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UCD9248: SMBAlert signal gets asserted while programming four UCD9248 controllers simultaneously.

Hammad Ali
Prodigy 20 points
Part Number: UCD9248

Hello everyone,

I am using four UCD9248 digital PWM controllers in my design to power up different rails of FPGAs DSP and ADC. To program the UCD9248 Controllers I am using TI USB-to-GPIO interface adapter EVM. The software platform which I am using is TI Fusion digital power designer.

I am facing a problem related to "SMBAlert" signal. I have programmed all the four controllers simultaneously. The controllers respond well . I have monitored the power status of all rails. The status is fine, there are no other faults appearing in the status registers except that the SMBAlert gets asserted. I have studied over the internet about the PMBus arbitration that the device with the lowest address gets the priority if multiple devices try to pull it down.Is it bad, that it gets asserted? If yes, then what should i do to remove it? Kindly help me out with this.

Thanks, Hammad.

  • 0
    TI__Genius 9845 points

    Hi Hammad,

    What do you mean by "programmed all the four controllers simultaneously"? Do the four devices have the same address? If so, the Alert may be due to a communication error. You should assign different addresses to each device.

    If you already assigned a unique address to each device, you can check the status of each device and find out which device asserted the Alert and triggered by what fault.

    Regards,

    Zhiyuan

  • 0 in reply to Zhiyuan Hu
    Prodigy 20 points
    Hello Zhiyuan,
    All the four devices connected to PMBus have been assigned unique addresses, all the devices assert this signal high when I program them. I want to know why it is being asserted?
  • 0 in reply to Hammad Ali
    TI__Genius 9845 points

    Alert is asserted when there is fault status generated inside the device. You can connect the Fusion GUI to the device, go to STATUS section, and check which status bit is set. Most status bits are self-explanatory. If not, please refer to PMBus 1.2 standard document for the explanation of the status bits.