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Original question:

ADS1015: PGA

ADS1015: leakage current of AIN0/AIN1

Ben Kuo
Expert 7560 points
Part Number: ADS1015
Other Parts Discussed in Thread: ADS1013

Dear Expert,

Customer would like to estimate power consumption when system shot down.

They design ADS1013 for battery voltage monitor

Could you provide AIN0 leakage current? (VBAT=1.8V / VDD=0V)

Thanks!

Regards,

Ben

  • 0
    TI__Guru* 97595 points

    Ben,


    I assume that you're asking about what the input current might be if one of the analog inputs was at 1.8V and VDD is at 0V. This condition is beyond the absolute maximum ratings of the device. Note the maximum in the table below:



    If VDD is at 0V, the input shouldn't be greater than 0.3V. Within the device, there are ESD protection devices that look like the following:



    If AIN0 is at 1.8V, it will forward bias the diode to VDD. There is no current limiting inherent in this device. Even with series resistance at the input, it's likely that you would strongly forward bias the protection diode.

    If the supply is shut down, you should make sure there is no voltage on the inputs as well.


    Joseph Wu


  • 0 in reply to Joseph Wu
    TI__Expert 7560 points

    Hi Joseph,

    Thanks for point out the risk.

    Would you recommend suitable TI solution in my user case? *one of the analog inputs was at 1.8V and VDD is at 0V*

    Ben

  • 0 in reply to Ben Kuo
    TI__Guru* 97595 points

    Ben,


    I would still use the same device, but use series resistance from the input to the AINx pin of the ADC. A series resistance of 2kΩ should protect the ADC from that kind of over-voltage event. This would keep the input current to below 1mA, which is an order of magnitude below the absolute maximum of 10mA of input current.


    Joseph Wu