PIC18F4580T-I/PT Microchip Technology, PIC18F4580T-I/PT Datasheet - Page 269

• Manufacturer Part Number: PIC18F4580T-I/PT
• Description: IC PIC MCU FLASH 16KX16 44TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F4580T-I/PT

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: CAN, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 36
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 1.5K x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 11x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

22.0
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 is of the module shown in
Figure 22-1.The resistor ladder is segmented to
provide two ranges of CV
power-down function to conserve power when the
reference is not being used. The module’s supply
reference can be provided from either device V
or an external voltage reference.
22.1
The voltage reference module is controlled through the
CVRCON register (Register 22-1). The comparator
voltage reference provides two ranges of output voltage,
REGISTER 22-1:
© 2009 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
COMPARATOR VOLTAGE
REFERENCE MODULE
Configuring the Comparator
Voltage Reference
CVROE overrides the TRISA<0> bit setting. If enabled for output, RA2 must also be configured as an
input by setting TRISA<2> to ‘1’.
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
CVR<3:0>: Comparator V
When CVRR = 1:
CV
When CVRR = 0:
CV
CVROE
REF
REF
R/W-0
CVRCON: COMPARATOR VOLTAGE REFERENCE CONTROL REGISTER
= ((CVR<3:0>)/24) • (CV
= (CV
REF
REF
REF
REF
(1)
circuit powered on
circuit powered down
voltage level is also output on the RA0/AN0/CV
voltage is disconnected from the RA0/AN0/CV
RSRC
RSRC
REF
RSRC
W = Writable bit
‘1’ = Bit is set
values and has a
to 0.75 CV
to 0.75 CV
R/W-0
CVRR
/4) + ((CVR<3:0>)/32) • (CV
REF
REF
REF
Range Selection bit
REF
Source Selection bit
Output Enable bit
RSRC
RSRC
PIC18F2480/2580/4480/4580
Value Selection bits (0 ≤ (CVR<3:0>) ≤ 15)
DD
CVRSS
RSRC
R/W-0
/V
, with CV
, with CV
SS
)
RSRC
RSRC
RSRC
RSRC
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
= (V
= V
(1)
R/W-0
RSRC
CVR3
each with 16 distinct levels. 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
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
(see
Characteristics”).
/24 step size
/32 step size
DD
REF
REF
– V
If CVRR = 1:
CV
If CVRR = 0:
CV
CV
)
- that are multiplexed with RA2 and RA3. The
+) – (V
SS
REF
REF
RSRC
Table 28-3
REF
= ((CVR<3:0>)/24) x CV
REF
REF
= (CV
)
DD
R/W-0
CVR2
pin
-)
pin
and V
DD
REF
in
x 1/4) + (((CVR<3:0>)/32) x
Selection bits (CVR<3:0>), with
SS
, or the external V
x = Bit is unknown
Section 28.0
R/W-0
CVR1
DS39637D-page 269
RSRC
“Electrical
REF
R/W-0
CVR0
REF
output
+ and
bit 0