
REV. A
AD7866
–13–
CS
SCLK
RANGE
D
OUT
A
D
OUT
B
1816 161
AB
V
REF
/2 ⴞ V
REF
/2
INPUT RANGE
TWOS COMPLEMENT
Figure 7. Selecting V
REF
/2
±
V
REF
/2 Input Range with Twos Complement Output Coding
CS
SCLK
RANGE
D
OUT
A
D
OUT
B
1816 161
AB
0V TO 2 ⴛ V
REF
INPUT RANGE
STRAIGHT BINARY
Figure 8. Selecting 0 V to 2
V
REF
Input Range with Straight Binary Output Coding
REF SELECT
V
REF
AD7866
D
OUT
D
CAP
A
D
CAP
B
V
DRIVE
V
IN
470nF
470nF
100nF
V
REF
R4
R3
R2
V
R1
V
0V
TWOS
COMPLEMENT
011
111
+V
REF
V
REF
–V
REF
(= 2 ⴛ V
REF
)
000
000
100
000
(= 0V)
R1 = R2 = R3 = R4
V
DD
V
DD
DSP/P
Figure 9. Handling Bipolar Signals with the AD7866
000...000
0V
ANALOG INPUT
111...111
000...001
000...010
111...110
111...000
011...111
1LSB
V
REF
– 1LSB
1LSB = V
REF
/4096
ADC CODE
Figure 10. Straight Binary Transfer
Characteristic with 0 V to V
REF
Input Range
100...000
ANALOG INPUT
011...110
100...001
100...010
000...001
111...111
1LSB = 2 ⴛ V
REF
/4096
ADC CODE
011...111
000...000
+V
REF
– 1LSB–V
REF
+ 1LSB
V
REF
– 1LSB
Figure 11. Twos Complement Transfer
Characteristic with V
REF
±
V
REF
Input Range
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