PIC16F88-I/SO Microchip Technology Inc., PIC16F88-I/SO Datasheet - Page 129

• Manufacturer Part Number: PIC16F88-I/SO
• Description: 18 PIN, 7 KB FLASH, 368 RAM, 16 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F88-I/SO

• A/d Inputs: 7-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 16
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 18-pin SOIC
• Programmable Memory: 7K Bytes
• Ram Size: 368 Bytes
• Speed: 20 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

14.0
The comparator voltage reference generator is a 16-tap
resistor ladder network that provides a fixed voltage
reference when the comparators are in mode ‘010’. A
programmable register controls the function of the refer-
ence generator. Register 14-1 lists the bit functions of
the CVRCON register.
As shown in Figure 14-1, the resistor ladder is seg-
mented to provide two ranges of CV
a power-down function to conserve power when the
reference is not being used. The comparator reference
REGISTER 14-1:
 2005 Microchip Technology Inc.
COMPARATOR VOLTAGE
REFERENCE MODULE
bit 7
bit 6
bit 5
bit 4
bit 3-0
CVRCON: COMPARATOR VOLTAGE REFERENCE CONTROL REGISTER
(ADDRESS 9Dh)
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
Unimplemented: Read as ‘0’
CVR<3:0>: Comparator V
When CVRR = 1:
CV
When CVRR = 0:
CV
CVREN
R/W-0
Note 1: V
REF
REF
REF
REF
REF
REF
= (VR<3:0>/24) (CV
= 1/4 (CV
circuit powered on
circuit powered down
voltage level is output on the RA2/AN2/CV
voltage level is disconnected from the RA2/AN2/CV
RSRC
RSRC
REF
REF
CVROE
R/W-0
values and has
is available on the PIC16F88 device only.
to 0.625 CV
to 0.72 CV
RSRC
REF
REF
) + (VR3:VR0/32) (CV
Range Selection bit
REF
R/W-0
CVRR
Output Enable bit
RSRC
W = Writable bit
‘1’ = Bit is set
RSRC
RSRC
Value Selection 0
with CV
)
with CV
supply voltage (also referred to as CV
directly from V
voltage at the top of the ladder is CV
where V
switch transistor. This reference will only be as
accurate as the values of CV
The output of the reference generator may be
connected to the RA2/AN2/CV
available on the PIC16F88 device only). This can be
used as a simple D/A function by the user if a very high-
impedance load is used. The primary purpose of this
function is to provide a test path for testing the
reference generator function.
U-0
RSRC
—
RSRC
(1)
/32 step size
RSRC
/24 step size
SAT
VR3:VR0
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
R/W-0
CVR3
)
REF
is the saturation voltage of the power
DD
/V
. It should be noted, however, that the
REF
15 bits
PIC16F87/88
REF
- pin
R/W-0
CVR2
/V
(1)
REF
(1)
RSRC
REF
- pin
x = Bit is unknown
R/W-0
CVR1
/V
and V
DS30487C-page 127
(1)
REF
RSRC
- pin (V
SAT
RSRC
.
R/W-0
CVR0
) comes
– V
REF
bit 0
SAT
- is
,