note 1: This register is not available on all devices. Refer to the “High-Speed PWM” chapter of the specific

device data sheet for availability.

2: This bit only applies to the secondary master time base period.

dsPIC33E/PIC24E Family Reference Manual

(1)

U-0 U-0 U-0 U-0 U-0 U-0 U-0 U-0

— — — — — — — —

bit 15 bit 8

U-0 U-0 U-0 U-0 U-0 R/W-0 R/W-0 R/W-0

— — — — — PCLKDIV<2:0>(2)

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-3 Unimplemented: Read as ‘0’

bit 2-0 PCLKDIV<2:0>: PWM Input Clock Prescaler (Divider) Select bits(2)

111 = Reserved

110 = Divide by 64

101 = Divide by 32

100 = Divide by 16

011 = Divide by 8

010 = Divide by 4

001 = Divide by 2

000 = Divide by 1, maximum PWM timing resolution (power-on default)

Note 1: This register is not available on all devices. Refer to the “High-Speed PWM” chapter of the specific

device data sheet for availability.

2: These bits should be changed only when PTEN = 0. Changing the clock selection during operation will

yield unpredictable results.

Section 14. High-Speed PWM

High-Speed PWM

(1)

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

STPER<15:8>

bit 15 bit 8

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

STPER<7:0>

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-0 STPER<15:0>: Secondary Master Time Base Period Value bits

Note 1: This register is not available on all devices. Refer to the “High-Speed PWM” chapter of the specific

device data sheet for availability.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

MDC<15:8>

bit 15 bit 8

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

MDC<7:0>

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-0 MDC<15:0>: Master PWM Duty Cycle Value bits

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SEVTCMP<15:8>

bit 15 bit 8

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SEVTCMP<7:0>

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-0 SEVTCMP<15:0>: Special Event Compare Count Value bits

dsPIC33E/PIC24E Family Reference Manual

(1)

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SSEVTCMP<15:8>

bit 15 bit 8

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SSEVTCMP<7:0>

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-0 SSEVTCMP<15:0>: Secondary Special Event Compare Count Value bits

The optional SSEVTCMP register and the optional secondary master time base provide an additional

Special Event Trigger. The secondary special event trigger also has its own postscaler controlled by

the SEVTPS<3:0> bits in the STCON register.

Note 1: This register is not available on all devices. Refer to the “High-Speed PWM” chapter of the specific

device data sheet for availability.

R/W-0 U-0 U-0 U-0 U-0 U-0 R/W-0 R/W-0

CHPCLKEN — — — — — CHOPCLK<9:8>

bit 15 bit 8

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

CHOPCLK<7:0>

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15 CHPCLKEN: Enable Chop Clock Generator bit

1 = Chop clock generator is enabled

0 = Chop clock generator is disabled

bit 14-10 Unimplemented: Read as ‘0’

bit 9-0 CHOPCLK<9:0>: Chop Clock Divider bits

Chop Frequency = (FP/PLKDIV) / (CHOPCLK<9:0> + 1)

As an example, for devices running at 60 MIPS, a value of all zeros will yield a 60 MHz chop clock

(period = 16.7 ns) with the PWM clock prescaler configured for fastest clock. A value of ‘0000000001’

in the CHOPCLK<9:0> bits will yield a 30 MHz chop clock with the PWM clock prescaler configured

for fastest clock.

Note: The chop clock generator operates with the Primary PWM Clock Prescaler bits (PCLKDIV<2:0>) in the

PTCON2 register.

dsPIC33E/PIC24E Family Reference Manual

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

PENH PENL POLH POLL PMOD<1:0> OVRENH OVRENL

bit 15 bit 8

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

OVRDAT<1:0> FLTDAT<1:0>(1,2) CLDAT<1:0> SWAP OSYNC

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15 PENH: PWMxH Output Pin Ownership bit

1 = PWM module controls PWMxH pin

0 = GPIO module controls PWMxH pin

bit 14 PENL: PWMxL Output Pin Ownership bit

1 = PWM module controls PWMxL pin

0 = GPIO module controls PWMxL pin

bit 13 POLH: PWMxH Output Pin Polarity bit

1 = PWMxH pin is active-low

0 = PWMxH pin is active-high

bit 12 POLL: PWMxL Output Pin Polarity bit

1 = PWMxL pin is active-low

0 = PWMxL pin is active-high

bit 11-10 PMOD<1:0>: PWM # I/O Pin Mode bits

11 = PWM I/O pin pair is in True Independent PWM Output mode

(3)

10 = PWM I/O pin pair is in Push-Pull Output mode

01 = PWM I/O pin pair is in Redundant Output mode

00 = PWM I/O pin pair is in Complementary Output mode

bit 9 OVRENH: Override Enable for PWMxH Pin bit

1 = OVRDAT<1> provides data for output on PWMxH pin

0 = PWM generator provides data for PWMxH pin

bit 8 OVRENL: Override Enable for PWMxL Pin bit

1 = OVRDAT<0> provides data for output on PWMxL pin

0 = PWM generator provides data for PWMxL pin

bit 7-6 OVRDAT<1:0>: State(2) for PWMxH, PWMxL Pins if Override is Enabled bits

If OVERENH = 1, OVRDAT<1> provides data for PWMxH

If OVERENL = 1, OVRDAT<0> provides data for PWMxL

Note 1: These bits must not be changed after the PWM module is enabled (PTEN = 1).

2: State represents Active/Inactive state of the PWM, depending on the POLH and POLL bits. For example, if

FLTDAT<1> is set to ‘1’ and POLH is set to ‘1’, the PWMxH pin will be at logic level 0 (active level) when a

fault occurs.

3: This feature is not available on all devices. Refer to the “High-Speed PWM” chapter of the specific device

data sheet for availability.

Section 14. High-Speed PWM

High-Speed PWM

bit 5-4 FLTDAT<1:0>: State(2) for PWMxH and PWMxL Pins if FLTMOD is Enabled bits(1)

IFLTMOD (FCLCONx<15>) = 0: Normal Fault mode:

If fault is active, FLTDAT<1> provides the state for PWMxH.

If fault is active, FLTDAT<0> provides the state for PWMxL.

IFLTMOD (FCLCONx<15>) = 1: Independent Fault mode:

If current-limit is active, FLTDAT<1> provides the state for PWMxH.

If fault is active, FLTDAT<0> provides the state for PWMxL.

bit 3-2 CLDAT<1:0>: State(2) for PWMxH and PWMxL Pins if CLMOD is Enabled bits

IFLTMOD (FCLCONx<15>) = 0: Normal Fault mode:

If current-limit is active, CLDAT<1> provides the state for PWMxH.

If current-limit is active, CLDAT<0> provides the state for PWMxL.

IFLTMOD (FCLCONx<15>) = 1: Independent Fault mode:

The CLDAT<1:0> bits are ignored.

bit 1 SWAP: SWAP PWMxH and PWMxL Pins bit

1 = PWMxH output signal is connected to PWMxL pin; PWMxL output signal is connected to PWMxH

0 = PWMxH and PWMxL output signals pins are mapped to their respective pins

bit 0 OSYNC: Output Override Synchronization bit

1 = Output overrides via the OVRDAT<1:0> bits are synchronized to the PWM time base

0 = Output overrides via the OVRDAT<1:0> bits occur on next CPU clock boundary

Note 1: These bits must not be changed after the PWM module is enabled (PTEN = 1).

2: State represents Active/Inactive state of the PWM, depending on the POLH and POLL bits. For example, if

FLTDAT<1> is set to ‘1’ and POLH is set to ‘1’, the PWMxH pin will be at logic level 0 (active level) when a

fault occurs.

3: This feature is not available on all devices. Refer to the “High-Speed PWM” chapter of the specific device

data sheet for availability.

