AD7321 Analog Devices, AD7321 Datasheet - Page 20

• Manufacturer Part Number: AD7321
• Description: 500 kSPS, 2-Channel, Software-Selectable, True Bipolar Input, 12-Bit Plus Sign ADC
• Manufacturer: Analog Devices

Specifications of AD7321

• Resolution (bits): 13bit
• # Chan: 2
• Sample Rate: 500kSPS
• Interface: Ser,SPI
• Analog Input Type: Diff-Uni,SE-Uni
• Ain Range: Bip 10V,Bip 2.5V,Bip 5.0V,Uni 10V
• Adc Architecture: SAR
• Pkg Type: SOP

AD7321
Figure 37. Common-Mode Range for V
Figure 35. Common-Mode Range for V
Figure 36. Common-Mode Range for V
–1
–2
–3
–4
–5
–6
–2
–4
–2
–4
–6
–8
5
4
3
2
1
0
8
6
4
2
0
6
4
2
0
V
V
V
V
V
V
CC
REF
CC
REF
CC
REF
= 3V
= 5V
= 3V
= 3V
= 3V
= 2.5V
RANGE
RANGE
RANGE
±10V
±10V
±10V
±16.5V V
±16.5V V
±16.5V V
±5V RANGE
±5V RANGE
±5V RANGE
DD
DD
DD
/V
/V
/V
RANGE
RANGE
RANGE
±2.5V
±2.5V
SS
SS
±2.5V
SS
CC
CC
CC
= 3 V and REFIN/OUT = 2.5 V
RANGE
RANGE
= 3 V and REFIN/OUT = 3 V
RANGE
= 5 V and REFIN/OUT = 3 V
±12V V
±12V V
±12V V
±10V
±10V
±10V
±5V RANGE
±5V RANGE
±5V RANGE
DD
DD
DD
/V
/V
/V
SS
SS
SS
RANGE
RANGE
RANGE
±2.5V
±2.5V
±2.5V
Rev. A | Page 20 of 36
Pseudo Differential Inputs
The AD7321 can have one pseudo differential pair. The V
inputs are coupled to the signal source and must have an amplitude
within the selected range for that channel as programmed in the
range register. A dc input is applied to the V
applied to this input provides an offset for the V
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.
Figure 40 and Figure 41 show the typical voltage range on the
V
in the pseudo differential mode.
For example, when the AD7321 is configured to operate in
pseudo differential mode and the ±5 V range is selected with
±16.5 V V
pin can vary from −6.5 V to +6.5 V.
IN
Figure 38. Common-Mode Range for V
− pin for the different analog input ranges when configured
–2
–4
–6
–8
8
6
4
2
0
DD
V
V
/V
CC
REF
1
= 5V
SS
ADDITIONAL PINS OMITTED FOR CLARITY.
= 2.5V
Figure 39. Pseudo Differential Inputs
supplies and 5 V V
RANGE
±10V
V+
V–
±16.5V V
±5V RANGE
DD
/V
V
V
RANGE
SS
±2.5V
IN
IN
+
–
AD7321
CC
CC
= 5 V and REFIN/OUT = 2.5 V
, the voltage on the V
RANGE
±12V V
±10V
V
V
DD
SS
1
±5V RANGE
DD
V
IN
5V
CC
/V
− pin. The voltage
SS
IN
+ input from
RANGE
±2.5V
IN
IN
+
−