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TCA9534: I2C DIO - is not providing an ACK

Mark Stanczak
Intellectual 420 points
Part Number: TCA9534

I am having difficulty communicating with the TCA9534.  I am probing the I2C Clock and Data lines.  I can see the Master has initiated the Start Condition.  I can see that the slave address is clocked out.  I can see the Write command bit is 0.  The TCA9534 is not holding the Data Line low on the next clock cycle to provide an ACK.  I have another I2C device working on this bus, so the bus is working.  I am seeking help with understanding what is going on so I can get this chip working.

  • 0
    TI__Guru 62920 points

    Hi Mark,

    Could we please take a look at the SDA/SCL waveforms to see if anything may be amiss?  We could review the schematic as well if you are OK with sharing the relevant portion of it.

    Some basic things to check would be confirming the address used is correct (per the A2:0 pin configuration), confirming the "low" level input voltage is low enough (<0.3*VCC), and confirming the power ramp at start-up is within the requirements detailed in Section 10 of the datasheet.

    Regards,
    Max

  • 0 in reply to Miguel Robertson
    Intellectual 420 points

    Hi Max,

    I found the problem.  We're testing this chip for our application.  I thought a TCA9534 was stuffed.  It was a TCA9534A, which has a different slave address.  That corrected the confusion I was having.  Thanks for the quick response.

  • 0 in reply to Mark Stanczak
    TI__Guru 62920 points

    Mark,

    Thanks for following up with the resolution.  I'm glad it was a simple answer!

    Regards,
    Max