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# What is the function of R5 (3.32K) in below opamp based circuit?

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#### jay1691

##### Member level 2
What is function of R5(3.32K) in below opamp based circuit ?

Hi All,

Please find attached schematic.

Here i gave 0-10V analog DC as input. Output is set 3.28V for 10V input.

Here i can't understand exact role of R5(3.32K) in this function.Please help me out.

Re: What is function of R5(3.32K) in below opamp based circuit ?

It depends on what the circuit drives next. The most likely reason is it's there to isolate the output of the op-amp from a reactive load. If it was left out and a capacitive load or an inductive load was applied it could make the circuit unstable or too much output current might flow. Placing it inside the feedback loop helps to counteract the voltage drop across R5 so the DC stability is maintained.

Brian.

jay1691

### jay1691

Points: 2
Re: What is function of R5(3.32K) in below opamp based circuit ?

Hi Brian,

Thanks. Yes, It is driving inductive load. So i got your answer.
Is that (3.32K) effect to output ? Or i can say that in theoretical calculation of Vout ?

Let's say for non inverting amplifier, Vout = (1+Rf/R1) vin
So what is the value of Rf and R1 in our circuit ?

Re: What is function of R5(3.32K) in below opamp based circuit ?

3.32k resistor will not exist in gain formula. It only limits output current of inverting amplifier. In other words output voltage will be limited to some max value.

jay1691

### jay1691

Points: 2
Re: What is function of R5(3.32K) in below opamp based circuit ?

Hi Borber,
please help me how to calculate the limited max output voltage when R5(3.32K) exist?
thank you !

jay1691

Points: 2