PIC16F636-I Datasheet, PDF (86/234 Pages) Microchip Technology – 8/14-Pin, Flash-Based 8-Bit CMOS Microcontrollers with nanoWatt Technology

PIC12F635/PIC16F636/639
REGISTER 7-5: VRCON: VOLTAGE REFERENCE CONTROL REGISTER
R/W-0
VREN
bit 7
U-0
R/W-0
U-0
R/W-0
R/W-0
—
VRR
—
VR3
VR2
R/W-0
VR1
R/W-0
VR0
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
bit 6
bit 5
bit 4
bit 3-0
VREN: CVREF Enable bit
1 = CVREF circuit powered on
0 = CVREF circuit powered down, no IDD drain and CVREF = VSS.
Unimplemented: Read as ‘0’
VRR: CVREF Range Selection bit
1 = Low range
0 = High range
Unimplemented: Read as ‘0’
VR<3:0>: CVREF Value Selection bits (0 ≤ VR<3:0> ≤ 15)
When VRR = 1: CVREF = (VR<3:0>/24) * VDD
When VRR = 0: CVREF = VDD/4 + (VR<3:0>/32) * VDD
FIGURE 7-10:
COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM
16 Stages
VDD
VREN
CVREF to
Comparator
Input
8R
R
R
16-1 Analog
MUX
15
14
2
1
0
VR<3:0>⁽¹⁾
R
R
8R
VRR
VREN
VR<3:0> = 0000
VRR
Note 1:
Care should be taken to ensure VREF remains
within the comparator common mode input
range. See Section 15.0 “Electrical Specifica-
tions” for more detail.
DS41232D-page 84
© 2007 Microchip Technology Inc.