MUTE FUNCTION

A major feature of the LM1971 is its ability to mute the input

signal to an attenuation level of 102 dB. This is accom-

plished internally by physically disconnecting the output from

the input while also grounding the output pin through ap-

proximately 2 k

Ω.

The mute function is obtained during power-up of the device

or by sending any binary data of 0011 1111 and above seri-

ally to the device. The device may be placed into mute at any

time during operation, allowing the designer to make the

mute command accessible to the end-user.

DC INPUTS

Although the µPot was designed to be used as an attenuator

for signals within the audio spectrum, it is also capable of

tracking and attenuating an input DC voltage. The device will

track voltages to either supply rail.

One point to remember about DC tracking is that with a

buffer at the output of the µPot, the resolution of DC tracking

will depend upon the gain configuration of that output buffer

and its supply voltage. Also, the output buffer’s supply volt-

age does not have to be the same as the µPot’s supply volt-

age. Giving the buffer some gain can provide more resolu-

tion when tracking small DC voltages.

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