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UCC28951: UCC28951/TMS320F28034PNT current sense using differential amplifier

Andrew Lau
Prodigy 50 points
Part Number: UCC28951

Tool/software:

Hi,

Due to high power density, could we use differential amplifier to sense primary current in current mode of UCC28951/TMS320F28034PNT

instead of current transformer?

Thanks

  • 0
    TI__Guru* 85616 points

    Hello,

     

    For high current designs using a current sense transformer is the preferred method.  This will step down the current be being measured through the current sense transformer’s turns ratio (Nct).

     

    Nct = V1/V2 = N1/N2 = I2/I1

     

    Using the current sense transformer will allow you to use a larger current sense resistor/signal with lower power dissipation compared to using a shunt off line as you are suggesting.

     

    If you use a differential mode amplifier you will need a much smaller current sense resistor to reduce power dissipation.  You will to gain up the current sense signal through the amplifier.  This technique is not popular because it tends to be noise sensitive and I would not recommend it.

     

    Regards,