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PGA305: Chip reset when diagnostic is enabled

Matteo Cardani1
Prodigy 20 points
Part Number: PGA305

Hello,

I'm currently facing this issue working with PGA305:

When diagnostic is enabled, the component seems to reset itself. In fact I see on oscilloscope the BRG+ falling from 2.5V to 0V for about 6ms, and then rising again to 2.5V. Reading the component during this period, obviously gives me a 0 sample. I'm using the 0x00- ReadPADCSourceValue to read the component.

When disabling diagnostic, I'm not seeing this behaviour. 

I'm reading PGA305 through emulated I2C at 25khz. I haven't seen any issue looking at the signal with my scope, and interpreted command seems fine.

May you give me support as this issue is jeopardazing our project?

Thank you

  • 0
    TI__Mastermind 31655 points

    Hello Matteo,

    When does the PGA305 seem to reset itself? Does this happen immediately after enabling the diagnostics and only once? Does it happen at a specific time during normal operation, but only when the diagnostics have been enabled? Can you please give some more detail about the conditions surrounding the reset?

    Thank you,

  • 0 in reply to Scott Cummins
    Prodigy 20 points

    Hello Scott,

    thank you for your kind reply.

    The PGA seems to reset itself during operation while diag_enable register is set. If fact under this condition I can see BRG+ falling from 2.5V to 0V and then going back to 2.5V. This seems to happen randomly during operation and seems correlated to the interrogation frequency of the sensor, It happens more often when reading frequency is higher.

    Other behaviour I saw today is that sometimes PGA305 answer with a NACK to the reading command. In this case I do not continue the reading operation and send a stop. Howevere it seems not to be related to voltage falling.

    Just to be clear, I'm sending a NACK after reading Salve Data, but in the datasheet I just saw that it is not reported and it is sent just a stop command. Could this cause some issue?

    Thank you

    Best regards,

    Matteo Cardani