PIC16F737-I Datasheet, PDF (167/276 Pages) Microchip Technology – 28/40/44-Pin, 8-Bit CMOS Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

PIC16F7X7
13.7 Comparator Operation
During Sleep
When a comparator is active and the device is placed
in Sleep mode, the comparator remains active and the
interrupt is functional if enabled. This interrupt will
wake-up the device from Sleep mode when enabled.
While the comparator is powered up, higher Sleep
currents than shown in the power-down current
specification will occur. Each operational comparator
will consume additional current as shown in the com-
parator specifications. To minimize power consumption
while in Sleep mode, turn off the comparators
(CM<2:0> = 111) before entering Sleep. If the device
wakes up from Sleep, the contents of the CMCON
register are not affected.
13.8 Effects of a Reset
A device Reset forces the CMCON register to its Reset
state, causing the comparator module to be in the
Comparator Off mode, CM<2:0> = 111. This ensures
compatibility to the PIC16F87X devices.
13.9 Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 13-4. Since the analog pins are connected to a
digital output, they have reverse biased diodes to VDD
and VSS. The analog input, therefore, must be between
VSS and VDD. If the input voltage deviates from this
range by more than 0.6V in either direction, one of the
diodes is forward biased and a latch-up condition may
occur. A maximum source impedance of 10 kΩ is
recommended for the analog sources. Any external
component connected to an analog input pin, such as
a capacitor or a Zener diode, should have very little
leakage current.
FIGURE 13-4:
ANALOG INPUT MODEL
VDD
RS < 10K
VT = 0.6V
AIN
VA
CPIN
5 pF
VT = 0.6V
RIC
ILEAKAGE
±500 nA
Legend:
CPIN
=
VT
=
ILEAKAGE =
RIC
=
RS
=
VA
=
VSS
Input Capacitance
Threshold Voltage
Leakage Current at the pin due to various junctions
Interconnect Resistance
Source Impedance
Analog Voltage
TABLE 13-1: REGISTERS ASSOCIATED WITH COMPARATOR MODULE
Address Name
Bit 7
Bit 6
Bit 5 Bit 4 Bit 3 Bit 2
Bit 1
Bit 0
Value on
POR
Value on
all other
Resets
9Ch
CMCON C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0111 0000 0111
9Dh
CVRCON CVREN CVROE CVRR — CVR3 CVR2 CVR1 CVR0 000- 0000 000- 0000
0Bh, 8Bh, INTCON GIE
10Bh,18Bh
PEIE TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Dh
PIR2
OSFIF CMIF LVDIF — BCLIF — CCP3IF CCP2IF 000- 0-00 000- 0-00
8Dh
PIE2
OSFIE CMIE LVDIE — BCLIE — CCP3IE CCP2IE 000- 0-00 000- 0-00
05h
PORTA
RA7
RA6
RA5 RA4 RA3 RA2
RA1
RA0 xx0x 0000 uu0u 0000
85h
TRISA PORTA Data Direction Register
1111 1111 1111 1111
Legend: x = unknown, u = unchanged, — = unimplemented, read as ‘0’. Shaded cells are unused by the comparator module.
 2004 Microchip Technology Inc.
DS30498C-page 165