Datasheet
Data Sheet AD7328
Rev. C | Page 19 of 36
04852-045
±16.5V V
DD
/V
SS
±12V V
DD
/V
SS
5
–6
V
COM
RANGE (V)
4
3
2
1
0
–1
–2
–3
–4
–5
V
CC
=3V
V
REF
=3V
±2.5V
RANGE
±10V
RANGE
±5V RANGE
±2.5V
RANGE
±5V RANGE
±10V
RANGE
Figure 35. Common-Mode Range for V
CC
= 3 V and REFIN/OUT = 3 V
04852-046
±16.5V V
DD
/V
SS
±12V V
DD
/V
SS
V
COM
RANGE (V)
V
CC
=5V
V
REF
=3V
8
–4
6
4
2
0
–2
±2.5V
RANGE
±10V
RANGE
±5V RANGE
±2.5V
RANGE
±5V RANGE
±10V
RANGE
Figure 36. Common-Mode Range for V
CC
= 5 V and REFIN/OUT = 3 V
6
–8
4
2
0
–2
–4
–6
04852-047
±16.5V V
DD
/V
SS
±12V V
DD
/V
SS
V
COM
RANGE (V)
V
CC
=3V
V
REF
=2.5V
±2.5V
RANGE
±10V
RANGE
±5V RANGE
±2.5V
RANGE
±5V RANGE
±10V
RANGE
Figure 37. Common-Mode Range for V
CC
= 3 V and REFIN/OUT = 2.5 V
8
–8
6
4
2
0
–2
–4
–6
04852-048
±16.5V V
DD
/V
SS
±12V V
DD
/V
SS
V
COM
RANGE (V)
V
CC
=5V
V
REF
=2.5V
±2.5V
RANGE
±10V
RANGE
±5V RANGE
±2.5V
RANGE
±5V RANGE
±10V
RANGE
Figure 38. Common-Mode Range for V
CC
= 5 V and REFIN/OUT = 2.5 V
Pseudo Differential Inputs
The AD7328 can have four pseudo differential pairs or seven
pseudo differential inputs referenced to a common V
IN
− pin. e
V
IN
+ inputs are coupled to the signal source and must have an
amplitude within the selected range for that channel as program-
med in the range register. A dc input is applied to the V
IN
− pin.
The voltage applied to this input provides an offset for the
V
IN
+ input from ground or a pseudo ground. Pseudo differential
inputs separate the analog input signal ground from the ADC
ground, allowing cancellation of dc common-mode voltages.
Figure 39 shows the configuration of the AD7328 in pseudo
differential mode.
When a conversion takes place, the pseudo differential ground
corresponds to Code −4096, and the maximum amplitude
corresponds to Code +4095.
AD7328
1
V
IN
+
V+
V–
V
DD
V
SS
V
CC
5V
1
ADDITIONAL PINS OMITTED FOR CLARITY.
V
IN
–
04852-028
Figure 39. Pseudo Differential Inputs
Figure 40 and Figure 41 show the typical voltage range on the
V
IN
− pin for various analog input ranges when congured in
the pseudo differential mode.
For example, when the AD7328 is configured to operate in
pseudo differential mode and the ±5 V range is selected with
±16.5 V V
DD
/V
SS
supplies and 5 V V
CC
, the voltage on the
V
IN
− pin can vary from −6.5 V to +6.5 V.