PIC18F25J50 MICROCHIP [Microchip Technology], PIC18F25J50 Datasheet - Page 388

• Manufacturer Part Number: PIC18F25J50
• Description: 28/44-Pin, Low-Power, High-Performance USB Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F46J50 FAMILY
23.5
Each comparator has up to eight possible combina-
tions of inputs: up to four external analog inputs and
one of two internal voltage references.
Both comparators allow a selection of the signal from
pin, CxINA, or the voltage from the comparator refer-
ence (CV
compared to either CxINB, CTMU or the microcon-
troller’s fixed internal reference voltage (V
nominal) on the inverting channel.
Table 23-1
tied to fixed I/O pins.
TABLE 23-1:
23.5.1
Setting the CON bit of the CMxCON register
(CMxCON<7>) enables the comparator for operation.
Clearing the CON bit disables the comparator, resulting
in minimum current consumption.
The CCH<1:0> bits in the CMxCON register
(CMxCON<1:0>) direct either one of three analog input
pins, or the Internal Reference Voltage (V
comparator, V
ating mode, either an external or internal voltage
reference may be used. The analog signal present at
V
output of the comparator is adjusted accordingly.
DS39931D-page 388
IN
Comparator
- is compared to the signal at V
1
2
Comparator Control and
Configuration
REF
provides the comparator inputs and outputs
COMPARATOR ENABLE AND
INPUT SELECTION
) on the non-inverting channel. This is
IN
-. Depending on the comparator oper-
COMPARATOR INPUTS AND
OUTPUTS
Input or Output
C1INA (V
C1INB (V
C2INA(V
C2INB(V
C1OUT
C2OUT
IN
IN
IN
IN
+)
+)
-)
-)
IN
+ and the digital
Remapped
Remapped
I/O Pin
IRV
RA0
RA3
RPn
RA1
RA2
RPn
IRV
), to the
, 0.6V
The external reference is used when CREF = 0
(CMxCON<2>) and V
pin. When external voltage references are used, the
comparator module can be configured to have the
reference sources externally. The reference signal
must be between V
either pin of the comparator.
The comparator module also allows the selection of an
internally generated voltage reference (CV
the comparator voltage reference module. This module
is described in more detail in
tor
voltage reference module is only available when
CREF = 1. In this mode, the internal voltage reference
is applied to the comparator’s V
23.5.2
The comparator outputs are read through the CMSTAT
register. The CMSTAT<0> bit reads the Comparator 1
output and CMSTAT<1> bit reads the Comparator 2
output. These bits are read-only.
The comparator outputs may also be directly output to
the RPn I/O pins by setting the COE bit (CMxCON<6>).
When enabled, multiplexers in the output path of the
pins switch to the output of the comparator.
By default, the comparator’s output is at logic high
whenever the voltage on V
The polarity of the comparator outputs can be inverted
using the CPOL bit (CMxCON<5>).
The uncertainty of each of the comparators is related to
the input offset voltage and the response time given in
the specifications, as discussed in
“Comparator
Note:
Module”. The reference from the comparator
The comparator input pin selected by
CCH<1:0> must be configured as an input
by setting both the corresponding TRIS
and PCFG bits in the ANCON1 register.
COMPARATOR ENABLE AND
OUTPUT SELECTION
Operation”.
SS
IN
and V
 2011 Microchip Technology Inc.
+ is connected to the CxINA
IN
DD
Section 23.0 “Compara-
+ is greater than on V
, and can be applied to
IN
+ pin.
Section 23.2
REF
) from
IN
-.