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INA302: ALERT2 working principle

Yogesh M R1
Prodigy 20 points
Part Number: INA302

Hi,

We have implemented INA302 for over current protection in our design.

The LIMIT2 is set for 40A current limit. The LATCH2 pin is tied to GND (Transparent mode)

The Delay pin has been connected to a 10uF capacitor to provide 2.44s delay.

If there is a surge current exceeding 40A (say for 100us), our expectation is that ALERT2 signal should not be asserted as we have set a time delay of 2.44s.

But what we observe is that the ALERT2 is asserted after 2.44s even though the surge current doesn't exist beyond 100us.

We have replaced the IC and find the same behavior with the new IC as well.

Is this the expected behavior of the IC? if yes, then what is the purpose of the Delay?

Thanks,

Yogesh M R

  • 0
    TI__Mastermind 21760 points
    Hello Yogesh,

    Thanks for considering to use Texas Instruments. To answer your question I need a few more details. What is the value of your shunt resistor and what is your typical current level? One possible explanation would be that the current never dipped low enough to cause your Vout to cross the hysteresis threshold. If this threshold is not crossed then its possible that the device would assert the alert. However, if Vout goes 100mV lower than the VLimit, I would not expect the Alert to assert. If this is in fact occurring, to better understand your condition I will need an oscilloscope shot of your Vout, Vsense, and Vlimit.
  • 0 in reply to Patrick Simmons
    Prodigy 20 points

    Hi Patrick,

    Thank you very much for the response. We had not considered the 100mV Hysteresis of the Comparator.

    Thanks and Regards,

    Yogesh M R