DSPIC33EP128GS708 datasheet(189/484 Pages) MICROCHIP

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 2016-2018 Microchip Technology Inc.

DS70005258C-page 189

dsPIC33EPXXXGS70X/80X FAMILY

16.0 HIGH-SPEED PWM

The high-speed PWM on dsPIC33EPXXXGS70X/80X

devices supports a wide variety of PWM modes and

output formats. This PWM module is ideal for power

conversion applications, such as:

• AC/DC Converters

• DC/DC Converters

• Power Factor Correction

• Uninterruptible Power Supply (UPS)

• Inverters

• Battery Chargers

• Digital Lighting

16.1

Features Overview

The high-speed PWM module incorporates the

following features:

• Eight PWMx Generators with Two Outputs per

Generator

• Two Master Time Base modules

• Individual Time Base and Duty Cycle for each

PWM Output

• Duty Cycle, Dead Time, Phase Shift and a

Frequency Resolution of 1.04 ns

• Independent Fault and Current-Limit Inputs

• Redundant Output

• True Independent Output

• Center-Aligned PWM mode

• Output Override Control

• Chop mode (also known as Gated mode)

• Special Event Trigger

• Dual Trigger from PWMx to Analog-to-Digital

Converter (ADC)

• PWMxL and PWMxH Output Pin Swapping

• Independent PWMx Frequency, Duty Cycle and

Phase-Shift Changes

• Enhanced Leading-Edge Blanking (LEB) Functionality

• PWM Capture Functionality

Figure 16-1 conceptualizes the PWM module in a

simplified block diagram. Figure 16-2 illustrates how

the module hardware is partitioned for each PWMx

output pair for the Complementary PWM mode.

The PWM module contains eight PWM generators. The

module has up to 16 PWMx output pins: PWM1H/

PWM1L through PWM8H/PWM8L. For complementary

outputs, these 16 I/O pins are grouped into high/low

pairs. PWM1 through PWM6 can be used to trigger an

ADC conversion.

16.2

Feature Description

The PWM module is designed for applications that

require:

• High resolution at high PWM frequencies

• The ability to drive Standard Edge-Aligned,

Center-Aligned, Complementary mode and

Push-Pull mode outputs

• The ability to create multiphase PWM outputs

Two common, medium power converter topologies are

push-pull and half-bridge. These designs require the

PWM output signal to be switched between alternate

pins, as provided by the Push-Pull PWM mode.

Phase-shifted PWM describes the situation where

each PWM generator provides outputs, but the phase

relationship between the generator outputs is

specifiable and changeable.

Multiphase PWM is often used to improve DC/DC

Converter load transient response, and reduce the size

of output filter capacitors and inductors. Multiple DC/DC

Converters are often operated in parallel, but phase

shifted in time. A single PWM output, operating at

250 kHz, has a period of 4

s but an array of four PWM

channels, staggered by 1

s each, yields an effective

switching frequency of 1 MHz. Multiphase PWM

applications typically use a fixed-phase relationship.

Variable phase PWM is useful in Zero Voltage

Transition (ZVT) power converters. Here, the PWM

duty cycle is always 50% and the power flow is

controlled by varying the relative phase shift between

the two PWM generators.

Note:

This data sheet summarizes the features

of the dsPIC33EPXXXGS70X/80X family

of devices. It is not intended to be a

comprehensive reference source. To

complement the information in this data

sheet, refer to “High-Speed PWM

Module” (DS70000323) in the “dsPIC33/

PIC24 Family Reference Manual”, which

is available from the Microchip website

(www.microchip.com).

Note:

Duty cycle, dead time, phase shift and

frequency resolution is 8.32 ns in

Center-Aligned PWM mode.

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