PIC16C782 Microchip Technology Inc., PIC16C782 Datasheet - Page 104

• Manufacturer Part Number: PIC16C782
• Description: 8-bit Cmos Microcontrollers With A/d, D/a, Opamp, Comparators And Psmc
• Manufacturer: Microchip Technology Inc.

PIC16C781/782
13.1.1
In PSM (Pulse Skip Modulation), the PSMC operates
as a fixed duty cycle pulse generator, with its output
gated by the analog feedback (see Figure 13-3). Imme-
diately prior to the initiation of a pulse, the analog feed-
back is sampled. If the comparator output = H, a pulse
is initiated and held active for the programmed duty
FIGURE 13-3:
TABLE 13-3:
Legend: x = Don’t Care
DS41171A-page 102
Beginning of PSM cycle
During Pulse
End of Pulse
SMCCL1
SMCCL0
F
OSC
PULSE SKIP MODULATION (PSM)
C1POL
C2POL
Comparator Module
Time
:1
DC<1:0>
C1
C2
S1
3
PSMC1A OPERATION IN PSM MODE USING C1 COMPARATOR ONLY
S0
:2
2
PSMC MODULE IN SINGLE OUTPUT PSM MODE (SIMPLIFIED BLOCK
DIAGRAM)
:4
PSMC
CLK
1
0 = Inactive
2
:8
0
Controller
4-bit Counter
PSMC
Switch
4
Cycle
New
C1OUT
SMCCS
C2OUT
Max
DC
SC
1 = Active
C1OUT
H
L
x
x
DC = Duty Cycle
New Cycle
Select DC
SC Switch
C1OUT
RB6/C1/
PSMC1A
RB7/C2/
PSMC1B/T1G
EXAMPLE
Preliminary
H = High
ASSUMES S1APOL=0
cycle. If the comparator output = L, no pulse is initiated
and the PSMC waits for the start of the next pulse (see
Table 13-3 and Table 13-4). In this mode, both the fre-
quency and duty cycle of the output pulse are program-
mable. The analog feedback gates the presence or
absence of the pulse on a pulse-by-pulse basis.
Programmed DC
SCEN
L = Low
S1APOL
SMCCS=0
HIGH IMPEDANCE
S
Dominant
R
PSMC1A Output Signal
Set
15/16 Period
Q
Period
No Change
SCEN=1
SMCON=1 SMCOM=0
0
1
V
0
1
DD
N
1
0
2001 Microchip Technology Inc.
PWM/PSM=0
RB6/C1/PSMC1A
RB7/C2/PSMC1B/T1G
HIGH IMPEDANCE