PIC16F72 Datasheet, PDF (57/136 Pages) Microchip Technology – 28-Pin, 8-Bit CMOS FLASH MCU with A/D Converter

PIC16F72
FIGURE 10-1:
A/D BLOCK DIAGRAM
A/D
Converter
VAIN
(Input Voltage)
VDD
VREF
000 or
010 or
100
(Reference
Voltage)
001 or
011 or
101
PCFG2:PCFG0
CHS2:CHS0
100
011
010
001
000
RA5/AN4
RA3/AN3/VREF
RA2/AN2
RA1/AN1
RA0/AN0
FIGURE 10-2:
ANALOG INPUT MODEL
Rs ^ANx
VA
CPIN
5 pF
VDD
VT = 0.6 V
RIC ≤ 1 k
Sampling
Switch
SS _RSS
VT = 0.6 V
I leakage
± 500 nA
CHOLD
= DAC capacitance
= 51.2 pF
VSS
Legend: CPIN
= input capacitance
VT
= threshold voltage
I leakage = leakage current at the pin due to
various junctions
RIC
= interconnect resistance
SS
= sampling switch
CHOLD = sample/hold capacitance (from DAC)
6V
5V
VDD 4V
3V
2V
5 6 7 8 9 10 11
Sampling Switch
( kΩ )
 2002 Microchip Technology Inc.
DS39597B-page 55