PIC12F635/PIC16F636/639
comparator is a digital low level. When the analog
voltage at VIN+ is greater than the analog voltage at
VIN-, the output of the comparator is a digital high level.
7.0
COMPARATOR MODULE
Comparators are used to interface analog circuits to a
digital circuit by comparing two analog voltages and
providing a digital indication of their relative magnitudes.
The comparators are very useful mixed signal building
blocks because they provide analog functionality
independent of the program execution. The Analog
Comparator module includes the following features:
The PIC12F635 contains a single comparator as
shown in Figure 7-2.
The PIC16F636/639 devices contains two comparators
as shown in Figure 7-3 and Figure 7-4. The comparators
are not independently configurable.
• Dual comparators (PIC16F636/639 only)
• Multiple comparator configurations
FIGURE 7-1:
SINGLE COMPARATOR
• Comparator(s) output is available
internally/externally
VIN+
VIN-
+
Output
• Programmable output polarity
• Interrupt-on-change
–
• Wake-up from Sleep
• Timer1 gate (count enable)
• Output synchronization to Timer1 clock input
• Programmable voltage reference
VIN-
VIN+
7.1
Comparator Overview
A comparator is shown in Figure 7-1 along with the
relationship between the analog input levels and the
digital output. When the analog voltage at VIN+ is less
than the analog voltage at VIN-, the output of the
Output
Note:
The black areas of the output of the
comparator represents the uncertainty
due to input offsets and response time.
FIGURE 7-2:
COMPARATOR OUTPUT BLOCK DIAGRAM (PIC12F635)
CMSYNC
To Timer1 Gate
To COUT pin
CINV
0
1
D
Q
Timer1
clock source
(1)
To Data Bus
Set CMIF bit
D
Q
Q
Q1
EN
RD CMCON0
D
Q3*RD CMCON0
EN
CL
Reset
Note 1: Comparator output is latched on falling edge of Timer1 clock source.
2: Q1 and Q3 are phases of the four-phase system clock (FOSC).
3: Q1 is held high during Sleep mode.
© 2007 Microchip Technology Inc.
DS41232D-page 71
MICROCHIP [ MICROCHIP ]
