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  • TI Thinks Resolved

TCA9539: About the TCA9539 consumption

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Replies: 5

Views: 59

Part Number: TCA9539

question  1

when our device sleep,the current is about 36uA,but recently the current is about 300uA,we find the difference between these two device is the mark of TCA9539

question 2

How can TCA9539 be into standby mode,i did not find the register can be set。

  • Hello User,

    "we find the difference between these two device is the mark"

    PW9539 is the device marking (this matches what I see in our internal system for TCA9539PW)

    99K and 94K mean the Year/Month/Site the device was made.

    The last line symbolizes the lot number the device came from

    "when our device sleep,the current is about 36uA,but recently the current is about 300uA"

    Do you have a schematic of the TCA9539 you can provide? Typically when we see higher than normal current consumption, it is because the inputs are floating. Differences in devices can vary from lot to lot when there are consumption current concerns.

    "question 2

    How can TCA9539 be into standby mode,i did not find the register can be set。"

    There is no register to set this. Standby mode for our device just means that there is no I2C communication occurring.

    -Bobby

  • In reply to BOBBY:

    Hi 

       Bobby,the schematic as following,

       when our device into sleep,all the IO set to input。

       it is because the inputs are floating

      what the “inputs are floating“ mean? as usual ,when the device into sleep,all the IO should be set input,as your datasheet ,when IO set input ,it's  floating。should we set these IO as input pull-up or pull-down?

  • In reply to user6361226:

    Hello,

    "Floating" in this case means that there is no voltage applied.  The pins are configured as inputs but not pulled higher or low or biased via pull-up/down resistances, and so the voltage is not well-defined.  This can cause the voltage at the pin to be at an intermediate level between the supply and ground rails, and this condition tends to result in higher current consumption.

    Regards,
    Max

  • In reply to Max Robertson:

    Thank you, Max,

          In my case,when the device into sleep,all the pins unused set floating,so you means the higher current consumption is caused by these unused pins?should we set these unused pins input and pulled down?

  • In reply to user6361226:

    Yes, that's right.  You could either pull them high or low externally or just configure them as outputs instead of inputs (so that the device itself is driving a high or low level on these pins).  If you try that and don't see a reduction in supply current please let us know.

    Regards,
    Max

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