Section 14. High-Speed PWM

High-Speed PWM

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

PDCx<15:8>

bit 15 bit 8

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

PDCx<7:0>

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-0 PDCx<15:0>: PWM Generator # Duty Cycle Value bits

Note 1: In Independent PWM mode, PMOD<1:0> (IOCONx<11:10>) = 11, the PDCx register controls the PWMxH

duty cycle only. In Complementary, Redundant and Push-Pull PWM modes (PMOD<1:0>

(IOCONx<11:0>) = 00 01, , or 10), the PDCx register controls the duty cycle of both the PWMxH and

PWMxL.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

PHASEx<15:8>

bit 15 bit 8

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

PHASEx<7:0>

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-0 PHASEx<15:0>: PWM Phase Shift Value or Independent Time Base Period bits for the PWM Generator

Note 1: If the ITB bit = 0 (PWMCONx<9>), the following applies based on the mode of operation:

• Complementary, Redundant and Push-Pull Output mode (PMOD<1:0> (IOCONx<11:10>) = 00,

01 10, or ) PHASEx<15:0> = Phase shift value for PWMxH and PWMxL outputs

• True Independent Output mode (PMOD<1:0> (IOCONx<11:10>) = 11) PHASEx<15:0> = Phase

shift value for PWMxH only

2: If the ITB bit = 1(PWMCONx<9>), the following applies based on the mode of operation:

• Complementary, Redundant, and Push-Pull Output mode (PMOD<1:0> (IOCONx<11:10>) = 00,

01 10, or ) PHASEx<15:0> = Independent time base period value for PWMxH and PWMxL

• True Independent Output mode (PMOD<1:0> (IOCONx<11:10>) = 11) PHASEx<15:0> = Independent

time base period for PWMxH only

dsPIC33E/PIC24E Family Reference Manual

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SDCx<15:8>

bit 15 bit 8

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SDCx<7:0>

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-0 SDCx<15:0>: Secondary Duty Cycle bits for PWMxL output pin

Note 1: The SDCx register is used in Independent PWM mode only (PMOD<1:0> (IOCONx<11:10>) = 11. When

used in Independent PWM mode, the SDCx register controls the PWMxL duty cycle.

2: This register is not available on all devices. Refer to the “High-Speed PWM” chapter of the specific

device data sheet for availability.

(1,2,3)

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SPHASEx<15:8>

bit 15 bit 8

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SPHASEx<7:0>

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-0 SPHASEx<15:0>: Secondary Phase Offset bits for PWMxL Output Pin

Note 1: If the ITB bit = 0 (PWMCONx<9>), the following applies based on the mode of operation:

• Complementary, Redundant and Push-Pull Output mode (PMOD<1:0> (IOCONx<11:10>) = 00,

01 10, or ) SPHASEx<15:0> = Not used

• True Independent Output mode (PMOD<1:0> (IOCONx<11:10>) = 11) SPHASEx<15:0> = Phase

shift value for PWMxL only

2: If the ITB bit = 1 (PWMCONx<9>), the following applies based on the mode of operation:

• Complementary, Redundant and Push-Pull Output mode (PMOD<1:0> (IOCONx<11:10>) = 00,

01 10, or ) SPHASEx<15:0> = Not used

• True Independent Output mode (PMOD<1:0> (IOCONx<11:10>) = 11) SPHASEx<15:0> =

Independent time base period value for PWMxL only

3: This register is not available on all devices. Refer to the “High-Speed PWM” chapter of the specific device

data sheet for availability.

dsPIC33E/PIC24E Family Reference Manual

R/W-0 R/W-0 R/W-0 R/W-0 U-0 U-0 U-0 U-0

TRGDIV<3:0> — — — —

bit 15 bit 8

U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

— — TRGSTRT<5:0>

bit 7 bit 0

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 15-12 TRGDIV<3:0>: Trigger # Output Divider bits

1111 = Trigger output for every 16th trigger event

•

0010 = Trigger output for every 3rd trigger event

0001 = Trigger output for every 2nd trigger event

0000 = Trigger output for every trigger event

bit 11-6 Unimplemented: Read as ‘0’

bit 5-0 TRGSTRT<5:0>: Trigger Postscaler Start Enable Select bits

111111 = Wait 63 PWM cycles before generating the first trigger event after the module is enabled

•

000010 = Wait 2 PWM cycles before generating the first trigger event after the module is enabled

000001 = Wait 1 PWM cycles before generating the first trigger event after the module is enabled

000000 = Wait 0 PWM cycles before generating the first trigger event after the module is enabled

Section 14. High-Speed PWM

High-Speed PWM

The High-Speed PWM module contains multiple PWM generators. Each PWM generator

provides two PWM outputs: PWMxH and PWMxL. A master time base generator provides a

synchronous signal as a common time base to synchronize the various PWM outputs. Each

generator can operate independently or in sync with the master time base.

The individual PWM

outputs are available on the output pins of the device. The input fault signals and current-limit

signals, when enabled, monitor and protect the system by placing the PWM outputs into a known

“safe” state.

Each PWM generator can create a trigger to the ADC module to sample the analog signal at a

specific instance during the PWM period. In addition, the High-Speed PWM module also

generates a Special Event Trigger to the ADC module based on the master time base.

The High-Speed PWM module can synchronize itself with an external signal or can act as a

synchronizing source to any external device. The SYNCIx is the input pin, which can synchronize

the High-Speed PWM module with an external signal. The SYNCOx pin is an output pin that

provides a synchronous signal to an external device.

The High-Speed PWM module can be used for a wide variety of power conversion/motor control

applications that require:

• High operating frequencies with good resolution

• Ability to dynamically control PWM parameters such as duty cycle, period and dead time

• Ability to independently control each PWM

• Ability to synchronously control all PWMs

• Independent resource allocation for each PWM generator

• Fault handling capability

• CPU load staggering to execute multiple control loops

Each function of the High-Speed PWM module is described in detail in subsequent sections.

Figure 14-2 illustrates the interconnections between various registers in the High-Speed PWM

module.

dsPIC33E/PIC24E Family Reference Manual

Figure 14-2: High-Speed PWM Module Register Interconnection Diagram

MUX

PTMRx

PDCx

PWMCONx TRGCONx

PTCON, PTCON2

IOCONx

DTRx

PWMxL

PWMxH

FLTx

PWM1L

PWM1H

FCLCONx

MDC

PHASEx

LEBCONx

MUX

STMRx

SDCx

SPHASEx ALTDTRx

PWMCAPx

User Override Logic

Current-Limit

PWM Output Mode

Control Logic

Dead

Logic

Control

Logic

Fault and

Current-Limit

Logic

PWM Generator 1

FLTx

PWM Generator x

Interrupt

Logic

ADC Trigger

Module Control and Timing

Master Duty Cycle Register

Synchronization Synchronization

Master PeriodMaster Period

Master Duty CycleMaster Duty Cycle

Secondary PWM

SYNCI2

SYNCI1

SYNCO1

SEVTCMP

Comparator Special Event Trigger

Special Event

Postscaler

PTPER

PMTMR Primary Master Time Base

Master Time Base Counter

Special Event Compare Trigger

Comparator

Clock

Prescaler

Comparator

16-bit Data Bus

Time

TRIGx Fault Override Logic

Override Logic

SYNCO2

SEVTCMP

Comparator Special Event Trigger

Special Event

Postscaler

PTPER

PMTMR Secondary Master Time Base

Master Time Base Counter

Special Event Compare Trigger

Comparator

Clock

Prescaler

DTCMPx

DTCMP1

Note 1: Not all of the features and registers listed in this block diagram are available on all devices. Refer to the

“High-Speed PWM” chapter of the specific device data sheet for availability.

dsPIC33E/PIC24E Family Reference Manual

14.5.4 Standard Edge-Aligned PWM

The standard edge-aligned PWM waveforms are illustrated in Figure 14-3. To create the

edge-aligned PWM, a timer or counter circuit counts upward from zero to a specified maximum

value, called Period. Another register contains the duty cycle value, which is constantly

compared with the timer value. When the timer or counter value is less than or equal to the duty

cycle value, the PWM output signal is asserted. When the timer value exceeds the duty cycle

value, the PWM signal is deasserted. When the timer value is greater than or equal to the period

value, the timer resets itself and the process repeats.

