LM7171 - Follower

Asked Oct 21 '21 at 10:15

Active Oct 21 '21 at 11:24

Viewed 42 times

I am trying to isolate part of my circuit with a voltage follower (LM7171). The signal at the op amp non-inverting input is PWM (12 V, 0 V) with a frequency of 20 kHz. It is attenuated by the voltage divider (6 V, 0 V) when the op amp is not connected.

When the op amp is connected to (+12 V, 0 V), the PWM at the non-inverting pin shifts from (6 V, 0.9 V). What's causing this offset in the PWM?

I thought it was caused by the grounds but I have disregarded it already by connecting all the grounds as close as possible.

edited Oct 21 '21 at 11:24

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asked Oct 21 '21 at 10:15

Jonw3

(inspection of the datasheet tells you that the input and output voltage ranges of the LM7171 do not reach the negative supply voltage. So, this is very expected and documented!) – Marcus Müller Oct 21 '21 at 10:28
LM7171 : Specified for ±15V and ±5V Operation – Marko Buršič Oct 21 '21 at 11:10
Why use an opamp to process PWM signal? You will get terrible accuracy near 0% and 100% due to slew rate. – bobflux Oct 21 '21 at 11:27

LM7171 - Follower

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