• State TI Thinks Resolved
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 48 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

ADC081C021: when ADC is not powered, the analog input draw a lot current from the battery

analogsp
Prodigy 10 points
Part Number: ADC081C021

Tool/software:

Hello, 

I have a RTC circuit to continue clock when the system is off, I have also battery monitoring circuit to read battery voltage using ADC081C021. The problem I have faced is when the system is not powered, analog input of this IC draw hundreds level microamps from my battery. I wonder why this consumption occurs. My adc circuit is attached. the 5V_ADC is system power, it is zero when the system is not powered. 

  • 0
    TI__Intellectual 2590 points

    Hello,

    Can you verify if I understand correctly? When voltage is removed from VA, you are seeing that the device is drawing current from your battery connected to the VIN pin.

    If so, this is due to the internal ESD structure of this device. If the battery is connected to VIN while VA is connected, then the absolute maximum ratings are likely being violated, causing diode D1 to conduct and drawing excess current from your input. 


    My recommendation is to implement a mechanism to remove the signal at VIN after power at VA has been removed.

    Regards,
    Joel

  • 0 in reply to Joel Meraz
    Prodigy 10 points

    Thank you for your answer. I thought the situation you mentioned above and add schottky to VA to cut forward biased D1. the current drawn is reduced but still a lot current is drawn.