Introduction to Digital Power Conversion
XMC4000/1000 Family
PWM Generation
Application Guide 32 V1.0, 2015-01
4.9 Phase Shift Control
There are two types:
Fixed Phase Shift (180
o
, 120
o
, 90
o
, and so on)
Variable Phase Shift
Fixed Phase Shift
This is used for interleave applications with multi-phase converters. The interleave function has the
benefit of overlapping discontinuities in the current path, reducing ripple and therefore allowing for
higher frequency and smaller components. EMC quality is also improved.
Variable Phase Shift
This is used for DC/DC conversion applications, and for energy transfer adaption and isolation, by
using a transformer in the path. The changes in the phase-shift modify the power transfer from
primary to secondary.
4.10 Fixed Phase-Shift
4.10.1 Center Aligned Mode
Dual PWM channels with guaranteed 180
o
fixed phase-shift even during the PWM update, is provided
by a single CCU8 slice in symmetric compare mode for two PWM channel outputs: OUT01, OUT02.
Passive/Active Level:
− for OUT01 is “ACTIVE HIGH”
− for OUT02 is “ACTIVE LOW”
Figure 21 Fixed Phase-Shift – Using a CC8-Slice in Center Aligned Symmetric Compare Mode
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