AD7327
Rev. B | Page 20 of 36
±16.5V VDD/VSS
±12V VDD/VSS
5
–6
V
CO
M
R
ANG
E
(
V
)
4
3
2
1
0
–1
–2
–3
–4
–5
VCC =3V
VREF =3V
±2.5V
RANGE
±10V
RANGE
±5V RANGE
±2.5V
RANGE
±5V RANGE
±10V
RANGE
05
401-
045
Figure 35. Common-Mode Range for VCC = 3 V and REFIN/OUT = 3 V
±16.5V VDD/VSS
±12V VDD/VSS
V
CO
M
R
ANG
E
(
V
)
VCC =5V
VREF =3V
8
–4
6
4
2
0
–2
±2.5V
RANGE
±10V
RANGE
±5V RANGE
±2.5V
RANGE
±5V RANGE
±10V
RANGE
05
401-
046
Figure 36. Common-Mode Range for VCC = 5 V and REFIN/OUT = 3 V
6
–8
4
2
0
–2
–4
–6
±16.5V VDD/VSS
±12V VDD/VSS
V
CO
M
R
ANG
E
(
V
)
VCC =3V
VREF =2.5V
±2.5V
RANGE
±10V
RANGE
±5V RANGE
±2.5V
RANGE
±5V RANGE
±10V
RANGE
05
401-
047
Figure 37. Common-Mode Range for VCC = 3 V and REFIN/OUT = 2.5 V
8
–8
6
4
2
0
–2
–4
–6
±16.5V VDD/VSS
±12V VDD/VSS
V
CO
M
RANG
E
(
V
)
VCC =5V
VREF =2.5V
±2.5V
RANGE
±10V
RANGE
±5V RANGE
±2.5V
RANGE
±5V RANGE
±10V
RANGE
05
40
1-
0
48
Figure 38. Common-Mode Range for VCC = 5 V and REFIN/OUT = 2.5 V
Pseudo Differential Inputs
The
AD7327 can have four pseudo differential pairs or seven
pseudo differential inputs referenced to a common VIN pin.
The VIN+ inputs are coupled to the signal source and must have
an amplitude within the selected range for that channel as
programmed in the range registers. A dc input is applied to the
VIN pin. The voltage applied to this input provides an offset for
the VIN+ 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.
When a conversion takes place, the pseudo ground corresponds
to Code 4096 and the maximum amplitude corresponds to
Code +4095.
AD73271
VIN+
V+
V–
VDD
VSS
VCC
5V
1ADDITIONAL PINS OMITTED FOR CLARITY.
VIN–
05
40
1-
0
28
Figure 39. Pseudo Differential Inputs
VIN pin for the different analog input ranges when configured
in the pseudo differential mode.
For example, when th
e AD7327 is configured to operate in
pseudo differential mode and the ±5 V range is selected, with
±16.5 V VDD/VSS supplies and 5 V VCC, the voltage on the VIN
pin can vary from 6.5 V to +6.5 V.