AD73322LYR Analog Devices Inc, AD73322LYR Datasheet - Page 34
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AD73322LYR
Manufacturer Part Number
AD73322LYR
Description
IC ANALOG FRONT END DUAL 28-SOIC
Manufacturer
Analog Devices Inc
Datasheet
1.AD73322LARZ.pdf
(48 pages)
Specifications of AD73322LYR
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)
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
AD73322LYRZ
Manufacturer:
Analog Devices Inc
Quantity:
135
AD73322L
INTERFACING TO AN ELECTRET MICROPHONE
Figure 39 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 which supplies power to the microphone;
therefore, this output signal must be capacitively coupled to
remove the power supply (dc) component. In this circuit, the
AD73322L input channel is being used in single-ended mode
where the internal inverting amplifier provides suitable gain to
scale the input signal relative to the ADC’s full-scale input
range. The buffered internal reference level at REFOUT is used
via an external buffer to provide power to the electret
microphone. This provides a quiet, stable supply for the
microphone. If this is not a concern, then the microphone can
be powered from the system power supply.
ANALOG OUTPUT
The AD73322L’s differential analog output (VOUT) is produced
by an on-chip differential amplifier. The differential output can
be ac-coupled or dc-coupled directly to a load which can be a
headset or the input of an external amplifier (the specified
minimum resistive load on the output section is 150 Ω.) It is
possible to connect the outputs in either a differential or a
single-ended configuration, but please note that the effective
maximum output voltage swing (peak to peak) is halved in the
case of single-ended connection. Figure 40 shows a simple
circuit providing a differential output with ac coupling. The
capacitors in this circuit (C
can be chosen as follows:
where f
10µF
C
OUT
R
5V
A
R
B
C
=
= desired cutoff frequency.
C2
ELECTRICITY
PROBE
2
R1
π
Figure 39. Electret Microphone Interface Circuit
fc
100pF
50kΩ
1
R
LOAD
VOUTP1
REFOUT
REFCAP
VOUTN1
C
VFBN1
VFBP1
VINN1
VINP1
REFCAP
V
REF
OUT
) are optional; if used, their value
+6/–15dB
PGA
REFERENCE
GAIN
CONTINUOUS
±1
LOW-PASS
FILTER
TIME
AD73322L
V
REF
0/38dB
PGA
Rev. A | Page 34 of 48
Figure 41 shows an example circuit for providing a single-ended
output with ac coupling. The capacitor of this circuit (C
not optional if dc current drain is to be avoided.
R
R
LOAD
LOAD
Figure 41. Example Circuit for Single-Ended Output
Figure 40. Example Circuit for Differential Output
C
C
C
C
REFCAP
OUT
OUT
OUT
0.1µF
VOUTN1
REFOUT
REFCAP
VOUTN1
REFOUT
REFCAP
VOUTP1
VOUTP1
VFBN1
VFBP1
VFBN1
VFBP1
VINN1
VINN1
VINP1
VINP1
V
V
REF
REF
+6/–15dB
+6/–15dB
PGA
PGA
REFERENCE
REFERENCE
GAIN
GAIN
CONTINUOUS
CONTINUOUS
±1
±1
LOW-PASS
LOW-PASS
FILTER
FILTER
TIME
TIME
AD73322L
AD73322L
OUT
) is