Figure 14-3: Standard Edge-Aligned PWM Mode

14.5.5 Center-Aligned PWM

The center-aligned PWM waveforms illustrated in Figure 14-4, align the PWM signals with

respect to a reference point so that half of the PWM signal occurs before the reference point and

the remaining half of the signal occurs after the reference point. The Center-Aligned mode is

enabled when the CAM bit (PWMCONx<2>) is set.

When operating in Center-Aligned mode, the effective PWM period is twice the value specified

in the PHASEx registers, because the independent time base counter in the PWM generator is

counting up and then counting down during the cycle. The up/down count sequence doubles the

effective PWM cycle period. This mode is used in many motor control applications.

Note: The Independent Time Base mode (ITB = 1) must be enabled to use the

Center-Aligned mode. If ITB = 0, the CAM bit is ignored.

PDC1

Period

Value

Timer

Value

Duty Cycle Match Timer Resets

Period

Duty Cycle

Period

TOFFTON

PWMxH

Section 14. High-Speed PWM

High-Speed PWM

Figure 14-4: Center-Aligned PWM Mode

Example 14-2: Edge-Aligned or Center-Aligned Mode Selection

PWM1H

PWM2H

PDC1

PDC2

PHASEx

Period

2 x Period

/* Select Edge-Aligned PWM Time Base */

PWMCON1bits.CAM = 0; /* For Edge-Aligned mode */

/* Select Center-Aligned PWM Time Base */

PWMCON1bits.CAM = 1; /* For Center-Aligned mode */

PWMCON1bits.ITB = 1; /* Must be set for Center-Aligned mode */

Section 14. High-Speed PWM

High-Speed PWM

An external device can also be synchronized with the master time base using the

Synchronization Output (SYNCOx) signal. The SYNCOx signal is generated when the PTPER

devices reliably sense the signals. The polarity of the SYNCOx signal is determined by the

SYNCPOL bit (PTCON<9>). The SYNCOx signal can be enabled or disabled by selecting the

SYNCOEN bit (PTCON<8>).

The advantage of synchronization is that it ensures the beat frequencies are not generated when

multiple power controllers are in use.

Example 14-3: Synchronizing Master Time Base with External Signal

Example 14-4: Synchronizing External Device with Master Time Base

14.5.8 Special Event Trigger

The High-Speed PWM module has a master Special Event Trigger that can be used for

synchronization of analog-to-digital conversions with the PWM time base. The analog-to-digital

sampling and conversion time can be programmed to occur within the PWM period. The Special

Event Trigger allows the user-assigned application to minimize the delay between the time the

conversion results are acquired and the time the duty cycle value is updated. The Special Event

Trigger is based on the master time base.

The master Special Event Trigger value is loaded into the PWM Special Event Compare register

(SEVTCMP). In addition, the SEVTPS<3:0> bits (PTCON<3:0>), control the Special Event

Trigger operation. To generate a trigger to the ADC module, the value in the PTPER register is

compared with the value in the SEVTCMP register. The master Special Event Trigger has a

postscaler that allows a 1:1 to 1:16 postscaler ratio. The postscaler is configured by writing to the

SEVTPS<3:0> bits (PTCON<3:0>).

The Special Event Trigger pulses are always generated during the following instances:

• On a match condition regardless of the status of the Special Event Interrupt Enable bit

(SEIEN)

• If the compare value in the SEVTCMP register is a value from zero to a maximum value of

the PTPER register

Note 1: The SYNCIx pulse should be greater than the PWM period value.

2: The SYNCIx pulse should be continuous with a minimum pulse-width of 200 ns.

3: The PWM cycles are expected to be distorted for the first two SYNCIx pulses.

4: The period value should be a multiple of 8 (Least Significant 3 bits set to ‘0’) for the

external synchronization to work in the Push-Pull mode.

5: There is a delay from the input of a SYNC signal until the internal time base counter

is Reset. This will be approximately 2.5 * prescale clock period.

6: The External Time Base Synchronization must not be used with phase shifted PWM

as the synchronization signal may not maintain the phase relationships between the

multiple PWM channels.

7: The External Time Base Synchronization cannot be used in Independent Time

Base mode.

/* Synchronizing Master Time Base with External Signal */

PTCONbits.SYNCSRC = 0; /* Select SYNC1 input as synchronizing source */

PTCONbits.SYNCPOL = 0; /* Rising edge of SYNC1 resets the PWM Timer */

PTCONbits.SYNCEN = 1; /* Enable external synchronization */

/* Synchronizing External Device with Master Time Base */

PTCONbits.SYNCPOL = 0; /* SYNCO output is active-high */

PTCONbits.SYNCOEN = 1; /* Enable SYNCO output */

Section 14. High-Speed PWM

High-Speed PWM

14.6 PWM OPERATING MODES

The High-Speed PWM module supports the following operation modes:

• Push-Pull Output mode

• Complementary Output mode

• Redundant Output mode

• Independent Output mode (this feature is not available on all devices)

These operating modes can be selected using the PMOD<1:0> bits (IOCONx<11:10>).

In the following sections, figures and examples are provided, which show the PWM outputs in

multiple operating modes. Table 14-1 provides a list of the available modes and settings, with

references to the figures by number.

Table 14-1: Mode and Code Cross-reference Table

PWM Mode Mode Settings Related

Figure

Push-Pull Independent Duty Cycle and Phase, Fixed Primary Period, Edge-Aligned 14-7

Independent Duty Cycle and Phase, Fixed Secondary Period, Edge-Aligned 14-8

Master Duty Cycle and Independent Phase, Fixed Primary Period, Edge-Aligned 14-9

Master Duty Cycle and Independent Phase, Fixed Secondary Period, Edge-Aligned 14-10

Independent Duty Cycles and Periods, No Phase-Shifting, Edge-Aligned 14-11

Master Duty Cycles and Independent Periods, No Phase-Shifting, Edge-Aligned 14-12

Independent Duty Cycles and Periods, No Phase-Shifting, Center-Aligned Mode 14-13

Master Duty Cycles and Independent Periods, No Phase-Shifting, Center-Aligned Mode 14-14

Complementary Independent Duty Cycle and Phase, Fixed Primary Period, Edge-Aligned 14-15

Independent Duty Cycle and Phase, Fixed Secondary Period, Edge-Aligned 14-16

Master Duty Cycle and Independent Phase, Fixed Primary Period, Edge-Aligned 14-17

Master Duty Cycle and Independent Phase, Fixed Secondary Period, Edge-Aligned 14-18

Independent Duty Cycles and Periods, No Phase-Shifting, Edge-Aligned 14-19

Master Duty Cycles and Independent Periods, No Phase-Shifting, Edge-Aligned 14-20

Independent Duty Cycles and Periods, No Phase-Shifting, Center-Aligned 14-21

Master Duty Cycles and Independent Periods, No Phase-Shifting, Center-Aligned 14-22

Redundant Independent Duty Cycle and Phase, Fixed Primary Period, Edge-Aligned 14-23

Independent Duty Cycle and Phase, Fixed Secondary Period, Edge-Aligned 14-24

Master Duty Cycle and Variable Phase, Fixed Primary Period, Edge-Aligned 14-25

Master Duty Cycle and Variable Phase, Fixed Secondary Period, Edge-Aligned 14-26

Independent Duty Cycles and Periods, No Phase-Shifting, Edge-Aligned 14-27

Master Duty Cycles and Independent Periods, No Phase-Shifting, Edge-Aligned 14-28

Independent Duty Cycles and Periods, No Phase-Shifting, Center-Aligned 14-29

Master Duty Cycles and Independent Periods, No Phase-Shifting, Center-Aligned 14-30

Independent Independent Duty Cycle and Phase, Fixed Primary Period, Edge-Aligned 14-31

Independent Duty Cycle and Phase, Fixed Secondary Period, Edge-Aligned 14-32

Master Duty Cycle, Variable Phase, Fixed Primary Period, Edge-Aligned 14-33

Master Duty Cycle, Variable Phase, Fixed Secondary Period, Edge-Aligned 14-34

Independent Duty Cycles and Periods, No Phase-Shifting, Edge-Aligned 14-35

Master Duty Cycles, Independent Periods, No Phase-Shifting, Edge-Aligned 14-36

Independent Duty Cycles and Periods, No Phase-Shifting, Center-Aligned 14-37

Master Duty Cycles, Independent Periods, No Phase-Shifting, Center-Aligned 14-38

dsPIC33E/PIC24E Family Reference Manual

14.6.1 Push-Pull PWM Mode

In Push-Pull mode, the PWM outputs are alternately available on the PWMxH and PWMxL pins.

