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Question about 50-Ω input termination.

Piotr Falkowski1
Prodigy 30 points
Other Parts Discussed in Thread: THS4521

Hello,
I have problem with 50-Ω input termination in the THS4521 amplifire.

I want to conect the current sensor (ACS770 from Allegro) to the THS4521 amplifire  but  the ACS770 has limitaions for output current.

But If I will use 50Ω termination the ACS770 will be overloaded. Is there any solution for this.

Best regards, Piotr

 

  • 0
    TI__Mastermind 23226 points
    Hi Piotr,

    So I understand correctly, are you connecting the output of the sensor directly to the input of the FDA? If that is true, you can eliminate the 50 ohm shunt resistor and just use large enough gain resistors to limit your sensor's load current below 6mA. You only need a 50 ohm termination when the source impedance is 50 ohms and the trace length is longer than a quarter of the signal wavelength. Since this is a low frequency application, impedance matching is not necessary.

    Best regards,

    Sean
  • 0 in reply to Sean Cashin
    Prodigy 30 points

    Yes you correctly understood my problem.

    In my application (DC/AC PV inverter) I want to transfer a signal from the current sensor to microcontroler.

    I want use the THS4521 to prevent analog signal from noise.

    Thank for very helpful response.

    Piotr