OP113 Datasheet, PDF (8/16 Pages) Analog Devices – Low Noise, Low Drift Single-Supply Operational Amplifiers

OP113/OP213/OP413
Low Voltage Headphone Amplifiers
Figure 9 shows a stereo headphone output amplifier for the
AD1849 16-bit SoundPort^® Stereo Codec device. The pseudo-
reference voltage is derived from the common-mode voltage
generated internally by the AD1849, thus providing a conve-
nient bias for the headphone output amplifiers.
OPTIONAL
GAIN
1k⍀
V_REF
LOUT1L 31
10␮F
10k⍀
L VOLUME
CONTROL
5k⍀
+5V
1/2
OP213
16⍀
220␮F
+
47k⍀
HEADPHONE
LEFT
AD1849
V_REF
+5V
1/2
OP213
CMOUT 19
10k⍀
LOUT1R 29
10␮F
R VOLUME
CONTROL
1/2
OP213
5k⍀
1k⍀ _OPTIONAL
GAIN
V_REF
16⍀
220␮F
+
47k⍀
HEADPHONE
RIGHT
Figure 9. Headphone Output Amplifier for Multimedia
Sound Codec
Low Noise Microphone Amplifier for Multimedia
The OP113 family is ideally suited as a low noise microphone
preamp for low voltage audio applications. Figure 10 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.
LEFT
ELECTRET
CONDENSER
MIC
INPUT
RIGHT
ELECTRET
CONDENSER
MIC
INPUT
10␮F _50⍀
20⍀
10k⍀
+5V
1/2
OP213
20⍀
10␮F
10k⍀
50⍀
10k⍀
+5V
1/2
OP213
100⍀
100⍀
1/2
OP213
17 MINL
AD1849
19 CMOUT
15 MINR
10k⍀
Precision Voltage Comparator
With its PNP inputs and zero volt common-mode capability, the
OP113 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 on
5 V supply. Standard comparators like the 111/311 family oper-
ate on 5 volts, 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 µV.
Figure 11 shows the OP113 family response to a 10 mV over-
drive signal when operating in open loop. The top trace shows
the output rising edge has a 15 µs propagation delay, while the
bottom trace shows a 7 µs delay on the output falling edge. This
ac response is quite acceptable in many applications.
+2.5V
0V
–2.5V
t_r = t_f = 5ms
؎10mV OVERDRIVE
+5V
25k⍀
100⍀
1/2
OP113
2V
100
90
5␮s
10
0%
2V
Figure 11. Precision Comparator
The low noise and 250 µV (maximum) offset voltage enhance
the overall dc accuracy of this type of comparator. Note that
zero crossing detectors and similar ground referred comparisons
can be implemented even if the input swings to –0.3 volts below
ground.
Figure 10. Low Noise Stereo Microphone Amplifier for
Multimedia Sound Codec
SoundPort is a registered trademark of Analog Device, Inc.
–8–
REV. C