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

10µF

10kΩ

10µF

L VOLUME

CONTROL

1/2

OP213

1/2

OP213

1/2

OP213

R VOLUME

CONTROL

220µF

+

220µF

–

+

–

+

–

+

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

10kΩ

50Ω

20Ω

100Ω

10kΩ

5V

20Ω

50Ω

10kΩ

10kΩ

100Ω

15

17

MINL

MINR

CMOUT

AD1849

19

LEFT

ELECTRET

CONDENSER

MIC

INPUT

10µF

+

10µF

+

1/2

OP213

1/2

OP213

–

+

RIGHT

ELECTRET

CONDENSER

MIC

INPUT

+

–

1/2

OP213

–

+

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

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-