Datasheet

 2011-2012 Microchip Technology Inc. Preliminary DS41579D-page 177
PIC16(L)F1782/3
20.7 Comparator Negative Input
Selection
The CxNCH<2:0> bits of the CMxCON0 register direct
an analog input pin or analog ground to the inverting
input of the comparator:
•CxIN- pin
• Analog Ground
Some inverting input selections share a pin with the
operational amplifier output function. Enabling both
functions at the same time will direct the operational
amplifier output to the comparator inverting input.
20.8 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
Reference Specifications in
Section 30.0 “Electrical
Specifications”
for more details.
20.9 Zero Latency Filter
In high-speed operation, and under proper circuit
conditions, it is possible for the comparator output to
oscillate. This oscillation can have adverse effects on
the hardware and software relying on this signal.
Therefore, a digital filter has been added to the
comparator output to suppress the comparator output
oscillation. Once the comparator output changes, the
output is prevented from reversing the change for a
nominal time of 20 ns. This allows the comparator
output to stabilize without affecting other dependent
devices. Refer to Figure 20-3.
FIGURE 20-3: COMPARATOR ZERO LATENCY FILTER OPERATION
Note: To use CxINy+ and CxINy- 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.
CxOUT From Comparator
CxOUT From ZLF
TZLF
Output waiting for TZLF to expire before an output change is allowed
T
ZLF has expired so output change of ZLF is immediate based on
comparator output change