# Problem in designing proper voltage shifter

1. ## Problem in designing proper voltage shifter

Hello everyone,

I want to design a voltage level shifter which has a input of 0-12V (variable) and convert it to 0-3.3V, by keeping the level proportionate (12/3.3). I have simulated a circuit using multisim, and got the result. But it practically difficult, because the opamp (3554am) I have used here is obsolete now. Can you please suggest me any Opamp which will work for this problem, or any other reference design for the same.

Thank you.

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2. ## Re: Problem in designing proper voltage shifter

Originally Posted by MD_SHAHRUKH

I want to design a voltage level shifter which has a input of 0-12V (variable) and convert it to 0-3.3V, by keeping the level proportionate (12/3.3).
op amp 3554Am has a gain-bandwidth product of 1.7 GHz and a slew rate of 1000 V/us
what is the highest frequency you expect to use in this circuit?
are there any other requirements of the op amp you haven't stated?

How about a resistor divider and a voltage follower?
Resistors about 3300 ohm and 8700 ohm? then Vout = 3300/12000 - the proportion you want
you might need more than one resistor to get 8700 ohm, as 8700 is not a standard value.

op amp suggestions will depend on the frequency range and other quantities not yet specified

i suggest you power it between 15V and -5V, so that 0V is included in the range and
you're not depending on a "rail to rail" device.

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3. ## Re: Problem in designing proper voltage shifter

The scenario is I have an input voltage signal which is varying from 0V to 12V DC, I want to give the signal to a builtIn ADC of a microcontroller development board, but I can not change the Vref of ADC. So, I planned to convert the 0-12V signal voltage level to the 0-3.3V voltage level.

what is the highest frequency you expect to use in this circuit?
It has no frequency. There is no oscillation in the signal.

are there any other requirements of the op amp you haven't stated?
I supposed to make this conversion using Op-Amp, but I am not sure whether i is feasible to use Op-Amp this way.

How about a resistor divider and a voltage follower?
Is resistor divider reliable? I mean according to my requirement?

Thank you.

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4. ## Re: Problem in designing proper voltage shifter

Hi,

0...12V to 0....3V3?

The best I can recommend is a two resistor voltage divider.
Every Opamp and every other device will additionally introduce errors.
This meets all your given requirements.

I mean according to my requirement?
What requirement exactly are you talking about?

Klaus

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5. ## Re: Problem in designing proper voltage shifter

your signal varies from 0 V to 12 V
how fast does it vary?
or, how often does it change?

Klaus is correct, a resistor divider is the simplest solution
i like the op amp follower so you do not load the divider, as i know nothing about the input stage of your processor

the resistor divider is reliable
you can build it from standard 1% or 0.1% resistors
you can get resistors with very good temperatures coefficients
it comes down to a trade-off between cost, availability and requirements

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6. ## Re: Problem in designing proper voltage shifter

You make no mention of required accuracy or ADC resolution; THAT will determine what opamp you need. But you certainly don’t need TWO GHz amps.

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