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ADC128S102QML-SP: What happens when VA supply drops momentarily (15ms)

Jeffrey Lu
Prodigy 30 points
Part Number: ADC128S102QML-SP

Our system can experience a 15mS power drop to the VA line in a dual supply topology. (VA=5V, VD=3.3V)

In this case, we are out of spec where VD is now greater than Va by much more than 300mV as per the datasheet. 

- Will we be causing damage to the chip as the this will cause the ESD diodes to conduct since we could be driving the inputs when only VA is down? 

- if we cause damage in the first scenario, our mitigation involves removing the 3.3V rail to the part when the 5V rail drops, however we will still be driving the inputs when both VA and VD are down, will this cause damage to the part?

thanks,

Jeff

  • 0
    TI__Mastermind 25020 points

    Hello,

    Violating the device specs is not ideal, in any scenario. If this occurs, especially for long periods of times then this can decrease the longevity of the device. When an abs mas is violated, we cannot predict the behavior of the device.

    In both scenarios the ESD is being activated, given the situation, the second scenario provided would be best.

    In this case, the ESD structure will redirect the current to the power supply, thus is it important that the AVDD power rail is able to sink current. The current should also me limited to the inputs. The device would not be violating any abs max, and should be able to recover with minimal risks.

    Regards

    Cynthia