PCM18XK1 Microchip Technology, PCM18XK1 Datasheet - Page 267

• Manufacturer Part Number: PCM18XK1
• Description: MODULE PROC PIC18F8680,6680,8565
• Manufacturer: Microchip Technology

Specifications of PCM18XK1

• Accessory Type: Processor Module
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: ICE2000
• For Use With: ICE2000 - EMULATOR MPLAB-ICE 2000 POD
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

21.0
The comparator voltage reference is a 16-tap resistor
ladder network that provides a selectable voltage
reference. The resistor ladder is segmented to provide
two ranges of CV
function to conserve power when the reference is not
being used. The CVRCON register controls the
operation of the reference as shown in Register 21-1.
The block diagram is given in Figure 21-1.
The comparator reference supply voltage can come
from either V
V
comparator reference supply voltage is controlled by
the CVRSS bit.
REGISTER 21-1:
 2004 Microchip Technology Inc.
REF
- that are multiplexed with RA3 and RA2. The
COMPARATOR VOLTAGE
REFERENCE MODULE
bit 7
bit 6
bit 5
bit 4
bit 3-0
DD
or V
REF
SS
values and has a power-down
CVRCON REGISTER
bit 7
Legend:
R = Readable bit
- n = Value at POR
CVREN: Comparator Voltage Reference Enable bit
1 = CV
0 = CV
CVROE: Comparator V
1 = CV
0 = CV
CVRR: Comparator V
1 = 0.00 CV
0 = 0.25 CV
CVRSS: Comparator V
1 = Comparator reference source, CV
0 = Comparator reference source, CV
CVR3:CVR0: Comparator V
When CVRR = 1:
CV
When CVRR = 0:
CV
, or the external V
CVREN
R/W-0
Note:
Note 1: If enabled for output, RF5 must also be configured as an input by setting TRISF<5>
REF
REF
= (CVR<3:0>/24) (CV
= 1/4 (CV
REF
REF
REF
REF
circuit powered on
circuit powered down
voltage level is also output on the RF5/AN10/C1IN+/CV
voltage is disconnected from the RF5/AN10/C1IN+/CV
To select (V
reference configuration bits in the ADCON1 register (ADCON1<5:4>) must also be
set to ‘11’.
to ‘1’.
RSRC
RSRC
CVROE
R/W-0
to 0.625 CV
to 0.71875 CV
RSRC
REF
PIC18F6585/8585/6680/8680
REF
REF
REF
REF
) + (CVR3:CVR0/32) (CV
+ and
R/W-0
CVRR
Range Selection bit
+ – V
Source Selection bit
Output Enable bit
W = Writable bit
‘1’ = Bit is set
REF
RSRC
RSRC
REF
Value Selection bits (0
RSRC
-) as the comparator voltage reference source, the voltage
)
with CV
CVRSS
R/W-0
RSRC
RSRC
with CV
21.1
The comparator voltage reference can output 16 distinct
voltage levels for each range. The equations used to
calculate the output of the comparator voltage reference
are as follows:
The settling time of the comparator voltage reference
must be considered when changing the CV
(Section 27.0 “Electrical Characteristics”).
RSRC
If CVRR = 1:
CV
If CVRR = 0:
CV
= V
= V
(1)
RSRC
REF
REF
REF
DD
Configuring the Comparator
Voltage Reference
/24 step size
R/W-0
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
CVR3
RSRC
– V
= (CVR<3:0>/24) x CV
= (CV
+ – V
/32 step size
SS
)
REF
DD
VR3:VR0
x 1/4) + (CVR<3:0>/32) x CV
-
R/W-0
CVR2
REF
REF
15)
pin
pin
x = Bit is unknown
R/W-0
CVR1
RSRC
DS30491C-page 265
REF
R/W-0
CVR0
output
RSRC
bit 0