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[ TS12A4514 ] Excess Current Drawing when voltage on logic pin doesn't equal Vcc

[ TS12A4514 ] Excess Current Drawing

Hi,

Can you help to the behavior reported from my customer with TS12A4514?

* TS12A4514
* V+ = 10V
* IN = 3.3V
* Current Drawing = > 100mA

From specification for V+12V, it's specified that the threshold of Input logic high is 5V. So it's assumed that for V+=10V case, this 3.3V is not enough voltage to turn switch on, and it's in undefined state.
However, I cannot explain that this condition cause excess current drawing. Can anyone have ideas?

Thank you for your support in advance.
Regards,
Ken

  • Ken,

    You are correct with a 10V supply 3.3V on the IN pin is not enough to make it a valid logic state.  You will need to raise the voltage on the IN >5 V to place the IC in a valid logic state. 

    Leaving the IN pin floating can cause excessive current draw in the 1-20mA range.  If you are seeing 100mA I suspect you may have damaged the IC by having it in an undefined state drawing 10s of mA which violates the abs max rating in the datasheet. 

    You can see this app note "Implications of Slow or Floating CMOS inputs" for more information on this phenomenon.


    Have you tried replacing the potentially damaged IC and see if it will operate in your system with the appropriate logic voltage level?

    Thank you,

    Adam

  • In reply to Adam Torma:

    Thanks Adam.

    The app. note is helpful for me to understand customer behavior.

    Regards,
    Ken

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