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AMC1200 EVM .

user676896
Prodigy 80 points
Other Parts Discussed in Thread: AMC1200, AMC1305M25, TMS320F28377D

I am designing a circuit to monitor current on a high voltage line ( 100VDC) and is testing with the AMC 1200 EVM .  Is it a must to have the input RC filtering at the amplifier input pins ? Can i remove and connect the shunt resistor directly to get faster response / BW ?

  • 0
    TI__Genius 9975 points
    Hello user676896,
    It is not a must to have the input RC filtering at the amplifier input pins; you can remove it.
    My recommendation would be to test your system with both configurations. Depending on the environment where your system operates, you might find that the input differential capacitor helps reduce the interference that high frequency noise could have.
    Bear in mind, however, that the cut-off frequency of the input RC filter (20 MHz) is much higher than the 100 kHz typical bandwidth of the AMC1200. The input RC filter should not slow down your differential input signal significantly.
    Best regards,
    Jose
  • 0 in reply to Jose Duenas
    Prodigy 80 points

    Hi Jose D. Thanks for feedbcak. I did a bench test with the EVM and found that AMC1200 response is slow even after removing the input filter components. 

    Is there a device that can be used to sense 1uSec transient currents as shown in picture below? Also noticed that the output waveform is different when sensing on the ground side current and when sensing on the high side ( 1000V) . I used two scope probes to measure pin 6 and 7 and used math funcion to show the output as Channel M1.

    Thanks

  • 0 in reply to user676896
    TI__Genius 9975 points

    Hello user676896,

    In order to sense a 1 us transient (even if it was a square signal), one needs a device with at least 1 MHz bandwidth. We do not have isolated amplifiers in that range.

    The alternatives we can offer would be either an isolated delta sigma modulator or an ADC used in conjunction with a digital isolator; the choice depends on the functionality and resolution you are looking for.

    If you need to acquire the shape of the transient then your best bet is an ADC with sampling frequency and resolution high enough to capture the desired number of samples during the 1 us event.

    If you are only interested in knowing whether the 1 us event exceeded a particular threshold, then an isolated delta sigma modulator may be sufficient. Devices such as the AMC1305M25 used in conjunction with the TMS320F28377D can be used to issue a digital signal when the input to the AMC1305M25 exceeds a particular, user-set, threshold.

    Hope this helps.

    Best regards,

    Jose