LM7301

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SNOS879H – AUGUST 1999 – REVISED MARCH 2013

OPTICAL LINE ISOLATION FOR MODEMS

The combination of the low distortion and good load driving capabilities of the LM7301 make it an excellent

choice for driving opto-coupler circuits to achieve line isolation for modems. This technique prevents telephone

line noise from coupling onto the modem signal. Superior isolation is achieved by coupling the signal optically

from the computer modem to the telephone lines; however, this also requires a low distortion at relatively high

currents. Due to its low distortion at high output drive currents, the LM7301 fulfills this need, in this and in other

telecom applications. Please refer to STABILITY CONSIDERATIONS for methods used to ensure stability under

all load conditions.

REMOTE MICROPHONE IN

PERSONAL COMPUTERS

Remote microphones in Personal Computers often utilize a microphone at the top of the monitor which must

drive a long cable in a high noise environment. One method often used to reduce the nose is to lower the signal

impedance, which reduces the noise pickup. In this configuration, the amplifier usually requires 30 db–40 db of

gain, at bandwidths higher than most low-power CMOS parts can achieve. The LM7301 offers the tiny package,

higher bandwidths, and greater output drive capability than other rail-to-rail input/output parts can provide for this

application.

Copyright © 1999–2013, Texas Instruments Incorporated

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