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AMC1301: AMC1301: Power Supply Recommendation

Jason Tribe
Prodigy 220 points
Part Number: AMC1301

Hi,

We have a three phase inverter with line voltage and line current sensing using the AMC1301 isolated amplifiers.

The voltage is sensed using a voltage divider and the current is sensed using inline current sense resistors. The current sense resistors are inline with the output phases and not in the emitter leg paths.

The driver circuitry is power using a 16V supply. The AMC1301's doing the voltage sensing are powered from a non-isolated 3V3 rail derived from the 16V rail and the current sensing AMC1301's are powered using 3V3 zener diodes driven from the floating, high side driver rails just like the suggestions in the AMC1301 datasheet.

My question is if we already have a non-isolated 3V3 rail for the voltage AMC1301's can we use this same rail to power the current sensing AMC1301's instead of using zener regulators? Does powering the current sensing AM1301's from the floating, high side driver supply add some sort of noise or common mode voltage immunity to the sensing circuit?

Any feedback or comments on this would be greatly appreciated.

Thanks 

Jason

  • 0
    TI__Guru**** 181021 points
    Hi Jason,

    The high side ground of the AMC1301 is normally tied to the shunt, so in the case of your voltage monitor, I suspect that's associated with your DC return from the bridge. On the currents though, the floating supplies are there to maintain some level of isolation between the phases. Also, the common mode input voltage to the AMC1301 is limited to VDD1 so you couldn't use the same power rail as the voltage monitor.