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TMS320F28075: What is the required VDDIO low consistent time to trigger BOR?

Brian Wang0
Expert 5540 points

Part Number: TMS320F28075

Hi team,

My customer monitored f28035 BOR in their products. And they did noticed voltage below Vddio <2.96 which is the BOR trigger point of <1us. 

They would like to know, from design point of view, what is the trigger window for BOR? Is it like an comparator, or it requires a period of time? Cause they need to decide, whether the Vddio low is the root cause to their products failure.

Regards,

Brian 

  • 0
    TI__Mastermind 28275 points

    Hi Brian,

    The heading for your post mentions F28075 but your question talks about F28035. Can you clarify which device your BOR question is about?

  • 0 in reply to Frank Ankapong
    TI__Expert 5540 points

    Hi Frank,

    It's actually F28035. Sorry about the misunderstanding.  Due to time zone, it would take one day to get your answer. And this case is very urgent. Please kindly help to update this info.

    Update the test result here. As we can noticed on the scope(green channel), there are few spikes on Vddio which would cause the voltage to fall below 2.8V. Customer would like to confirm whether this would trigger the BOR. Understood anything out of the SPEC may cause an unknown condition. But we need your confirmation, from design perspective, about how BOR would be triggered.

    Regards,

    Brian

  • 0 in reply to Brian Wang0
    TI__Mastermind 28275 points

    Brian,

    Thanks for clarifying. On the F28035 device, the VDDIO BOR range is 2.5v to 2.96v. If the VDDIO rail dips into this region, the BOR will trip. From the scope shot your provided, the VDDIO rail is even dipping below 2v so your customer shouldn't be surprised the BOR is tripping. If they want to verify it's the BOR that's actually tripping, they can monitor how it takes XRSn to go back high after the VDDIO rail crosses the hysteresis threshold of 35mV.

    By the way, we recommend customers use an external supervisor on the F28035 device.