MA180025 Microchip Technology, MA180025 Datasheet - Page 305

• Manufacturer Part Number: MA180025
• Description: MODULE PLUG-IN PIC18F87J90 PIM
• Manufacturer: Microchip Technology
• Series: PIC®r

Specifications of MA180025

• Accessory Type: Plug-In Module (PIM) - PIC18F87J90
• Product: Microcontroller Modules
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC18
• Silicon Core Number: PIC18F
• Silicon Family Name: PIC18FxxJxx
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: PICDEM LCD 2 Demonstration Board (DM163030)
• For Use With: DM163030 - KIT DEV PICDEM LCD2
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

23.0
The comparator voltage reference is a 16-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 Figure 23-1.
The resistor ladder is segmented to provide two ranges
of CV
conserve power when the reference is not being used.
The module’s supply reference can be provided from
either the device V
reference.
23.1
The comparator voltage reference module is controlled
through the CVRCON register (Register 23-1). The
comparator voltage reference provides two ranges of
output voltage, each with 16 distinct levels.
REGISTER 23-1:
 2010 Microchip Technology Inc.
bit 7
Legend:
R = Readable bit
-n = Value at POR
bit 7
bit 6
bit 5
bit 4
bit 3-0
Note 1:
CVREN
R/W-0
REF
COMPARATOR VOLTAGE
REFERENCE MODULE
Configuring the Comparator
Voltage Reference
values and has a power-down function to
CVROE overrides the TRISF<5> bit setting.
CVREN: Comparator Voltage Reference Enable bit
1 = CV
0 = CV
CVROE: Comparator V
1 = CV
0 = CV
CVRR: Comparator V
1 = 0 to 0.667 CV
0 = 0.25 CV
CVRSS: Comparator V
1 = Comparator reference source, CV
0 = Comparator reference source, CV
CVR<3:0>: Comparator V
When CVRR = 1:
CV
When CVRR = 0:
CV
CVROE
REF
REF
R/W-0
DD
CVRCON: COMPARATOR VOLTAGE REFERENCE CONTROL REGISTER
= ((CVR<3:0>)/24)  (CV
= (CV
REF
REF
REF
REF
/V
(1)
SS
voltage is disconnected from the RF5/AN10/CV
circuit powered on
circuit powered down
voltage level is also output on the RF5/AN10/CV
RSRC
RSRC
or an external voltage
W = Writable bit
‘1’ = Bit is set
R/W-0
CVRR
/4) + ((CVR<3:0>)/32)  (CV
RSRC
to 0.75 CV
REF
REF
REF
, with CV
Range Selection bit
REF
Source Selection bit
Output Enable bit
RSRC
Value Selection bits (0  (CVR<3:0>)  15)
RSRC
CVRSS
RSRC
R/W-0
, with CV
)
/24 step size (low range)
RSRC
RSRC
RSRC
= (V
= V
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
(1)
PIC18F87J90 FAMILY
RSRC
R/W-0
DD
CVR3
The range to be used is selected by the CVRR bit
(CVRCON<5>). The primary difference between the
ranges is the size of the steps selected by the CV
Selection bits (CVR<3:0>), with one range offering finer
resolution. The equations used to calculate the output
of the comparator voltage reference are as follows:
The comparator reference supply voltage can come
from either V
V
voltage source is selected by the CVRSS bit
(CVRCON<4>).
The settling time of the comparator voltage reference
must be considered when changing the CV
output (see Table 28-3 in Section 28.0 “Electrical
Characteristics”).
/32 step size (high range)
REF
REF
– V
)
+) – (V
If CVRR = 1:
CV
If CVRR = 0:
CV
(CV
- that are multiplexed with RA2 and RA3. The
SS
REF
REF
RSRC
REF
REF
= ((CVR<3:0>)/24) x (CV
= (CV
REF
)
DD
-)
R/W-0
CVR2
/SEG23/C1INB pin
/SEG23/C1INB pin
and V
RSRC
/4) + ((CVR<3:0>)/32) x
SS
, or the external V
x = Bit is unknown
R/W-0
CVR1
DS39933D-page 305
RSRC
)
R/W-0
CVR0
REF
+ and
bit 0
REF
REF