AD73322AR Analog Devices Inc, AD73322AR Datasheet - Page 31

• Manufacturer Part Number: AD73322AR
• Description: IC ANALOG FRONT END DUAL 28-SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD73322AR

• Rohs Status: RoHS non-compliant
• Number Of Bits: 16
• Number Of Channels: 4
• Power (watts): 73mW
• Voltage - Supply, Analog: 2.7 V ~ 5.5 V
• Voltage - Supply, Digital: 2.7 V ~ 5.5 V
• Package / Case: 28-SOIC (7.5mm Width)
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 3.3V
• Package Type: SOIC W
• Lead Free Status / RoHS Status: Not Compliant

The AD73322’s ADC inputs are biased about the internal refer-
ence level (REFCAP level), therefore it may be necessary to
bias external signals to this level using the buffered REFOUT
level as the reference. This is applicable in either dc- or ac-
coupled configurations. In the case of dc coupling, the signal
(biased to REFOUT) may be applied directly to the inputs
(using amplifier bypass), as shown in Figure 28, or it may be
conditioned in an external op amp where it can also be biased
to the reference level using the buffered REFOUT signal as
shown in Figure 29 or it is possible to connect inputs directly
to the AD73322’s input op amps as shown in Figure 30.
In the case of ac coupling, a capacitor is used to couple the
signal to the input of the ADC. The ADC input must be biased
to the internal reference (REFCAP) level which is done by
connecting the input to the REFOUT pin through a 10 k
resistor as shown in Figure 31.
REV. B
Figure 30. Analog Input (DC-Coupled) Using Internal
Amplifiers
0.1 F
0.1 F
10k
Figure 31. Analog Input (AC-Coupled) Differential
10k
50k
50k
100
100
100pF
100pF
0.047
0.047
50k
50k
F
F
0.1 F
0.1 F
VOUTP1
VOUTN1
REFOUT
VOUTP1
VOUTN1
REFOUT
REFCAP
REFCAP
VFBN1
VFBP1
VFBN1
VFBP1
VINN1
VINN1
VINP1
VINP1
V
V
REF
REF
+6/–15dB
+6/–15dB
PGA
PGA
REFERENCE
REFERENCE
GAIN
GAIN
1
1
CONTINUOUS
CONTINUOUS
LOW-PASS
LOW-PASS
FILTER
FILTER
TIME
TIME
AD73322
AD73322
V
V
REF
REF
0/38dB
0/38dB
PGA
PGA
–31–
If the ADC is being connected in single-ended mode, the
AD73322 should be programmed for single-ended mode using
the SEEN and INV bits of CRF and the inputs connected as
shown in Figure 32. When operated in single-ended input
mode, the AD73322 can multiplex one of the two inputs to the
ADC input.
If best performance is required from a single-ended source, it
is possible to configure the AD73322’s input amplifiers as a
single-ended to differential converter as shown in Figure 33.
Figure 33. Single-Ended to Differential Conversion On
Analog Input
Figure 32. Analog Input (AC-Coupled) Single-Ended
0.1 F
10k
50k
50k
100
0.047
100pF
100pF
50k
50k
F
0.1 F
REFOUT
VOUTP1
VOUTN1
REFCAP
REFOUT
0.1 F
VOUTP1
VOUTN1
REFCAP
VFBN1
VFBP1
VINN1
VINP1
VFBN1
VFBP1
VINN1
VINP1
V
REF
V
REF
+6/–15dB
+6/–15dB
PGA
PGA
REFERENCE
REFERENCE
GAIN
GAIN
1
CONTINUOUS
1
LOW-PASS
CONTINUOUS
FILTER
LOW-PASS
TIME
FILTER
TIME
AD73322
AD73322
AD73322
V
REF
V
REF
0/38dB
PGA
0/38dB
PGA