PIC18F2221-E/SS Microchip Technology, PIC18F2221-E/SS Datasheet - Page 249
![no-image](/images/manufacturer_photos/0/4/439/microchip_technology_sml.jpg)
PIC18F2221-E/SS
Manufacturer Part Number
PIC18F2221-E/SS
Description
4KB, Flash, 512bytes-RAM, 25I/O, 8-bit Family,nanoWatt 28 SSOP .209in TUBE
Manufacturer
Microchip Technology
Series
PIC® 18Fr
Datasheets
1.PIC18F2221-ISO.pdf
(402 pages)
2.PIC18F2221-ISO.pdf
(8 pages)
3.PIC18F2221-ISO.pdf
(30 pages)
4.PIC18F2221-ISO.pdf
(46 pages)
Specifications of PIC18F2221-E/SS
Core Processor
PIC
Core Size
8-Bit
Speed
40MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, HLVD, POR, PWM, WDT
Number Of I /o
25
Program Memory Size
4KB (2K x 16)
Program Memory Type
FLASH
Eeprom Size
256 x 8
Ram Size
512 x 8
Voltage - Supply (vcc/vdd)
4.2 V ~ 5.5 V
Data Converters
A/D 10x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 125°C
Package / Case
28-SSOP
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
- PIC18F2221-ISO PDF datasheet
- PIC18F2221-ISO PDF datasheet #2
- PIC18F2221-ISO PDF datasheet #3
- PIC18F2221-ISO PDF datasheet #4
- Current page: 249 of 402
- Download datasheet (7Mb)
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 of the module is shown in Figure 22-1.
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 device V
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, each with 16 distinct levels. The range to be
REGISTER 22-1:
© 2009 Microchip Technology Inc.
REF
COMPARATOR VOLTAGE
REFERENCE MODULE
Configuring the Comparator
Voltage Reference
values and has a power-down function to
bit 7
bit 6
bit 5
bit 4
bit 3-0
DD
/V
SS
or an external voltage reference.
CVRCON: COMPARATOR VOLTAGE REFERENCE CONTROL REGISTER
PIC18F2221/2321/4221/4321 FAMILY
Legend:
R = Readable bit
-n = Value at POR
bit 7
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
CVREN
R/W-0
Note 1: CVROE overrides the TRISA<2> bit setting.
REF
REF
= ((CVR<3:0>)/24) • (CV
= (CV
REF
REF
REF
REF
CVROE
circuit powered on
circuit powered down
voltage level is also output on the RA2/AN2/V
voltage is disconnected from the RA2/AN2/V
RSRC
RSRC
RSRC
R/W-0
/4) + ((CVR<3:0>)/32) • (CV
to 0.667 CV
to 0.75 CV
(1)
REF
REF
REF
R/W-0
CVRR
Range Selection bit
REF
Source Selection bit
Output Enable bit
W = Writable bit
‘1’ = Bit is set
RSRC
RSRC
Value Selection bits (0 ≤ (CVR<3:0>) ≤ 15)
RSRC
, with CV
, with CV
CVRSS
)
R/W-0
RSRC
RSRC
used is selected by the CVRR bit (CVRCON<5>). The
primary difference between the ranges is the size of the
steps
(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
Characteristics”).
output (see Table 27-3 in Section 27.0 “Electrical
REF
RSRC
If CVRR = 1:
CV
If CVRR = 0:
CV
CV
= (V
= V
- that are multiplexed with RA2 and RA3. The
RSRC
(1)
RSRC
REF
REF
RSRC
selected
DD
/32 step size (high range)
REF
R/W-0
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
CVR3
/24 step size (low range)
– V
= ((CVR<3:0>)/24) x CV
= (CV
)
+) – (V
)
DD
SS
REF
and V
RSRC
REF
by
REF
-/CV
R/W-0
-/CV
CVR2
-)
SS
x 1/4) + (((CVR<3:0>)/32) x
the
REF
, or the external V
REF
pin
CV
pin
x = Bit is unknown
REF
R/W-0
CVR1
DS39689F-page 249
RSRC
selection
REF
R/W-0
CVR0
+ and
bit 0
REF
bits
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