Datasheet

 2011 Microchip Technology Inc. Preliminary DS41615A-page 135
PIC12(L)F1501
17.7 Comparator Negative Input
Selection
The CxNCH<1:0> bits of the CMxCON0 register direct
one of the input sources to the comparator inverting
input.
17.8 Comparator Response Time
The comparator output is indeterminate for a period of
time after the change of an input source or the selection
of a new reference voltage. This period is referred to as
the response time. The response time of the comparator
differs from the settling time of the voltage reference.
Therefore, both of these times must be considered when
determining the total response time to a comparator
input change. See the Comparator and Voltage Refer-
ence Specifications in
Section 27.0 “Electrical Specifi-
cations”
for more details.
17.9 Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 17-3. Since the analog input pins share their
connection with a digital input, they have reverse
biased ESD protection diodes to V
DD 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 for-
ward biased and a latch-up may occur.
A maximum source impedance of 10 k
 is recommended
for the analog sources. Also, any external component
connected to an analog input pin, such as a capacitor or
a Zener diode, should have very little leakage current to
minimize inaccuracies introduced.
Note: To use CxIN+ and CxINx- pins as analog
input, the appropriate bits must be set in
the ANSEL register and the correspond-
ing TRIS bits must also be set to disable
the output drivers.
Note 1: When reading a PORT register, all pins
configured as analog inputs will read as a
‘0’. Pins configured as digital inputs will
convert as an analog input, according to
the input specification.
2: Analog levels on any pin defined as a
digital input, may cause the input buffer to
consume more current than is specified.