Microchip Technology DM164134 Data Sheet

© 2006 Microchip Technology Inc.

DS41159E-page 253

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.

A device Reset forces the CMCON register to its Reset
state, causing the comparator module to be in the
Comparator Reset mode, CM<2:0> = 000. This
ensures that all potential inputs are analog inputs.
Device current is minimized when analog inputs are
present at Reset time. The comparators will be
powered down during the Reset interval. 

A simplified circuit for an analog input is shown in
Figure 21-4. Since the analog pins are connected to a
digital output, they have reverse biased diodes to V

DD

and V

SS

. The analog input, therefore, must be between

V

SS

 and V

DD

. 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

Ω 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.

VA

R

S

 < 10k

A

IN

C

PIN

5 pF

V

DD

V

T

 = 0.6V

V

T

 = 0.6V

R

IC

I 

LEAKAGE

±500 nA

V

SS

C

PIN

=

Input Capacitance

V

T

= Threshold 

Voltage

I 

LEAKAGE

= 

Leakage Current at the pin due to various junctions

R

IC

=

Interconnect Resistance

R

S

= 

Source Impedance

VA

= 

Analog Voltage