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AMC1300: High Bandwidth Isolation Amplifier

Bright Chitura
Prodigy 70 points
Part Number: AMC1300
Other Parts Discussed in Thread: ISO120, ISO121, ISO224,

Hello,

I'm designing a high voltage(DC/AC) sensing circuit of signals that go up to 50kHz, However after doing simulation on TINA TI, it seems there starts to be a phase delay between the input and output signals after ~15kHz which corresponds to the datasheet. Is there an alternative option that I can use that is cheaper than the ISO120/ISO121 devices or additional components that would solve this issue?

Background: Designing circuit that can monitor input signals of up to ±1000V (DC and AC) up to 50kHz. The desired output will be ±10V which should be in phase with the input.

Thanks in Advance 

Bright C

  • 0
    TI__Guru**** 174841 points

    Hi Bright,

    Have you taken a look at the ISO224?  This is a newer devoce compared to the ISO12X parts and accommodates your desired +/-10V input needs.

  • 0 in reply to Tom Hendrick
    Prodigy 70 points

    Hi Tom,

    Yes I've also looked at the ISO224 and performed simulations using  TINA TI and still have the same issue of a phase difference between the input and output signals at 50kHz (image below). I know this is related to the frequency response of the device as both the magnitude and phase of the output signal have changed but i'm not sure if there's anything I can do about it without compromising accuracy besides looking for a better device.

    Kind Regards,

    Bright C

    50Hz Signal

    50kHz Signal

  • 0 in reply to Bright Chitura
    TI__Guru**** 174841 points

    Hi Bright,

    The delay is caused by the process of getting the original signal through the isolation barrier and to the outputs.  You would see this in the ISO12x devices as well.  What sort of maximum delay are you looking for?

  • 0 in reply to Tom Hendrick
    Prodigy 70 points

    Hi Tom,

    That makes sense, I'm looking for a maximum time delay that will keep the amplitude of the output signal within 1% of the ideal output. So the ideal amplitude would be 10V but since a time delay will always be present, I will be happy If the actual output is between 9.9V to 10.1V.

    Thank you for your quick replies.

    Kind Regards,

    Bright C

  • 0 in reply to Bright Chitura
    TI__Guru**** 174841 points

    Hi Bright,

    From the ISO224 to the AMC1300, there are slight differences in the delay times, but the gain tolerances are pretty tight so I don't have any reason to believe you can't reach your goals.  You would need less attenuation on the front end with the ISO224 than you would with the AMC1300.  Both devices have a similar differential output voltage swing so you would have a similar differential to single ended gain stage for both parts to get back to a +/-10V output signal.