Some typical applications of Push-Pull mode are provided in 14.16 “Application Information”.

Figure 14-7 through Figure 14-14 and Example 14-6 through Example 14-13 show the PWM

outputs for Push-Pull PWM mode in multiple operating modes.

Figure 14-7: Push-Pull PWM Mode – Independent Duty Cycle and Phase, Fixed Primary Period,

Edge-Aligned

Note: Not all of the features and registers listed in the Figures and Code Examples in this

section are available on all devices. Refer to the “High-Speed PWM” chapter of the

specific device data sheet for availability.

PTPER

PHASE1 = 0

PHASE2

PHASE3

PDC1

Where:

PHASEx Phase of PWMxH and PWMxL

PDCx Duty Cycle of PWMxH and PWMxL

PTPER Period of PWMxH and PWMxL

DTRx Dead Time for PWMxH Rising Edge

ALTDTRx Dead Time for PWMxL Rising Edge

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

Start of

PWM Cycle

PDC1

PDC2

PDC3

Complete

PWM1L Cycle

DTR1

ALTDTR1

ALTDTR2

DTR2

ALTDTR3

DTR3

Section 14. High-Speed PWM

High-Speed PWM

Example 14-8: Push-Pull PWM Mode – Master Duty Cycle and Independent Phase, Fixed Primary Period,

Edge-Aligned

Figure 14-10: Push-Pull PWM Mode – Master Duty Cycle and Independent Phase, Fixed Secondary Period,

Edge-Aligned

/* Set PWM Period on Primary Time Base*/

PTPER = 1000;

/* Set Phase Shift */

PHASE1 = 0;

PHASE2 = 100;

PHASE3 = 200;

/* Set Duty Cycles */

MDC = 200;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 25;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 25;

/* Set PWM Mode to Push-Pull */

IOCON1 = IOCON2 = IOCON3 = 0xC800;

/* Set Primary Time Base, Edge-Aligned Mode and Master Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0100;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

Where:

PHASEx Phase of PWMxH and PWMxL

MDC Duty Cycle of PWMxH and PWMxL

STPER Period of PWMxH and PWMxL

DTRx Dead Time for PWMxH Rising Edge

ALTDTRx Dead Time for PWMxL Rising Edge

STPER

PHASE1 = 0

PHASE2

PHASE3

MDC

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

Start of

PWM Cycle

MDC

Complete

PWM1L Cycle

DTR1

ALTDTR1

ALTDTR2

DTR2

ALTDTR3

DTR3

dsPIC33E/PIC24E Family Reference Manual

Example 14-9: Push-Pull PWM Mode – Master Duty Cycle and Independent Phase, Fixed Secondary Period,

Edge-Aligned

Figure 14-11: Push-Pull PWM Mode – Independent Duty Cycles and Independent Periods, No Phase-Shifting,

Edge-Aligned

/* Set PWM Period on Secondary Time Base*/

STPER = 1000;

/* Set Phase Shift */

PHASE1 = 0;

PHASE2 = 100;

PHASE3 = 200;

/* Set Duty Cycles */

MDC = 200;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 25;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 25;

/* Set PWM Mode to Push-Pull */

IOCON1 = IOCON2 = IOCON3 = 0xC800;

/* Set Secondary Time Base, Edge-Aligned Mode and Master Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0108;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

PDC1

PDC2

PDC3

PHASE1

PHASE2

PHASE3

Start of

PWM Cycle Complete

PWM1L Cycle

Where:

PHASEx Period of PWMxH and PWMxL

PDCx Duty Cycle of PWMxH and PWMxL

DTRx Dead time for PWMxH Rising Edge

ALTDTRx Dead time for PWMxL Rising Edge

ALTDTR3

ALTDTR2

ALTDTR1 DTR1

DTR2

DTR3

Section 14. High-Speed PWM

High-Speed PWM

Example 14-10: Push-Pull PWM Mode – Independent Duty Cycles and Independent Periods, No

Phase-Shifting, Edge-Aligned

Figure 14-12: Push-Pull PWM Mode – Master Duty Cycles and Independent Periods, No Phase-Shifting,

Edge-Aligned

/* Set PWM Periods on PHASEx Registers */

PHASE1 = 1000;

PHASE2 = 900;

PHASE3 = 800;

/* Set Duty Cycles */

PDC1 = 200;

PDC2 = 300;

PDC3 = 400;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 25;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 25;

/* Set PWM Mode to Push-Pull */

IOCON1 = IOCON2 = IOCON3 = 0xC800;

/* Set Independent Time Bases, Edge-Aligned Mode and Independent Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0200;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

MDC

PHASE1

PHASE2

PHASE3

Start of

PWM Cycle Complete

PWM1L Cycle

Where:

PHASEx Period of PWMxH and PWMxL

MDC Duty Cycle of PWMxH and PWMxL

DTRx Dead Time for PWMxH Rising Edge

ALTDTRx Dead Time for PWMxL Rising Edge

ALTDTR3

ALTDTR2

ALTDTR1 DTR1

DTR2

DTR3

dsPIC33E/PIC24E Family Reference Manual

Example 14-11: Push-Pull PWM Mode – Master Duty Cycles and Independent Periods, No Phase-Shifting,

Edge-Aligned

Figure 14-13: Push-Pull PWM Mode – Independent Duty Cycles and Independent Periods, No Phase-Shifting,

Center-Aligned Mode

/* Set PWM Periods on PHASEx Registers */

PHASE1 = 1000;

PHASE2 = 900;

PHASE3 = 800;

/* Set Duty Cycles */

MDC = 200;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 25;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 25;

/* Set PWM Mode to Push-Pull */

IOCON1 = IOCON2 = IOCON3 = 0xC800;

/* Set Independent Time Bases, Edge-Aligned Mode and Master Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0300;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

Start of

PWM Cycle

PHASE1

PHASE2

PHASE3

PDC1

PDC2

PDC3

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

Complete PWM1L

and PWM1H Cycle

Where:

PHASEx Period of PWMxH and PWMxL

PDCx Duty Cycle of PWMxH and PWMxL

DTRx Dead Time before PWMxH Falling Edge

ALTDTRx Dead Time before PWMxL Falling Edge

DTR1

ALTDTR1

DTR2

ALTDTR2

DTR3

ALTDTR3

PDC1

Section 14. High-Speed PWM

High-Speed PWM

14.6.2 Complementary PWM Mode

In Complementary PWM mode, the PWM output PWMxH is the complement of the PWMxL

output. Some typical applications of Complementary PWM mode are provided in

14.16 “Application Information”.

Figure 14-15 through Figure 14-22 and Example 14-14 through Example 14-21 show the PWM

outputs in multiple operating modes when the module operates in Complementary PWM mode.

Figure 14-15: Complementary PWM Mode – Independent Duty Cycle and Phase, Fixed Primary Period,

Edge-Aligned

Note: Not all of the features and registers listed in the Figures and Code Examples in this

section are available on all devices. Refer to the “High-Speed PWM” chapter of the

specific device data sheet for availability.

