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THS4541: impedance abnormally

Part Number: THS4541

Hi Team,

Customer have a THS4541IRGTR working abnormally. The phenomenon is that the impedance between the FB+ pin and the OUT+ pin increases significantly. Under normal circumstances, the impedance between the two pins is 8Ω when the power is off, and the impedance of the faulty chip increases to tens of kΩ. Have you experienced similar failures before? In what situation did this chip damage?

  • Hi Amelie,

    I don't think that impedance measurements between the pins of the THS4541 will tell anything useful. When the power is off connecting an Ohm meter between the pins of THS4541 will merely force the internal circuit to be biased in a way it would never be biased under normal operation. You could even destroy the THS4541 by this torture, if the Ohm meter drives a too high measurement current into the chip.

    The best way to find out wheter the chip is ok or not is to take a fresh THS4541 and check again. Impedance measurements with an Ohm meter, on the other hand, are not useful.

    The THS4541 becomes destroyed when the absolute maximum ratings are violated. So it would be helpful to see a schematic and to hear how the circuit is used.

    Kai

  • Hello Amelie and Kai,

      I agree a schematic would be very helpful and another method to test for internal damage is by measuring the impedance of each pin of the amplifier in reference to VS-. As Kai said, violating the abs max ratings of the device will destroy it, and most commonly we see either the input current or differential input voltage set too high which will destroy the internal ESD diodes and create a short between the rails.

    Thank you,
    Sima 

  • Hello Kai and Amelie,

      The conversation was taken offline by Sam Burnett.

    Thank you,
    Sima