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UCC28500: UCC28500 current amp

Viktor Nekromantik
Prodigy 40 points
Part Number: UCC28500

Tell me in solving the issue. In the datasheet SLUS419С p3 at the very bottom there is a table of parameters current amp. Open loop gain parameter. In the graph of test condition there is a value of Vcm = 0. What does this mean? Does this mean to set 0 volts on the ISENSE1 and MAOUT pins and measure the gain? So it's incorrigible. I ask for help in the decision. What is the open loop gain measurement mode?

  • 0
    TI__Guru* 86046 points

    Hello,

    I reviewed the data sheet and VCM generally refers to the common mode voltage.  Which is the average of the two inputs of the error amplifier.

    The UCC28500 current amplifier is inverting feedback and the + pin of the amplifier is connected to ground. The negative side of the current amplifier is tied to the multiplier resistor.  So when they tested this amplifier they put it in what was know as a forcing loop to test input offset voltage, bias current, input offset current, open loop gain etc...

    This does mean that ISENSE1 and MAOUT pin are at zero volts.  They will also be at zero volts in the normal application.

    Open loop gain is the maximum DC gain that you can get out of the current amplifier = 20Log*(Vout/(V+-(V-))

    Regards,

  • 0 in reply to Mike O'
    Prodigy 40 points

    Sorry, I do not quite understand what FORCING LOOP means? As I understand it, the current amplifier has negative feedback through the multiplier and other circuits having resistance, but do you specifically connect the pins MOUT and CAOUT thereby forming a negative feedback without unnecessary resistance and in this way the parameters are measured?