Datasheet

 2003-2013 Microchip Technology Inc. DS30498D-page 165
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
V
SS 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 k 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
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,
10Bh,18Bh
INTCON GIE 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.
VA
R
S < 10K
A
IN
CPIN
5 pF
V
DD
VT = 0.6V
V
T = 0.6V
R
IC
ILEAKAGE
±500 nA
V
SS
Legend: CPIN = Input Capacitance
V
T = Threshold Voltage
ILEAKAGE = Leakage Current at the pin due to various junctions
R
IC = Interconnect Resistance
R
S = Source Impedance
VA = Analog Voltage