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UCD3138A: IC address allocation

Ella KIM
Expert 3862 points
Part Number: UCD3138A

Hi Team,

I just want to make sure how to allocate IC address to UCD3138A. 

Datasheet describes its address is allocated by a resistor on AD00 pin.

Customer used to use one UCD3138A. And they use AD00 abd AD01 for current sensing input for their buck topology, not for address allocation. (I'm newly taking the customer and don't know much of design history.) It doesn't cause any problem for customer and I wonder how the address is allocated in this case. I guess there should a default address for UCD3138A even before the firmware download. Is it correct? 

Currently, customer is going to use two UCD3138A. I guess they have to configure a resistor on AD00 pin to allocate two different address for each UCD3138A. Otherwise, there's no way to allocate the different address for each UCD3138A. Could you please check my understanding is correct? 

Thank you.

  • +1
    TI__Genius 13570 points

    Hi,

    Thanks for asking the question.  When one UCD3138A is used, this UCD3138A address can be assigned to a specific address from firmware, so there is no need for AD00 or AD01. When two UCD3138A are used, the addresses need be separated by using different resistors on AD00 or AD01. There is internal current source (10uA) connected to AD00 or AD01. When current source is enabled, ADC can measure the voltage produced on the pin and then assign an address to this UCD3138A based on the voltage. During normal operation, the current source is disabled, the AD00 or AD01 is used for  normal ADC.

      Regards,

    Sean

  • 0 in reply to Sean Xu
    TI__Expert 3862 points

    Hi Sean,

    Thank you for your reply. I believe the address can be allocated by ROM write as well even though AD00 or AD01 pin of two UCD3138A is configured with the same resistor. In other word, the address also can be allocated in SW, not in HW. Could you kindly confirm it.

  • +1 in reply to Ella KIM
    TI__Guru**** 189399 points

    Ella,

    No, if you have two devices in the system, you need to use AD00 and AD01 in order to set the addresses using physical resistors.

    Best regards,

    Don