Datasheet

dsPIC33FJ06GS101/X02 and dsPIC33FJ16GSX02/X04

15.2 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

For Center-Aligned mode, the duty cycle, period phase

and dead-time resolutions will be 8.32 ns.

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 μs, but an array of four

PWM channels, staggered by 1 μs 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.