LM7341 datasheet(15/20 Pages) NSC

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Typical Applications

HANDHELD REMOTE CONTROLS

The LM7341 offers outstanding specifications for applications

requiring good speed/power trade-off. In applications such as

remote control operation, where high bandwidth and low pow-

er consumption are needed. The LM7341 performance can

easily meet these requirements.

OPTICAL LINE ISOLATION FOR MODEMS

The combination of the low distortion and good load driving

capabilities of the LM7341 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 distor-

tion at high output drive currents, the LM7341 fulfills this need,

in this and in other telecom applications.

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 re-

duces 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 LM7341

offers the tiny package, higher bandwidths, and greater out-

put drive capability than other rail-to-rail input/output parts can

provide for this application.

LM7341 AS A COMPARATOR

The LM7341 can also be used as a comparator and provides

quite reasonable performance. Note however that unlike a

typical comparator an op amp has a maximum allowed dif-

ferential voltage between the input pins. For the LM7341, as

stated in the Absolute Maximum Ratings section, this maxi-

mum voltage is V

IN Differential = ±15V. Beyond this limit, even

for a short time, damage to the device may occur.

As an inverting comparator at V

S = 30V and 1V of overdrive

there is typically 12

μs of propagation delay. At V

S = 30V and

50 mV of overdrive there is typically 17 µs of propagation de-

lay.

20206054

FIGURE 1. Inverting Comparator

Similarly a non-inverting comparator at V

S = 30V and 1V of

overdrive there is typically 12 µs of propagation delay. At

S = 30V and 50 mV of overdrive there is typically 17 μs of

propagation delay.

20206055

FIGURE 2. Non-Inverting Comparator

COMPARATOR WITH HYSTERESIS

The basic comparator configuration may oscillate or produce

a noisy output if the applied differential input voltage is near

the comparator's offset voltage. This usually happens when

the input signal is moving very slowly across the comparator's

switching threshold. This problem can be prevented by the

addition of hysteresis or positive feedback.

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