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ADC128S102: Input clamp diode

Danilo A.
Mastermind 30020 points
Part Number: ADC128S102


Hi Team,

We received this inquiry from our customer.

We are using the ADC128S102WGRQV in a space application. During space flight a SET might occur on the OpAmp that is driving the ADC input.
During such event, the ADC input voltage might exceed the VA±0.3V so the ADC input diode might conduct for a brief period of time with a current in excess of ADC input diode 10mA rating.
Our driver could be driving up to 70mA for 2us though the ADC input diode clamp.

The 70mA diode current exceeds the 10mA ADC DC rating, but given the very short time duration (2us) we believe the heat generated in the ADC input diode will be insignificant. So exceeding the 10mA current for 2us will not damage the ADC input. Can you please confirm that?

Regards,

Danilo 

  • 0
    TI__Guru 64195 points

    Hi Danilo,


    Would you help confirm the customer for the ADC128S102 product? 

    Our recommendation must abide by the datasheet limits and we can't provide guidance to allow more than 10mA to flow through a given input pin for any amount of time.  2us is a pretty short period of time, but these structures are pretty tiny and can be damaged or shifted when used outside the datasheet guidance.

    Is it possible to limit the current with some added series resistance?  If not, how about an external clamp-to-rail diode which would clamp the analog inputs a diode drop above AVDD and help absorb most of the current from the voltage excursion?