REV.B

OP183/OP283

APPLICATIONS

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

10 k

Ω. This will give an adjustment range of approximately ±1 mV.

If larger adjustment span is desired, a 50 k

Ω potentiometer will

yield a range of

±2.5 mV.

Figure 37. Direct Access Arrangement

+5 Volt Only Stereo DAC for Multimedia

The 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. The 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

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

OP183

Figure 36. OP183 Offset Adjust

Phase Reversal

The 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

The OP183/OP283 can be used in a single supply Direct Access

Arrangement (DAA) as is shown in Figure 37. This 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 TXA is inverted by A2 and is not inverted by A3.

This arrangement drives the transformer differentially so that the

drive to the transformer is effectively doubled over a single amplifier

arrangement. This 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

OP283

OP283

OP283

750pF

0.33µF

0.1µF

0.0047µF

0.1µF

300pF

A1

A2

A3

RXA

TXA

SoundPort is a registered trademark of Analog Devices Inc.

1/2 OP283

+5V

1/2 OP283

OPTIONAL

GAIN

V

REF

1/2 OP283

+5V

V

REF

GAIN

1k

Ω

29

19

31

10µF

LOUT1L

LOUT1R

CMOUT

AD1849

V

REF

10µF

L VOLUME

CONTROL

R VOLUME

CONTROL

220µF

HEADPHONE

LEFT

220µF

HEADPHONE

RIGHT

8

1

4

3

2

1/2 OP283

Ω

330pF

100pF

7

5

6

1/2 OP283

330pF

100pF

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

LL

DL

CK

DR

LR

DGND

VBR

VBL

VOL

AGND

VOR

+5V SUPPLY

18-BIT

SERIAL

REG.

18-BIT

SERIAL

REG.

18-BIT

DAC

18-BIT

DAC

–9–