OP113/OP213/OP413
Rev. F | Page 17 of 24
LOW VOLTAGE HEADPHONE AMPLIFIERS
Figure 49 shows a stereo headphone output amplifier for the
AD1849 16-bit SOUNDPORT® stereo codec device.
1
The
pseudo-reference voltage is derived from the common-mode
voltage generated internally by the AD1849, thus providing a
convenient bias for the headphone output amplifiers.
5V
5kΩ
OPTIONAL
GAIN
1kΩ
5V
5kΩ
29
19
31
10kΩ
LOUT1L
LOUT1R
CMOUT
AD1849
16Ω
47kΩ
HEADPHONE
LEFT
HEADPHONE
RIGHT
16Ω
47kΩ
+
OPTIONAL
GAIN
1kΩ
V
REF
10µF
V
REF
10kΩ
10µF
L VOLUME
CONTROL
1/2
OP213
1/2
OP213
1/2
OP213
R VOLUME
CONTROL
V
REF
220µF
+
220µF
–
+
–
+
–
+
00286-048
Figure 49. Headphone Output Amplifier for Multimedia Sound Codec
LOW NOISE MICROPHONE AMPLIFIER FOR
MULTIMEDIA
The OPx13 family is ideally suited as a low noise microphone
preamp for low voltage audio applications.
Figure 50 shows a
gain of 100 stereo preamp for the AD1849 16-bit SOUNDPORT
stereo codec chip. The common-mode output buffer serves as a
phantom power driver for the microphones.
5V
10k
50Ω
20Ω
100Ω10kΩ
5V
20Ω
50Ω
10kΩ
10kΩ
100Ω
15
17
MINL
MINR
CMOUT
AD1849
19
LEFT
ELECTRET
ONDENSE
MIC
INPUT
10µF
+
10µF
+
1/2
OP213
1/2
OP213
–
+
RIGHT
ELECTRET
CONDENSER
MIC
INPUT
+
–
1/2
OP213
–
+
00286-049
Figure 50. Low Noise Stereo Microphone Amplifier for Multimedia Sound
Codec
PRECISION VOLTAGE COMPARATOR
With its PNP inputs and 0 V common-mode capability, the
OPx13 family can make useful voltage comparators. There is
only a slight penalty in speed in comparison to IC comparators.
However, the significant advantage is its voltage accuracy. For
example, V
OS
can be a few hundred microvolts or less, combined
with CMRR and PSRR exceeding 100 dB, while operating from
a 5 V supply. Standard comparators like the 111/311 family
operate on 5 V, but not with common mode at ground, nor with
offset below 3 mV. Indeed, no commercially available single-
supply comparator has a V
OS
less than 200 V.
1
SOUNDPORT is a registered trademark of Analog Devices, Inc.
