
2010-2012 Microchip Technology Inc.
DS41414D-page 173
PIC16(L)F1946/47
FIGURE 16-4:
ANALOG INPUT MODEL
FIGURE 16-5:
ADC TRANSFER FUNCTION
Note 1:
The reference voltage (VREF) has no effect on the equation, since it cancels itself out.
2:
The charge holding capacitor (CHOLD) is not discharged after each conversion.
3:
The maximum recommended impedance for analog sources is 10 k
. This is required to meet the pin
leakage specification.
CPIN
VA
Rs
Analog
5 pF
VDD
VT
0.6V
VT
0.6V
I LEAKAGE(1)
RIC
1k
Sampling
Switch
SS Rss
CHOLD = 10 pF
VSS/VREF-
6V
Sampling Switch
5V
4V
3V
2V
567 8 9 10 11
(k
)
VDD
Legend:
CPIN
VT
I LEAKAGE
RIC
SS
CHOLD
= Input Capacitance
= Threshold Voltage
= Leakage current at the pin due to
= Interconnect Resistance
= Sampling Switch
= Sample/Hold Capacitance
various junctions
RSS
.
RSS
= Resistance of Sampling Switch
Input
pin
3FFh
3FEh
ADC
O
u
tput
Code
3FDh
3FCh
03h
02h
01h
00h
Full-Scale
3FBh
0.5 LSB
VREF-
Zero-Scale
Transition
VREF+
Transition
1.5 LSB
Full-Scale Range
Analog Input Voltage