PIC16F631/677/685/687/689/690
FIGURE 9-4:
ANALOG INPUT MODEL
VDD
VT = 0.6V
Sampling
Switch
ANx
SS
RIC ≤ 1k
Rss
Rs
CPIN
5 pF
VA
I LEAKAGE
± 500 nA
CHOLD = 10 pF
VSS/VREF-
VT = 0.6V
6V
5V
RSS
VDD 4V
3V
Legend: CPIN
= Input Capacitance
= Threshold Voltage
VT
2V
I LEAKAGE = Leakage current at the pin due to
various junctions
RIC
SS
CHOLD
= Interconnect Resistance
= Sampling Switch
= Sample/Hold Capacitance
5 6 7 8 9 1011
Sampling Switch
(kΩ)
FIGURE 9-5:
ADC TRANSFER FUNCTION
Full-Scale Range
3FFh
3FEh
3FDh
3FCh
3FBh
1 LSB ideal
Full-Scale
Transition
004h
003h
002h
001h
000h
Analog Input Voltage
1 LSB ideal
Zero-Scale
Transition
VDD/VREF+
VSS/VREF-
© 2007 Microchip Technology Inc.
DS41262D-page 117
MICROCHIP [ MICROCHIP ]
