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Original question:

[FAQ] TPS23861: When using I2C scan to discover I2C devices on the bus, why do we receive extra ACK from address 0x30?

TPS23861: Device is only semi-responsive

Carolus Andrews
Mastermind 22470 points
Part Number: TPS23861

Team,

I have a customer working with TPS23861, and is running into the following issue: they can see the device on its broadcast(0x30), and if they write 0xAA with an address, it takes the command (it ACKs). Apart from that though, it does not seem to be doing anything. They do not see AOUT go low to program in the slave addresses. Any thoughts?

  • 0
    TI__Expert 5615 points
    Greetings Carolus and thank you for your local support.

    Penny Xu is our PSE Application Engineer and she is in transit, coming back from business travel, today. She is assigned this thread and will help you work toward resolution upon her return. Look for a post from her tomorrow (9/27).

    For now, I would encourage you to check the customer's startup sequence and - in particular - to ensure the customer has read our application notes on the topic when it comes to this device. Two documents I would suggest are www.ti.com/.../slva723 and www.ti.com/.../slua788 . While improper startup may not be the root cause here, it is good to eliminate it while Penny is on her way back to give deeper assistance. An improper startup sequence is known to corrupt some registers in the TPS23861...which can cause an assortment of strange system behavior...this is why I seek to eliminate it as a potential cause of concern.

    I will also send you a .ppt document on this phenomenon - so that you have a better idea what to look for - through TI email.

    Nice to hear from you again,
  • 0 in reply to Thomas Lewis
    TI__Mastermind 22470 points

    Thanks for the response Thomas! I'll review power up sequences and look to follow up with Penny tomorrow.