PIC18F1230 Datasheet, PDF (177/312 Pages) Microchip Technology – 18/20/28-Pin, Enhanced Flash Microcontrollers with nanoWatt Technology, High-Performance PWM and A/D

PIC18F1230/1330
16.7 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.
Each operational comparator will consume additional
current, as shown in the comparator specifications. To
minimize power consumption while in Sleep mode, turn
off the comparators (CMEN2:CMEN0 = 000) before
entering Sleep. If the device wakes up from Sleep, the
contents of the CMCON register are not affected.
16.8 Effects of a Reset
A device Reset forces the CMCON register to its Reset
state, causing the comparator modules to be turned off
(CMEN2:CMEN0 = 000).
16.9 Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 16-2. 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 Zener diode, should have very little
leakage current.
FIGURE 16-2:
COMPARATOR ANALOG INPUT MODEL
RS < 10k
AIN
VA
CPIN
5 pF
VDD
VT = 0.6V
VT = 0.6V
RIC
ILEAKAGE
±500 nA
Comparator
Input
VSS
Legend:
CPIN
=
VT
=
ILEAKAGE =
RIC
=
RS
=
VA
=
Input Capacitance
Threshold Voltage
Leakage Current at the pin due to various junctions
Interconnect Resistance
Source Impedance
Analog Voltage
© 2006 Microchip Technology Inc.
Advance Information
DS39758B-page 175