PTPER

PHASE1 = 0

PHASE2

PHASE3

PDC1

PDC2

PDC3

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

Start of PWM Cycle

Where: PHASEx Phase of PWMxH and PWMxL

PDCx Duty Cycle of PWMxH and PWMxL

PTPER Period of PWMxH and PWMxL

DTRx Dead Time for PWMxH Rising Edge

ALTDTRx Dead Time for PWMxL Rising Edge

DTR1

DTR2

DTR3

ALTDTR1

ALTDTR2

ALTDTR3

Section 14. High-Speed PWM

High-Speed PWM

Example 14-15: Complementary PWM Mode – Independent Duty Cycle and Phase, Fixed Secondary Period,

Edge-Aligned

Figure 14-17: Complementary PWM Mode – Master Duty Cycle and Independent Phase, Fixed Primary

Period, Edge-Aligned

/* Set PWM Period on Secondary Time Base */

STPER = 1000;

/* Set Phase Shift */

PHASE1 = 0;

PHASE2 = 100;

PHASE3 = 200;

/* Set Duty Cycles */

PDC1 = 150;

PDC2 = 200;

PDC3 = 400;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 25;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 25;

/* Set PWM Mode to Complementary */

IOCON1 = IOCON2 = IOCON3 = 0xC000;

/* Set Secondary Time Base, Edge-Aligned Mode and Independent Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0008;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

PTPER

PHASE1 = 0

PHASE2

PHASE3

MDC

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

MDC

Start of

PWM Cycle

Where:

PHASEx Phase of PWMxH and PWMxL

PDCx Duty Cycle of PWMxH and PWMxL

PTPER Period of PWMxH and PWMxL

DTRx Dead Time for PWMxH Rising Edge

ALTDTRx Dead Time for PWMxL Rising Edge

DTR1

DTR2

DTR3

ALTDTR1

ALTDTR2

ALTDTR3

Section 14. High-Speed PWM

High-Speed PWM

Example 14-17: Complementary PWM Mode – Master Duty Cycle and Independent Phase, Fixed Secondary

Period, Edge-Aligned

Figure 14-19: Complementary PWM Mode – Independent Duty Cycles and Independent Periods, No

Phase-Shifting, Edge-Aligned

/* Set PWM Period on Secondary Time Base*/

STPER = 1000;

/* Set Phase Shift */

PHASE1 = 0;

PHASE2 = 100;

PHASE3 = 200;

/* Set Duty Cycles */

MDC = 200;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 25;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 25;

/* Set PWM Mode to Complementary */

IOCON1 = IOCON2 = IOCON3 = 0xC000;

/* Set Secondary Time Base, Edge-Aligned Mode and Master Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0108;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

PDC1

PDC2

PDC3

PHASE1

PHASE2

PHASE3

Start of

PWM Cycle

DTR1

DTR2

DTR3

ALTDTR1

ALTDTR2

ALTDTR3

Where:

PHASEx Period of PWMxH and PWMxL

PDCx Duty Cycle of PWMxH and PWMxL

DTRx Dead Time for PWMxH Rising Edge

ALTDTRx Dead Time for PWMxL Rising Edge

dsPIC33E/PIC24E Family Reference Manual

Example 14-18: Complementary PWM Mode – Independent Duty Cycles and Independent Periods, No

Phase-Shifting, Edge-Aligned

Figure 14-20: Complementary PWM Mode – Master Duty Cycles and Independent Periods, No Phase-Shifting,

Edge-Aligned

/* Set PWM Periods on PHASEx Registers */

PHASE1 = 800;

PHASE2 = 900;

PHASE3 = 1000;

/* Set Duty Cycles */

PDC1 = 200;

PDC2 = 300;

PDC3 = 400;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 25;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 25;

/* Set PWM Mode to Complementary */

IOCON1 = IOCON2 = IOCON3 = 0xC000;

/* Set Independent Time Bases, Edge-Aligned Mode and Independent Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0200;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

MDC

PHASE1

PHASE2

PHASE3

Start of

PWM Cycle

DTR1

DTR2

DTR3

ALTDTR1

ALTDTR2

ALTDTR3

Where:

PHASEx Period of PWMxH and PWMxL

MDC Duty Cycle of PWMxH and PWMxL

DTRx Dead Time for PWMxH Rising Edge

ALTDTRx Dead Time for PWMxL Rising Edge

dsPIC33E/PIC24E Family Reference Manual

Example 14-27: Redundant PWM Mode – Master Duty Cycles and Independent Periods, No Phase-Shifting,

Edge-Aligned

Figure 14-29: Redundant PWM Mode – Independent Duty Cycles and Independent Periods, No

Phase-Shifting, Center-Aligned

/* Set PWM Periods on PHASEx Registers */

PHASE1 = 800;

PHASE2 = 900;

PHASE3 = 1000;

/* Set Duty Cycles */

MDC = 200;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 0;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 0;

/* Set PWM Mode to Redundant */

IOCON1 = IOCON2 = IOCON3 = 0xC400;

/* Set Independent Time Bases, Edge-Aligned Mode and Master Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0300;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

PDC1

PDC2

PDC3

PHASE1

PHASE2

PHASE3

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

Start of

PWM Cycle

Complete

PWM1H and

PWM1L Cycle

Where:

PHASEx Period of PWMxH and PWMxL

PDCx Duty Cycle of PWMxH and PWMxL

Section 14. High-Speed PWM

High-Speed PWM

Example 14-28: Redundant PWM Mode – Independent Duty Cycles and Independent Periods, No

Phase-Shifting, Center-Aligned

Figure 14-30: Redundant PWM Mode – Master Duty Cycles and Independent Periods, No Phase-Shifting,

Center-Aligned

/* Set PWM Periods on PHASEx Registers */

PHASE1 = 1000;

PHASE2 = 900;

PHASE3 = 800;

/* Set Duty Cycles */

PDC1 = 400;

PDC2 = 300;

PDC3 = 200;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 0;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 0;

/* Set PWM Mode to Redundant */

IOCON1 = IOCON2 = IOCON3 = 0xC400;

/* Set Independent Time Bases, Center-Aligned Mode and Independent Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0204;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

MDC

PHASE1

PHASE2

PHASE3

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

MDC

Start of

PWM1H Cycle

Complete

PWM1H and

PWM1L Cycle

Where:

PHASEx Period of PWMxH and PWMxL

MDC Duty Cycle of PWMxH and PWMxL

dsPIC33E/PIC24E Family Reference Manual

Example 14-29: Redundant PWM Mode – Master Duty Cycles and Independent Periods,

No Phase-shifting, Center-Aligned

Table 14-2 provides PWM register functionality for the PWM modes.

Table 14-2: Complementary, Push-Pull and Redundant Mode Register Functionality

Function

Configuration in PWMCONx Pins

MDCS ITB MTBS PWMxH PWMxL

PWM Duty Cycle 0xxPDCx PDCx

1xxMDC MDC

PWM Phase Shift x0xPHASEx PHASEx

PWM Period xx0PTPER PTPER

xx1STPER STPER

x1xPHASEx PHASEx

Legend: x = don’t care

/* Set PWM Periods on PHASEx Registers */

PHASE1 = 1000;

PHASE2 = 900;

PHASE3 = 800;

/* Set Duty Cycles */

MDC = 200;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 0;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 0;

/* Set PWM Mode to Redundant */

IOCON1 = IOCON2 = IOCON3 = 0xC400;

/* Set Independent Time Bases, Center-Aligned Mode and Master Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0304;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

dsPIC33E/PIC24E Family Reference Manual

Example 14-30: Independent PWM Mode – Independent Duty Cycle and Phase, Fixed Primary Period,

Edge-Aligned

Figure 14-32: Independent PWM Mode – Independent Duty Cycle and Phase, Fixed Secondary Period,

Edge-Aligned

/* Set PWM Period on Primary Time Base */

PTPER = 1000;

/* Set Phase Shift */

PHASE1 = 0;

SPHASE1 = 100;

PHASE2 = 200;

SPHASE2 = 300;

PHASE3 = 400;

