Datasheet

 2009-2012 Microchip Technology Inc. DS70591E-page 229
dsPIC33FJ32GS406/606/608/610 and dsPIC33FJ64GS406/606/608/610
16.0 HIGH-SPEED PWM
The High-Speed PWM module on
the dsPIC33FJ32GS406/606/608/610 and
dsPIC33FJ64GS406/606/608/610 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:
• Two Master Time Base modules
• Up to Nine PWM Generators with up to 18 Outputs
• Two PWM Outputs per PWM Generator
• Individual Time Base and Duty Cycle for each
PWM Output
• Duty Cycle, Dead Time, Phase Shift and
Frequency Resolution of 1.04 ns
• Independent Fault and Current-Limit Inputs for
Eight PWM Outputs
• Redundant Output
• True Independent Output
• Center-Aligned PWM mode
• Output Override Control
• Chop mode (also known as Gated mode)
• Special Event Trigger
• Prescaler for Input Clock
• Dual Trigger from PWM to Analog-to-Digital
Converter (ADC) per PWM Period
• PWMxL and PWMxH Output Pin Swapping
• Independent PWM Frequency, Duty Cycle and
Phase Shift Changes
• Current Compensation
• 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 PWM
output pair for the Complementary PWM mode.
The PWM module contains nine PWM generators. The
module has up to 18 PWM output pins: PWM1H/
PWM1L through PWM9H/PWM9L. For complementary
outputs, these 18 I/O pins are grouped into high/low
pairs.
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
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 Con-
verter 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 1: This data sheet summarizes the features
of the dsPIC33FJ32GS406/606/608/610
and dsPIC33FJ64GS406/606/608/610
families of devices. It is not intended to be
a comprehensive reference source. To
complement the information in this data
sheet, refer to Section 43. “High-Speed
PWM” (DS70323) in the “dsPIC33F/
PIC24H Family Reference Manual”,
which is available from the Microchip web
site (www.microchip.com).
2: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
Section 4.0 “Memory Organization” in
this data sheet for device-specific register
and bit information.
Note: Duty cycle, dead-time, phase shift and
frequency resolution is 8.32 ns in
Center-Aligned PWM mode.