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INA238: Transient voltage protection

Genius 14409 points
Part Number: INA238

Hi Experts,

A query received from customer as follows:

We are using the INA238 sensor on our application. The application produces transient voltage spikes that kill the sensor. Now, we are trying to add protection circuitry to avoid that. I have followed the recommendations included on the INA238 datasheet but I will thank you a lot if you could help me.

We want to use the full capabilities of the sensor. I attach the protection circuitry that we plan to test.

Could you recommend us any specific TVS for the INA238? Could we remove the ferrites beads?

Thank you for for support.

Regards,
Archie A.

  • Hi Art,

    if the INA238 becomes destroyed by a negative undervoltage at the inputs of INA238 (more negative than -0.3V !), then a bidirectional TVS will not protect the INA238.

    The best cure is to find the cause of damage and to eliminate this cause. In most cases unexpected inductive kick backs caused by neglected or even ignored wiring inductances does kill the INA238. So it would be wise to have a look at the wiring of INA238 and to move the INA238 to a position where the inductive kick backs are minimal.

    I know that adding a protection circuit seems reasonable at the first sight. But don't overlook that protection measures like fat Schottky diodes or fat TVS, e.g., come with huge parasitics and it's nearly impossible when using them to maintain the balance and symmetry of both inputs which can easily result in such a high loss of common mode rejection that the performance of circuit becomes totally ruined.

    Eventually, the INA238 should be replaced by a chip which can tolerate a higher common mode input voltage range and allows some minor inductive kick backs without getting destroyed.

    Can you tell us, what exactly kills the INA238? Do you have scope plots you can show here?

    Kai

  • Hello Archie,

    In general, I agree with Kai. We also have a design tool that can help you with transient protection, which can be found here: https://www.ti.com/tool/CIRCUIT060030

    If that is not enough for you, then reply to Kai's questions and send the requested scope shots.