AD73422BB-80 Analog Devices Inc, AD73422BB-80 Datasheet - Page 34

• Manufacturer Part Number: AD73422BB-80
• Manufacturer: Analog Devices Inc

Specifications of AD73422BB-80

• Single Supply Voltage (typ): 3.3V
• Single Supply Voltage (min): 3V
• Single Supply Voltage (max): 3.6V
• Package Type: BGA
• Lead Free Status / RoHS Status: Not Compliant

AD73422
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 28.
If the ADC is being connected in single-ended mode, the
AD73422 should be programmed for single-ended mode using
the SEEN and INV bits of CRF and the inputs connected as
shown in Figure 29. When operated in single-ended input
mode, the AD73422 can multiplex one of the two inputs to the
ADC input.
0.1 F
0.1 F
10k
10k
0.1 F
Figure 29. Analog Input (AC-Coupled) Single-Ended
Figure 28. Analog Input (AC-Coupled) Differential
10k
0.047 F
100
0.047 F
0.047 F
REFOUT
VOUTN1
VOUTP1
REFCAP
100
100
REFOUT
VOUTN1
REFCAP
VOUTP1
0.1 F
0.1 F
VFBN1
VINN1
VINP1
VFBP1
V
VFBN1
VINN1
VINP1
VFBP1
V
REF
REF
+6/–15dB
+6/–15dB
GAIN
PGA
GAIN
PGA
1
1
REFERENCE
REFERENCE
CONTINUOUS
CONTINUOUS
LOW-PASS
LOW-PASS
FILTER
TIME
FILTER
TIME
AD73422
AD73422
V
V
REF
REF
0/38dB
PGA
0/38dB
PGA
–34–
If best performance is required from a single-ended source, it is
possible to configure the AD73422’s input amplifiers as a
single-ended-to-differential converter as shown in Figure 30.
Interfacing to an Electret Microphone
Figure 31 details an interface for an electret microphone which
may be used in some voice applications. Electret microphones
typically feature a FET amplifier whose output is accessed on
the same lead that supplies power to the microphone, therefore
this output signal must be capacitively coupled to remove the
power supply (dc) component. In this circuit the AD73422
10 F
Figure 30. Single-Ended-to-Differential Conversion On
Analog Input
+5V
50k
R
Figure 31. Electret Microphone Interface Circuit
R
A
B
C2
100pF
50k
100pF
50k
50k
ELECTRET
PROBE
REFOUT
VOUTN1
REFCAP
VOUTP1
R1
REFOUT
VOUTN1
REFCAP
0.1 F
VOUTP1
C
REFCAP
C1
R2
VFBN1
VINN1
VINP1
VFBP1
V
REF
VFBN1
VINN1
VINP1
VFBP1
V
REF
+6/–15dB
GAIN
PGA
+6/–15dB
GAIN
1
PGA
1
REFERENCE
CONTINUOUS
REFERENCE
LOW-PASS
CONTINUOUS
FILTER
LOW-PASS
TIME
FILTER
TIME
AD73422
AD73422
V
REF
V
0/38dB
REF
PGA
0/38dB
PGA
REV. 0