PIC18F25K80 MICROCHIP [Microchip Technology], PIC18F25K80 Datasheet - Page 385

• Manufacturer Part Number: PIC18F25K80
• Manufacturer: MICROCHIP [Microchip Technology]

25.0
The comparator voltage reference is a 32-tap resistor
ladder network that provides a selectable reference
voltage. Although its primary purpose is to provide a
reference for the analog comparators, it may also be
used independently of them.
A block diagram of the module is shown in
The resistor ladder is segmented to provide a range of
CV
conserve power when the reference is not being used.
The module’s supply reference can be provided from
either device V
25.1
The comparator voltage reference module is controlled
through the CVRCON register
comparator voltage reference provides a range of
output voltage with 32 levels.
The CVR<4:0> selection bits (CVRCON<4:0>) offer a
range of output voltages.
the comparator voltage reference is computed.
REGISTER 25-1:
 2011 Microchip Technology Inc.
bit 7
Legend:
R = Readable bit
-n = Value at POR
bit 7
bit 6
bit 5
bit 4-0
REF
CVREN
R/W-0
values and has a power-down function to
COMPARATOR VOLTAGE
REFERENCE MODULE
Configuring the Comparator
Voltage Reference
DD
CVREN: Comparator Voltage Reference Enable bit
1 = CV
0 = CV
CVROE: Comparator V
1 = CV
0 = CV
CVRSS: Comparator V
1 = Comparator reference source, CV
0 = Comparator reference source, CV
CVR<4:0>: Comparator V
When CVRSS = 1 :
CV
When CVRSS = 0 :
CV
/V
CVROE
REF
REF
R/W-0
SS
or an external voltage reference.
CVRCON: COMPARATOR VOLTAGE REFERENCE CONTROL REGISTER
= (V
= (AV
REF
REF
REF
REF
Equation 25-1
REF
circuit powered on
circuit powered down
voltage level is output on CV
voltage level is disconnected from CV
SS
W = Writable bit
‘1’ = Bit is set
-) + (CVR<4:0>/32)  (V
) + (CVR<4:0>/32)  (AV
CVRSS
(Register
R/W-0
REF
REF
shows the how
REF
Figure
Source Selection bit
Output Enable bit
25-1). The
Value Selection 0  CVR<4:0>  31 bits
R/W-0
CVR4
25-1.
Preliminary
RSRC
RSRC
REF
DD
REF
+ – V
– AV
= V
= AV
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
pin
PIC18F66K80 FAMILY
REF
R/W-0
CVR3
REF
SS
EQUATION 25-1:
The comparator reference supply voltage can come
from either V
V
voltage source is selected by the CVRSS bit
(CVRCON<5>).
The settling time of the comparator voltage reference
must be considered when changing the CV
output (see
Characteristics”
DD
REF
REF
)
+ – V
If CVRSS = 1 :
CV
If CVRSS = 0 :
CV
-)
– AV
- that are multiplexed with RA3 and RA2. The
pin
REF
REF
REF
SS
= V
= AV
-
(
(
Table 31-2
DD
R/W-0
CVR2
REF
SS
and V
).
- +
+
CVR<4:0>
CVR<4:0>
SS
32
32
in
, or the external V
x = Bit is unknown
Section 31.0 “Electrical
R/W-0
CVR1
)
)
• (V
• (AV
DS39977C-page 385
REF
DD
+ – V
– AV
R/W-0
CVR0
REF
REF
SS
+ and
)
-)
bit 0
REF