SPHASE3 = 500;

/* Set Duty Cycles */

PDC1 = 100;

SDC1 = 200;

PDC2 = 300;

SDC2 = 400;

PDC3 = 500;

SDC3 = 600;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 0;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 0;

/* Set PWM Mode to Independent */

IOCON1 = IOCON2 = IOCON3 = 0xCC00;

/* Set Primary Time Base, Edge-Aligned Mode and Independent Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0000;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

STPER

PHASE1 = 0

SPHASE1

PHASE2

SPHASE2

PHASE3

SPHASE3

PDC1

SDC1

PDC2

SDC2

PDC3

SDC3

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

Start of

PWM Cycle

Where: PHASEx Phase of PWMxH

SPHASEx Phase of PWMxL

PDCx Duty Cycle of PWMxH

SDCx Duty Cycle of PWMxL

STPER Period of PWMxH and PWMxL

Section 14. High-Speed PWM

High-Speed PWM

Example 14-31: Independent PWM Mode – Independent Duty Cycle and Phase, Fixed Secondary Period,

Edge-Aligned

Figure 14-33: Independent PWM Mode – Master Duty Cycle, Variable Phase, Fixed Primary Period,

Edge-Aligned

/* Set PWM Period on Secondary Time Base */

STPER = 1000;

/* Set Phase Shift */

PHASE1 = 0;

SPHASE1 = 100;

PHASE2 = 200;

SPHASE2 = 300;

PHASE3 = 400;

SPHASE3 = 500;

/* Set Duty Cycles */

PDC1 = 100;

SDC1 = 200;

PDC2 = 300;

SDC2 = 400;

PDC3 = 500;

SDC3 = 600;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 0;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 0;

/* Set PWM Mode to Independent */

IOCON1 = IOCON2 = IOCON3 = 0xCC00;

/* Set Secondary Time Base, Edge-Aligned Mode and Independent Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0008;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

PTPER

PHASE1 = 0

SPHASE1

PHASE2

SPHASE2

PHASE3

SPHASE3

MDC

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

MDC

Start of

PWM Cycle

Where: PHASEx Phase of PWMxH

SPHASEx Phase of PWMxL

MDC Duty Cycle of PWMxH and PWMxL

PTPER Period of PWMxH and PWMxL

dsPIC33E/PIC24E Family Reference Manual

Example 14-32: Independent PWM Mode – Master Duty Cycle, Variable Phase, Fixed Primary Period,

Edge-Aligned

Figure 14-34: Independent PWM Mode – Master Duty Cycle, Variable Phase, Fixed Secondary Period,

Edge-Aligned

/* Set PWM Period on Primary Time Base */

PTPER = 1000;

/* Set Phase Shift */

PHASE1 = 0;

SPHASE1 = 100;

PHASE2 = 200;

SPHASE2 = 300;

PHASE3 = 400;

SPHASE3 = 500;

/* Set Duty Cycles */

MDC = 300;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 0;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 0;

/* Set PWM Mode to Independent */

IOCON1 = IOCON2 = IOCON3 = 0xCC00;

/* Set Primary Time Base, Edge-Aligned Mode and Master Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0100;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

STPER

PHASE1 = 0

SPHASE1

PHASE2

SPHASE2

PHASE3

SPHASE3

MDC

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

MDC

Start of

PWM Cycle

Where: PHASEx Phase of PWMxH

SPHASEx Phase of PWMxL

MDC Duty Cycle of PWMxH and PWMxL

STPER Period of PWMxH and PWMxL

dsPIC33E/PIC24E Family Reference Manual

Figure 14-35: Independent PWM Mode – Independent Duty Cycles and Periods, No Phase-Shifting,

Edge-Aligned

Example 14-34: Independent PWM Mode – Independent Duty Cycles and Periods, No Phase-Shifting,

Edge-Aligned

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

PDC1

SDC1

PDC2

SDC2

PDC3

SDC3

PHASE1

SPHASE1

PHASE2

SPHASE2

PHASE3

SPHASE3

Start of

PWM Cycle

Where: PHASEx Period of PWMxH

SPHASEx Period of PWMxL

PDCx Duty Cycle of PWMxH

SDCx Duty Cycle of PWMxL

/* Set PWM Periods on PHASEx Registers */

PHASE1 = 800;

SPHASE1 = 900;

PHASE2 = 1000;

SPHASE2 = 1100;

PHASE3 = 1200;

SPHASE3 = 1300;

/* Set Duty Cycles */

PDC1 = 200;

SDC1 = 300;

PDC2 = 400;

SDC2 = 500;

PDC3 = 600;

SDC3 = 700;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 0;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 0;

/* Set PWM Mode to Independent */

IOCON1 = IOCON2 = IOCON3 = 0xCC00;

/* Set Independent Time Bases, Edge-Aligned Mode and Independent Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0200;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

Section 14. High-Speed PWM

High-Speed PWM

Figure 14-36: Independent PWM Mode – Master Duty Cycles, Independent Periods, No Phase-Shifting,

Edge-Aligned

Example 14-35: Independent PWM Mode – Master Duty Cycles, Independent Periods, No Phase-Shifting,

Edge-Aligned

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

MDC

PHASE1

SPHASE1

PHASE2

SPHASE2

PHASE3

SPHASE3

Start of

PWM Cycle

Where: PHASEx Period of PWMxH

SPHASEx Period of PWMxL

MDC Duty Cycle of PWMxH and PWMxL

/* Set PWM Periods on PHASEx Registers */

PHASE1 = 800;

SPHASE1 = 900;

PHASE2 = 1000;

SPHASE2 = 1100;

PHASE3 = 1200;

SPHASE3 = 1300;

/* Set Duty Cycles */

MDC = 200;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 0;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 0;

/* Set PWM Mode to Independent */

IOCON1 = IOCON2 = IOCON3 = 0xCC00;

/* Set Independent Time Bases, Edge-Aligned Mode and Master Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0300;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

Section 14. High-Speed PWM

High-Speed PWM

Figure 14-38: Independent PWM Mode – Master Duty Cycles, Independent Periods, No Phase-Shifting,

Center-Aligned

Example 14-37: Independent PWM Mode – Master Duty Cycles, Independent Periods, No Phase-Shifting,

Center-Aligned

MDC

PHASE1

SPHASE1

PHASE2

SPHASE2

PHASE3

SPHASE3

PWM1H

PWM1L

PWM2H

PWM2L

PWM3H

PWM3L

MDC

Start of

PWM1H Cycle

Complete

PWM1H Cycle

Where: PHASEx Period of PWMxH

SPHASEx Period of PWMxL

MDC Duty Cycle of PWMxH and PWMxL

/* Set PWM Periods on PHASEx Registers */

PHASE1 = 1300;

SPHASE1 = 1200;

PHASE2 = 1100;

SPHASE2 = 1000;

PHASE3 = 900;

SPHASE3 = 800;

/* Set Duty Cycles */

MDC = 700;

/* Set Dead Time Values */

DTR1 = DTR2 = DTR3 = 0;

ALTDTR1 = ALTDTR2 = ALTDTR3 = 0;

/* Set PWM Mode to Independent */

IOCON1 = IOCON2 = IOCON3 = 0xCC00;

/* Set Independent Time Bases, Center-Aligned Mode and Master Duty Cycles */

PWMCON1 = PWMCON2 = PWMCON3 = 0x0304;

/* Configure Faults */

FCLCON1 = FCLCON2 = FCLCON3 = 0x0003;

/* 1:1 Prescaler */

PTCON2 = 0x0000;

/* Enable PWM Module */

PTCON = 0x8000;

Section 14. High-Speed PWM

High-Speed PWM

14.7 PWM GENERATOR

This section describes the functionality of the PWM generator.

14.7.1 PWM Period

The PWM period value defines the switching frequency of the PWM pulses. The PWM period

value can be controlled by the Primary Master Time Base Period register (PTPER), or by the

Independent Time Period PHASEx and SPHASEx registers for the respective primary and

secondary PWM outputs, if available.

