DSPIC30F1010_14 Datasheet, PDF (107/286 Pages) Microchip Technology – 28/44-Pin dsPIC30F1010/202X Enhanced Flash

12.0 POWER SUPPLY PWM
The Power Supply PWM (PS PWM) module on the
dsPIC30F1010/202X device supports a wide variety of
PWM modes and output formats. This PWM module is
ideal for power conversion applications such as:
• DC/DC converters
• AC/DC power supplies
• Uninterruptable Power Supply (UPS)
12.1 Features Overview
The PS PWM module incorporates these features:
• Four PWM generators with eight I/O
• Four Independent time bases
• Duty cycle resolution of 1.1 nsec @ 30 MIPS
• Dead-time resolution of 4.2 nsec @ 30 MIPS
• Phase-shift resolution of 4.2 nsec @ 30 MIPS
• Frequency resolution of 8.4 nsec @ 30 MIPS
• Supported PWM modes:
- Standard Edge-Aligned PWM
- Complementary PWM
- Push-Pull PWM
- Multi-Phase PWM
- Variable Phase PWM
- Fixed Off-Time PWM
- Current Reset PWM
- Current-Limit PWM
- Independent Time Base PWM
• On-the-Fly changes to:
- PWM frequency
- PWM duty cycle
- PWM phase shift
• Output override control
• Independent current-limit and Fault inputs
• Special event comparator for scheduling other
peripheral events
• Each PWM generator has comparator for
triggering ADC conversions.
Figure 12-1 conceptualizes the PWM module in a sim-
plified block diagram. Figure 12-2 illustrates how the
module hardware is partitioned for each PWM output
pair for the Complementary PWM mode. Each func-
tional unit of the PWM module is discussed in
subsequent sections.
The PWM module contains four PWM generators. The
module has eight PWM output pins: PWM1H, PWM1L,
PWM2H, PWM2L, PWM3H, PWM3L, PWM4H and
PWM4L. For complementary outputs, these eight I/O
pins are grouped into H/L pairs.
dsPIC30F1010/202X
12.2 Description
The PWM module is designed for applications that
require (a) high resolution at high PWM frequencies,
(b) the ability to drive standard push-pull or half bridge
converters or (c) the ability to create multi-phase 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.
Multi-Phase 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 µsec. But an array of four PWM
channels, staggered by 1 µsec each, yields an effective
switching frequency of 1 MHz. Multi-phase PWM appli-
cations typically use a fixed-phase relationship.
Variable Phase PWM is useful in Zero Voltage Transi-
tion (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: The PLL must be enabled for the PS PWM
module to function. This is achieved by using the
FNOSC<1:0> bits in the FOSCSEL Configuration
register.
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DS70000178D-page 107