PIC18F67J11T-I Datasheet, PDF (227/466 Pages) Microchip Technology – 64/80-Pin, High-Performance, 1-Mbit Flash Microcontrollers

PIC18F87J11 FAMILY
19.4.4 HALF-BRIDGE MODE
In the Half-Bridge Output mode, two pins are used as
outputs to drive push-pull loads. The PWM output
signal is output on the P1A pin, while the complemen-
tary PWM output signal is output on the P1B pin
(Figure 19-4). This mode can be used for half-bridge
applications, as shown in Figure 19-5, or for full-bridge
applications, where four power switches are being
modulated with two PWM signals.
In Half-Bridge Output mode, the programmable
dead-band delay can be used to prevent shoot-through
current in half-bridge power devices. The value of bits
P1DC6:P1DC0 sets the number of instruction cycles
before the output is driven active. If the value is greater
than the duty cycle, the corresponding output remains
inactive during the entire cycle. See Section 19.4.6
“Programmable Dead-Band Delay” for more details
on dead-band delay operations.
Since the P1A and P1B outputs are multiplexed with
the PORTC<2> and PORTE<6> data latches, the
TRISC<2> and TRISE<6> bits must be cleared to
configure P1A and P1B as outputs.
FIGURE 19-4:
HALF-BRIDGE PWM
OUTPUT
Period
Period
P1A⁽²⁾
Duty Cycle
td
td
P1B⁽²⁾
(1)
(1)
(1)
td = Dead Band Delay
Note 1: At this time, the TMR2 register is equal to the
PR2 register.
2: Output signals are shown as active-high.
FIGURE 19-5:
EXAMPLES OF HALF-BRIDGE OUTPUT MODE APPLICATIONS
V+
Standard Half-Bridge Circuit (“Push-Pull”)
PIC18F87J11
FET
Driver
+
P1A
V
-
FET
Driver
P1B
Load
+
V
-
Half-Bridge Output Driving a Full-Bridge Circuit
PIC18F87J11
P1A
P1B
FET
Driver
FET
Driver
V-
V+
Load
V-
FET
Driver
FET
Driver
 2007-2012 Microchip Technology Inc.
DS39778E-page 227