The PWM period value can be controlled in two ways when the High-Speed PWM module

operates in Independent Time Base mode:

• In some modes, the PHASEx register controls the PWM period value of the PWM output

signals (PWMxH and PWMxL)

• In True Independent Output mode, the PHASEx register controls the PWM period value of

the PWMxH output signal, and the SPHASEx register controls the PWM period value of the

PWMxL output signal

Refer to 14.6 “PWM Operating Modes”, for detailed information about various PWM modes and

their features.

When the High-Speed PWM module operates in Master Time Base mode, the PTPER register

holds the 16-bit value, which specifies the counting period for the PMTMR timer. When the

High-Speed PWM module operates in Independent Time Base mode, the PHASEx and

SPHASEx registers hold the 16-bit value that sp riod for the PTMRx andecifies the counting pe

STMRx timer, respectively. The timer period can be updated at any time by the user-assigned

application. The PWM time period (PTPER) in Edge-Aligned PWM mode (CAM bit

(PWMCONx<2>) is set to ‘0’) can be determined by using the Equation 14-1.

Equation 14-1: PERIOD, PHASEx and SPHASEx Register Value Calculation for

Edge-Aligned Mode

Based on Equation 14-1, while operating in the master time base (PTPER register) or the

independent time base (PHASEx and SPHASEx registers), the register value to be loaded is

shown in Example 14-38.

Example 14-38: PWM Time Period Calculation for Edge-Aligned Mode

Note: Not all registers and features listed in this section are available on all devices. Refer

to the “High-Speed PWM” chapter in the specific device data sheet for availability.

Where:

PTPER, PHASEx,

SPHASEx =

FPWM

* PWM Input Clock Prescaler

FOSC

FPWM = Desired PWM frequency

FOSC = Oscillator output (120 MHz for 60 MIPS)

PWM Input Clock Prescaler = Value defined in the PCLKDIV<2:0> bits (PTCON2<2:0)

PTPER 120MHz

20 1kHz ×

-------------------------- 6000= =

Where:

PWM Input Clock Prescaler = 1:1

System Oscillator Frequency (FOSC) = 120 MHz

Desired PWM Switching Frequency = 20 kHz

dsPIC33E/PIC24E Family Reference Manual

The PWM time period (PHASEx or SPHASEx) in Center-Aligned mode (CAM = 1 and ITB = 1),

can be determined using Equation 14-2. The PTPER register does not represent the period in

Center-Aligned mode, since this mode requires independent time bases, which are enabled by

setting ITB = 1.

Equation 14-2: PHASEx or SPHASEx Register Value Calculation in Center-Aligned

Mode

Based on Equation 14-2, when operating in independent time bases (PHASEx and SPHASEx

registers), the register value to be loaded is shown in Example 14-39.

Example 14-39: PWM Time Period Calculation Example in Center-Aligned Mode

The maximum available PWM period resolution is TOSC for Edge-Aligned mode and TOSC * 2 in

Center-Aligned mode. The PCLKDIV<2:0> bits (PTCON2<2:0>), determine the type of PWM

clock. The timer/counter is enabled or disabled by setting or clearing the PTEN bit

(PTCON<15>). The PMTMR timer can also be cleared using the PTEN bit.

If the EIPU bit (PTCON<10>) is set, the active master period register (an internal shadow

the PMTMR master time base.

Example 14-40: Clock Prescaler Selection

Example 14-41: PWM Time Period Selection

Example 14-42: PWM Time Period Initialization

PHASEx, SPHASEx FOS C

FPWM PWM Input Clock Prescaler 2⋅ ⋅

-----------------------------------------------------------------------------------------------------=

PHASEx, SPHASEx 120 MHz

20 kHz 1 2⋅ ⋅

------------------------------------- 3000==

Where:

PWM Frequency (FPWM) = 20 kHz

PWM Input Clock Prescaler = 1:1

System Oscillator Frequency (FOSC) = 120 MHz

/* Select PWM time base input clock prescaler */

/* Choose divide ratio of 1:2 */

PTCON2bits.PCLKDIV = 1;

/* Select Time Base Period Control */

/* Choose one of these options */

PWMCON1bits.ITB = 0; /* PTPER provides the PWM time period value */

PWMCON1bits.ITB = 1; /* PHASEx/SPHASEx provides the PWM time period value */

/* Choose PWM time period based on FRC input clock */

/* PWM frequency is 100 kHz */

/* Choose one of the following options */

PTPER = 4808;

PHASEx = 4808;

SPHASEx = 4808;

Section 14. High-Speed PWM

High-Speed PWM

14.7.2 PWM Duty Cycle Control

The duty cycle determines the period of time the PWM output should remain in the active state.

Each duty cycle register allows a 16-bit duty cycle value to be specified. The duty cycle values

can be updated at any time by setting the IUE bit (PWMCONx<0>). If the IUE bit is ‘0’, the active

The Master Duty Cycle register (MDC) enables multiple PWM generators to share a common

duty cycle register.The MDC register has an important role in Master Time Base mode.

In addition, each PWM generator has a Primary Duty Cycle register (PDCx) and on certain

devices, a Secondary Duty Cycle register (SDCx) that provides separate duty cycles to each

PWM.

14.7.2.1 MASTER DUTY CYCLE (MDC)

The master time base generator controls the master duty cycle. The MDCS bit (PWMCONx<8>),

determines whether the duty cycle of each of the PWMxH and PWMxL outputs are controlled by

the PWM Master Duty Cycle register (MDC) or the PWM Primary Duty Cycle (PDCx) and PWM

Secondary Duty Cycle (SDCx) registers.

The MDC register enables sharing of the common duty cycle register among multiple PWM

generators and saves the CPU overhead required in updating multiple duty cycle registers.

14.7.2.2 PRIMARY DUTY CYCLE (PDCx)

The independent time base controls the primary duty cycle when the ITB bit (PWMCONx<9>) is

set to ‘1’. The PDCx register is an input register that provides the duty cycle value for the primary

PWM output signal (PWMxH).

Figure 14-39: Primary Duty Cycle Comparison

PDCx Register

PMTMR

Compare Logic PWMx Signal

MUX

MDC Register

MDCS Select

0 1

CLK

Note: In Independent Output mode, PDCx affects PWMxH only.

dsPIC33E/PIC24E Family Reference Manual

14.7.2.3 SECONDARY DUTY CYCLE (SDCx)

The independent time base in the PWMCONx register controls the Secondary Duty Cycle

the duty cycle value for the secondary PWM output signal (PWMxL).

Figure 14-40: Secondary Duty Cycle Comparison

The duty cycle can be determined by using Equation 14-3.

Equation 14-3: MDC, PDCx and SDCx Calculation

Based on Equation 14-3, when the master, independent primary, or independent secondary duty

cycle is used, the register value SDCx register, respectively.is loaded in the MDC, PDCx, or

Note: The SDCx register is not available on all devices. Refer to the “High-Speed PWM”

chapter of the specific device data sheet for availability.

Note 1: If a duty cycle value is greater than or equal to the period value, a signal will have

a duty cycle of 100 percent.

2: When dead time compensation is disabled if PDCx does not adhere to (PDCx >

((ALTDTRx/2) -1)) the PWMxH will be constantly high.

3: If PDCx > (ALTDTRx + DTRx - 1) condition is not satisfied it could result in one or

both of the below:

a) Loss of dead time.

b) PWMxH will be constantly high.

SDCx Register

STMRx

Compare Logic PWMx Signal

015

MUX

MDC Register

MDCS Select

0 1

Clk

Note: In Independent Output mode, SDCx affects PWMxL only.

