
1997 Microchip Technology Inc.
DS30272A-page 45
PIC16C71X
7.9
Transfer Function
The ideal transfer function of the A/D converter is as fol-
lows: the rst transition occurs when the analog input
7.10
References
A very good reference for understanding A/D convert-
ers is the "Analog-Digital Conversion Handbook" third
edition, published by Prentice Hall (ISBN 0-13-03-
2848-0).
FIGURE 7-6:
A/D TRANSFER FUNCTION
Digital
code
output
FFh
FEh
04h
03h
02h
01h
00h
0.5
LSb
1
LSb
2
LSb
3
LSb
4
LSb
255
LSb
256
LSb
(full
scale)
Analog input voltage
FIGURE 7-7:
FLOWCHART OF A/D OPERATION
Acquire
ADON = 0
ADON = 0?
GO = 0?
A/D Clock
GO = 0
ADIF = 0
Abort Conversion
SLEEP
Power-down A/D
Wait 2 TAD
Wake-up
Yes
No
Yes
No
Yes
Finish Conversion
GO = 0
ADIF = 1
Device in
No
Yes
Finish Conversion
GO = 0
ADIF = 1
Wait 2 TAD
Stay in Sleep
Selected Channel
= RC?
SLEEP
No
Yes
Instruction?
Start of A/D
Conversion Delayed
1 Instruction Cycle
From Sleep?
Power-down A/D
Yes
No
Wait 2 TAD
Finish Conversion
GO = 0
ADIF = 1
SLEEP?