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shunt amplifier

Discussion in 'Electronic Design' started by Jamie Morken, Jan 2, 2004.

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  1. Jamie Morken

    Jamie Morken Guest

    Hi all,

    I am using a shunt to measure current and am wondering what would be a good
    amplifier to use for this. The shunt is on the ground side of the circuit
    and the max voltage differential on the voltage taps will be about 20mV (at
    20Amps/1mV shunt). I'd like to amplify this by 100X at 100kHz bandwidth or
    so. I have been using the max4194 variable amplifier up until now, but its
    datasheet specifies a max swing to only 200mV from the negative rail.

    Jamie Morken
  2. Use a SIMPLE Op-Amp with a bipolar supply.
    | __O Thomas C. Sefranek
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    (*)/ (*) Bicycle mobile on 145.41, 448.625 MHz
  3. James Meyer

    James Meyer Guest

    If you like the amplifier otherwise, then simply use a tiny switched cap
    voltage inverter from Maxim to get a negative supply for it. Then you can
    measure below ground as well.

  4. Fred Bloggs

    Fred Bloggs Guest

    You seem to be confused. The output swings rail-to-rail, and it is the
    input that can swing 200mV /below/ ( and not "from") GND. Since your tap
    does not exceed 20mv, this will not be a problem.
  5. Jamie Morken

    Jamie Morken Guest


    I think I was correct, this is right from the datasheet:

    The MAX4194-MAX4197 have rail-to-rail outputs and

    inputs that can swing to within 200mV of the negative rail

    and to within 1.1V of the positive rail.

    Input Voltage Range VEE + 0.2 VCC - 1.1 (Inferred from CMR test)

    Jamie Morken
  6. Robert Baer

    Robert Baer Guest

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