MDC, PDCx, and SDCx FOSC

FPWM PWM Input Clock Prescaler⋅

------------------------------------------------------------------------------------------- Desired Duty Cycle⋅=

Where:

FPWM = PWM Frequency

FOSC = System Oscillator Output

PWM Input Clock Prescaler = Value defined in the PCLKDIV<2:0> bits (PTCON<2:0>)

Desired Duty Cycle = Value between 0 and 1 for desired duty cycle

Section 14. High-Speed PWM

High-Speed PWM

14.7.2.4 DUTY CYCLE RESOLUTION

The PWM duty cycle bit resolution for Edge-Aligned mode can be determined using

Equation 14-4, and the PWM duty cycle bit resolution for Center-Aligned mode can be

determined using Equation 14-5.

Equation 14-4: Bit Resolution Calculation for Edge-Aligned Mode

Equation 14-5: Bit Resolution Calculation for Center-Aligned Mode

Example 14-43: PWM Duty Cycle Selection

Example 14-44: PWM Duty Cycle Initialization

Bit Resolution 2FOSC

FPWM PWM Input Clock Prescaler⋅

-------------------------------------------------------------------------------------------

log=

Bit Resolution 2FOSC

FPWM PWM Input Clock Prescaler 2⋅ ⋅

-----------------------------------------------------------------------------------------------------

log=

PWMCON1bits.MDCS = 0; /* PDCx/SDCx provides duty cycle value */

PWMCON1bits.MDCS = 1; /* MDC provides duty cycle value */

/* Initialize PWM Duty Cycle Value */

PDC1 = 2404; /* Independent Primary Duty Cycle is 50% of the period */

SDC1 = 2404; /* Independent Secondary Duty Cycle is 50% of the period */

MDC = 2404; /* Master Duty Cycle is 50% of the period */

dsPIC33E/PIC24E Family Reference Manual

14.7.4.1 POSITIVE DEAD TIME

The Positive Dead Time mode describes a period of time when both PWMxH and PWMxL

outputs are not asserted. This mode is useful when the application designer needs to allocate

time to disable some power transistors prior to enabling other transistors. This is similar to a

“Break before Make” switch. When Positive Dead Time mode is specified in Edge-Aligned PWM

mode (CAM = 0), the DTRx register specifies the dead time for the PWMxH output, and the

ALTDTRx register specifies the dead time for the PWMxL output. When Center-Aligned mode is

enabled (CAM = 1), the ALTDTR register specifies the dead time, while the DTRx register is

ignored. These two modes are shown in Figure 14-43 and Figure 14-44.

Figure 14-43: Positive Dead Time in Edge-Aligned Mode and Complementary Mode

Figure 14-44: Positive Dead Time in Center-Aligned Mode and Complementary Mode

14.7.4.2 NEGATIVE DEAD TIME

The Negative Dead Time mode describes a period of time when both PWMxH and PWMxL

outputs are asserted. This mode is useful in current fed topologies that need to provide a path

for current to flow when the power transistors are switching. This is similar to a “Make before

Break” switch. When Negative Dead Time mode is specified in Edge-Aligned mode, the DTRx

specifies the negative dead time for the PWMxH output. When Center-Aligned mode is enabled

(CAM = 1), negative dead time is not supported, and the ALTDTRx and DTRx registers are

ignored. This mode is shown in Figure 14-45.

Figure 14-45: Negative Dead Time in Edge-Aligned Mode and Complementary Mode

PWMxH

PWMxL

Start of

PWM Cycle

DTRx

PDCx or MDC

ALTDTRx

Period Register (PTPER,

STPER or PHASEx)

PWMxH

PWMxL

Start of

PWM Cycle

PDCx or MDC

-ALTDTRx/2

Period Register (PTPER,

STPER or PHASEx)

ALTDTRx/2

Complete PWMxH

and PWMxL Cycle

ALTDTRx/2

ALTDTRx/2ALTDTRx/2

PWMxH

PWMxL

Start of

PWM Cycle

DTRx

PDCx or MDC

ALTDTRx

Period Register (PTPER,

STPER or PHASEx)

Section 14. High-Speed PWM

High-Speed PWM

14.7.4.3 DEAD TIME COMPENSATION

When dead time is applied to the PWM signals in AC motor control applications, the transistors

are disabled. During dead time, motor current continues to flow through the free-wheeling

diodes, but the applied voltage is zero. The zero applied voltage during dead time causes a

distortion of the desired voltage waveform and subsequently a motor current distortion. This

distortion causes torque variations that can affect the stability of the control system, and the

performance of the motor.

Dead Time Compensation mode enables an external signal (DTCMPx) to modify the duty cycle

to overcome motor current distortion caused by the dead time.

When Dead Time Compensation mode is selected via the DTC<1:0> bits (PWMCONx<7:6>), an

external input signal (DTCMPx) will cause the value in the DTRx register to be added to, or

subtracted from, the duty cycle specified by the PDCx or MDC registers. The ALTDTRx register

will specify the dead time for both the PWMxH and PWMxL output signals.

Dead time compensation is available only for Complementary PWM output mode with Positive

Dead Time mode. Negative dead times or any other PWM output mode are not supported by

Dead Time Compensation mode.

Figure 14-46: Dead Time Compensation in Edge-Aligned Mode (DTCMPx Pin = 0 and DTCP = 0 or DTCMPx

Pin = 1 and DTCP = 1)

PWMxH

PWMxL

Start of

PWM Cycle

PDCx

DTRx

PDCx – DTRx

ALTDTRx = 0

PDCx – DTRx

– ALTDTRx

ALTDTRx ALTDTRx

PWMxH

PWMxL

PWMxH

PWMxL

Period Register (PTPER, STPER or PHASEx)

DTRx = 0

ALTDTRx = 0

DTRx 0

ALTDTRx = 0

DTRx ≠ 0

ALTDTRx ≠ 0

≠

Section 14. High-Speed PWM

High-Speed PWM

Figure 14-48: Dead Time Compensation in Center-Aligned Mode (DTCMPx Pin = 0 and DTCP = 0 or DTCMPx

Pin = 1 and DTCP = 1)

PWMxH

PWMxL

Start of

PWM Cycle

PDCx

DTRx

PDCx – DTRx

ALTDTRx = 0

PWMxH

PWMxL

PWMxH

PWMxL

Period Register PHASEx

Complete PWMxH and PWMxL Cycle

ALTDTRx/2 ALTDTRx/2

PDCx – DTRx

– ALTDTRx/2

DTRx = 0

ALTDTRx = 0

DTRx ≠ 0

ALTDTRx = 0

DTRx ≠ 0

ALTDTRx ≠ 0

ALTDTRx/2

dsPIC33E/PIC24E Family Reference Manual

14.7.8 Phase Shift

Phase shift is the relative offset between PWMxH or PWMxL with respect to the master time

base. In Independent Output mode, the PHASEx register determines the relative phase shift

between PWMxH and the master time base. The SPHASEx register determines the relative

phase shift between PWMxL and the master time base. The contents of the PHASEx register are

used as an initialization value for the PTMRx register, and the SPHASEx register contents are

used as an initialization value for the STMRx register.

Figure 14-51 and Figure 14-52 provide example waveforms for phase shifting in Complementary

mode and Independent Output mode, respectively.

Figure 14-51: Phase Shifting (Complementary Mode)

Figure 14-52: Phase Shifting (Independent Output Mode)

In addition, there are two shadow registers for the PHASEx and SPHASEx registers that are

updated whenever new values are written by the user-assigned application. These values are

transferred from the shadow registers to the PHASEx and SPHASEx registers on an

independent time base Reset. The actual application of these phase offsets on the PWM output

will occur on a master time base Reset.

Note: The SPHASEx register is not available on all devices. Refer to the “High-Speed

PWM” chapter in the specific device data sheet for availability.

PWMxH without Phase Shift

PWMxH with Phase Shift

PWMxL without Phase Shift

PWMxL with Phase Shift

PHASEx

PWMxH without Phase Shift

PWMxH with Phase Shift

PWMxL without Phase Shift

PWMxL with Phase Shift

(Different Duty Cycle)

PHASEx

SPHASEx

Produkt Specifikationer

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Model:	dsPIC33EV256GM003

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