REV.B
OP183/OP283
APPLIC AT IONS
OP183 Offset Adjust
Figure 36 shows how the OP183’s offset voltage can be adjusted by
connecting a potentiometer between Pins 1 and 5, and connecting
the wiper to V
EE
. T he recommended value for the potentiometer is
10 k
. T his will give an adjustment range of approximately
±
1 mV.
If larger adjustment span is desired, a 50 k
potentiometer will
yield a range of
±
2.5 mV.
Figure 37. Direct Access Arrangement
+5 Volt Only Stereo DAC for Multimedia
T he OP283’s low noise and single supply capability are ideally
suited for stereo DAC audio reproduction or sound synthesis
applications such as multimedia systems. Figure 38 shows an 18-bit
stereo DAC output setup that is powered from a single +5 volt
supply. T he low noise preserves the 18-bit dynamic range of the
AD1868. For DACs that operate on dual supplies, the OP283 can
also be powered from the same supplies.
Figure 38. +5 Volt Only 18-Bit Stereo DAC
Low Voltage Headphone Amplifiers
Figure 39 shows a stereo headphone output amplifier for the
AD1849 16-bit SoundPort
Stereo Codec device. T he 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.
1
7
6
5
4
3
2
V
OS
V
CC
V
EE
OP183
Figure 36. OP183 Offset Adjust
Phase Reversal
T he OP183 family is protected against phase reversal as long as
both of the inputs are within the range of the positive supply and
the negative supply minus 0.6 volts. However if there is a possibility
of either input going beyond these limits, then the inputs should be
protected with a series resistor to limit input current to 2 mA.
Direct Access Arrangement
T he OP183/OP283 can be used in a single supply Direct Access
Arrangement (DAA) as is shown in Figure 37. T his figure shows a
portion of a typical DAA capable of operating from a single +5 volt
supply and it should also work on +3 volt supplies with minor
modifications. Amplifiers A2 and A3 are configured so that the
transmit signal T X A is inverted by A2 and is not inverted by A3.
T his arrangement drives the transformer differentially so that the
drive to the transformer is effectively doubled over a single amplifier
arrangement. T his application takes advantage of the OP183/283’s
ability to drive capacitive loads, and to save power in single supply
applications.
Figure 39. Headphone Output Amplifier for Multimedia
Sound Codec
20k
20k
3.3k
22.1k
20k
20k
OP283
OP283
OP283
750pF
475
0.33μF
0.1μF
2.5V
REF
0.0047μF
0.1μF
20k
37.4k
300pF
A1
A2
A3
RXA
TXA
SoundPort is a registered trademark of Analog Devices Inc.
1/2 OP283
+5V
1/2 OP283
5k
OPTIONAL
GAIN
1k
VREF
1/2 OP283
+5V
VREF
OPTIONAL
GAIN
1k
5k
29
19
31
10k
10μF
LOUT1L
LOUT1R
CMOUT
AD1849
VREF
10μF
10k
L VOLUME
CONTROL
R VOLUME
CONTROL
16
220μF
47k
HEADPHONE
LEFT
16
220μF
47k
HEADPHONE
RIGHT
47k
47k
8
1
4
3
2
1/2 OP283
7.68k
9.76k
330pF
100pF
7.68k
7
5
6
1/2 OP283
7.68k
9.76k
330pF
100pF
7.68k
LEFT
CHANNEL
OUTPUT
RIGHT
CHANNEL
OUTPUT
220μF
220μF
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
AD1868
V
L
LL
DL
CK
DR
LR
DGND
VBR
VBL
VOL
AGND
VOR
V
S
+5V SUPPLY
18-BIT
SERIAL
REG.
18-BIT
SERIAL
REG.
V
REF
18-BIT
DAC
18-BIT
DAC
V
REF
–9–