+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Member level 1
    Points: 652, Level: 5

    Join Date
    Jun 2017
    Location
    Bhubaneswar, India
    Posts
    39
    Helped
    4 / 4
    Points
    652
    Level
    5

    Problem in designing proper voltage shifter

    Click image for larger version. 

Name:	opamp_12_3v.png 
Views:	6 
Size:	28.2 KB 
ID:	155249
    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 But it practically difficult, because the opamp (3554am) I have used here is obsolete now.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.

    •   AltAdvertisement

        
       

  2. #2
    Full Member level 6
    Points: 2,031, Level: 10

    Join Date
    Jan 2019
    Posts
    377
    Helped
    94 / 94
    Points
    2,031
    Level
    10

    Re: Problem in designing proper voltage shifter

    Quote Originally Posted by MD_SHAHRUKH View Post

    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.


    1 members found this post helpful.

    •   AltAdvertisement

        
       

  3. #3
    Member level 1
    Points: 652, Level: 5

    Join Date
    Jun 2017
    Location
    Bhubaneswar, India
    Posts
    39
    Helped
    4 / 4
    Points
    652
    Level
    5

    Re: Problem in designing proper voltage shifter

    Thank you for your reply.

    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.



    •   AltAdvertisement

        
       

  4. #4
    Super Moderator
    Points: 77,800, Level: 68
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    15,765
    Helped
    3590 / 3590
    Points
    77,800
    Level
    68

    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
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.


    1 members found this post helpful.

  5. #5
    Full Member level 6
    Points: 2,031, Level: 10

    Join Date
    Jan 2019
    Posts
    377
    Helped
    94 / 94
    Points
    2,031
    Level
    10

    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


    1 members found this post helpful.

    •   AltAdvertisement

        
       

  6. #6
    Advanced Member level 5
    Points: 24,271, Level: 37
    barry's Avatar
    Join Date
    Mar 2005
    Location
    California, USA
    Posts
    4,655
    Helped
    1032 / 1032
    Points
    24,271
    Level
    37

    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.


    1 members found this post helpful.

--[[ ]]--