Level Shifter

Discussion in 'General Electronics Chat' started by ispymalik, Feb 1, 2011.

  1. ispymalik

    Thread Starter Member

    Apr 7, 2008
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    Is there a IC or custom Solution to shift between a 3V signal to ~20V?
    am i just overlooking the obvious?
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    Is this a power supply circuit? If so what are the current requirements for the 20V?

    Keeping up on your John Ringo reading? :D :p
     
  3. ispymalik

    Thread Starter Member

    Apr 7, 2008
    18
    0
    it will be digital signals no faster than 1 MHz.
    Power supply will be used up to 36V if necessary
    digital signal coming from ARM M.C. at 3V need it up to 20V

    Edit:
    Current is nA typ.,we will say mA to be conservative
    John Ringo?
     
    Last edited: Feb 1, 2011
  4. SgtWookie

    Expert

    Jul 17, 2007
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    So you have an input signal that is digital in a range of 0v to 3v?

    And you need the output swing to go from 0v to ~20v?

    Or you need to add 20v to the output signal level?
     
  5. ispymalik

    Thread Starter Member

    Apr 7, 2008
    18
    0
    input 0V or 3V

    need the output to go to
    20V for input 3V or
    0V for input 0V
    anyways to do this without a buck/boost converter?
    Thank you.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    That is a simple amplification function, all you need is an amplifier with a 20V power supply with a max digital rate of 1Mhz (edges are much faster). This sound correct?

    Malik is a word invented in the "Through the Looking Glass" through the "Claws that Catch" SciFi series. You might say I am an addict to all things John Ringo, David Weber, and Eric Flint. I could name a couple of others, but that would be off topic.
     
  7. ispymalik

    Thread Starter Member

    Apr 7, 2008
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    so, an opamp capable of the high voltage and make it with 20/3 gain?
    or a comparator with a 20V rail?
    Could i juse use a simple mosfet with 3V going to gate - 20V at Drain and have it the source go to the rest of my circuit?
     
  8. Wendy

    Moderator

    Mar 24, 2008
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    You need negative 20V? Doesn't matter a lot, but it does change some approaches. A comparator, for example, goes positive with a pull up resistor. You'll need some extra circuitry to go negative.

    Basically all of the approaches you suggest will work, except possibly for using op amps. 1Mhz is picky when using analog circuits. What are you driving in terms of load?
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    This won't work.
     
  10. Wendy

    Moderator

    Mar 24, 2008
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    Not even logic level MOSFETs?

    I'm still waiting for a verification of the -20V signal.
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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    Nope.
    Our OP is talking about having the source terminal connected directly to 20v, and use the drain for output.

    Even if our OP had a very low-threshold N-ch MOSFET, the source terminal would never go higher than 3v -threshold_voltage, so they would have a net loss of output voltage swing.
     
  12. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Couldn't a low side mosfet driver be used to do this? Instead of driving a mosfet the driver would just source the 20V from the gate terminal of the driver. All in one package powered from his uC.
     
  13. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    What is the load on your 20V signal?
     
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