AD73322LAST Analog Devices Inc, AD73322LAST Datasheet - Page 33

• Manufacturer Part Number: AD73322LAST
• Description: IC ANALOG FRONT END DUAL 44-LQFP
• Manufacturer: Analog Devices Inc

Specifications of AD73322LAST

• 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: 44-LQFP

The AD73322L’s ADC inputs are biased about the internal
reference 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-coupled 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 33, 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 34, or it is possible to connect inputs directly to
the AD73322L’s input op amps as shown in Figure 35.
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 kΩ
resistor, as shown in Figure 36.
10kΩ
0.1µF
0.1µF
10kΩ
50kΩ
50kΩ
Figure 35. Analog Input (DC Coupled) Using Internal Amplifiers
100Ω
0.047µF
100Ω
0.047µF
100pF
50kΩ
50kΩ
100pF
0.1µF
0.1µF
Figure 36. Analog Input (AC-Coupled) Differential
VOUTP1
REFOUT
REFCAP
VOUTN1
VFBN1
VFBP1
VOUTP1
VOUTN1
REFOUT
REFCAP
VINN1
VINP1
VFBN1
VFBP1
VINN1
VINP1
V
REF
V
REF
+6/–15dB
+6/–15dB
PGA
REFERENCE
PGA
REFERENCE
GAIN
CONTINUOUS
±1
GAIN
LOW-PASS
CONTINUOUS
±1
FILTER
LOW-PASS
TIME
FILTER
TIME
AD73322L
V
REF
AD73322L
V
REF
0/38dB
PGA
0/38dB
PGA
Rev. A | Page 33 of 48
If the ADC is being connected in single-ended mode, the
AD73322L should be programmed for single-ended mode
using the SEEN and INV bits of CRF and the inputs connected
as shown in Figure 37. When operated in single-ended input
mode, the AD73322L 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 AD73322L’s input amplifiers as a
single-ended-to-differential converter, as shown in Figure 38.
0.1µF
50kΩ
50kΩ
10kΩ
Figure 38. Single-Ended-to-Differential Conversion on Analog Input
100Ω
0.047µF
100pF
100pF
50kΩ
50kΩ
0.1µF
0.1µF
Figure 37. Analog Input (AC-Coupled) Single-Ended
VOUTP1
VOUTN1
REFOUT
REFCAP
VFBN1
VFBP1
VOUTP1
VOUTN1
REFOUT
REFCAP
VINN1
VINP1
VFBN1
VFBP1
VINN1
VINP1
V
REF
V
REF
+6/–15dB
+6/–15dB
PGA
REFERENCE
PGA
REFERENCE
GAIN
CONTINUOUS
±1
GAIN
CONTINUOUS
LOW-PASS
±1
LOW-PASS
FILTER
TIME
FILTER
TIME
AD73322L
AD73322L
V
AD73322L
V
REF
REF
0/38dB
PGA
0/38dB
PGA