PIC16LF18854 Datasheet, PDF (298/668 Pages) Microchip Technology – C Compiler Optimized RISC Architecture

PIC16(L)F18856/76
20.5 Dead-Band Control
The dead-band control provides non-overlapping PWM
signals to prevent shoot-through current in PWM
switches. Dead-band operation is employed for Half-
Bridge and Full-Bridge modes. The CWG contains two
6-bit dead-band counters. One is used for the rising
edge of the input source control in Half-Bridge mode or
for reverse dead-band Full-Bridge mode. The other is
used for the falling edge of the input source control in
Half-Bridge mode or for forward dead band in Full-
Bridge mode.
Dead band is timed by counting CWG clock periods
from zero up to the value in the rising or falling dead-
band counter registers. See CWGxDBR and
CWGxDBF registers, respectively.
20.5.1
DEAD-BAND FUNCTIONALITY IN
HALF-BRIDGE MODE
In Half-Bridge mode, the dead-band counters dictate
the delay between the falling edge of the normal output
and the rising edge of the inverted output. This can be
seen in Figure 20-9.
20.5.2
DEAD-BAND FUNCTIONALITY IN
FULL-BRIDGE MODE
In Full-Bridge mode, the dead-band counters are used
when undergoing a direction change. The MODE<0>
bit of the CWGxCON0 register can be set or cleared
while the CWG is running, allowing for changes from
Forward to Reverse mode. The CWGxA and CWGxC
signals will change immediately upon the first rising
input edge following a direction change, but the modu-
lated signals (CWGxB or CWGxD, depending on the
direction of the change) will experience a delay dictated
by the dead-band counters. This is demonstrated in
Figure 20-3.
20.6 Rising Edge and Reverse Dead
Band
CWGxDBR controls the rising edge dead-band time at
the leading edge of CWGxA (Half-Bridge mode) or the
leading edge of CWGxB (Full-Bridge mode). The
CWGxDBR value is double-buffered. When EN = 0,
the CWGxDBR register is loaded immediately when
CWGxDBR is written. When EN = 1, then software
must set the LD bit of the CWGxCON0 register, and the
buffer will be loaded at the next falling edge of the CWG
input signal. If the input source signal is not present for
enough time for the count to be completed, no output
will be seen on the respective output.
20.7 Falling Edge and Forward Dead
Band
CWGxDBF controls the dead-band time at the leading
edge of CWGxB (Half-Bridge mode) or the leading
edge of CWGxD (Full-Bridge mode). The CWGxDBF
value is double-buffered. When EN = 0, the
CWGxDBF register is loaded immediately when
CWGxDBF is written. When EN = 1 then software
must set the LD bit of the CWGxCON0 register, and
the buffer will be loaded at the next falling edge of the
CWG input signal. If the input source signal is not
present for enough time for the count to be completed,
no output will be seen on the respective output.
Refer to Figure 20.6 and Figure 20-7 for examples.
DS40001824A-page 298
Preliminary
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