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TMS320F280049: Questions regarding BOR on F280049

Sheldon He
Expert 8585 points
Part Number: TMS320F280049

Hi expert,

I am new to BOR feature on F280049 device and can't get much information from datasheet and google, this feature seems barely mentioned by engineers.

In the datasheet "Figure 5-1. Supply Voltages", we divided supplt voltage into three parts and the middle one is call a "BOR Guard Band". Could the "BOR Guard Band" be disabled or enabled by registers?

As for "Internal BOR Threshold" part, please help me check if my understanding is right or not: If BOR is enabled, when VDDIO drops into "Internal BOR Threshold" area, device will trigger a "POR reset source" and get reset. But if BOR is disabled the device can work normally at VDDIO as low as 2.8V but may cause uncertainty when VDDIO drop even lower, for example 2.7V.

Thanks

Sheldon

Internal BOR Threshold

  • 0
    TI__Mastermind 28275 points

    Hi Sheldon,

    All the information the user needs to know about the BOR is provided in the datasheet.

    The Supply Voltages figure shows the various BOR regions.

    Region 1 (2.81V to 3.0V) [Internal BOR Threshold] : This is the internal BOR trip region. This means if your supply falls within this range, the internal BOR will trip and reset the device.

    Region 2 (3.0V to 3.1V) [BOR Guard Band] : This is the user margin region. The BOR will not trip if your supply falls within this range. TI recommends that the user bakes at least this margin into their power supply design to account for supply noise and load transient events. Essentially this means instead of choosing a supply that has a minimum of 3.0V(this is our maximum BOR trip level), it's recommended to choose a supply that has a minimum of 3.1V. This way supply load transients and noise don't trip the BOR.  

    2.8V is the minimum recommended operating voltage. The internal BOR will trip before the voltage gets to 2.8V. However if you disable the internal BOR and are using an external supervisor, you will need to make sure that the supervisor trips before the voltage drops to 2.8V.

    Let us know if it's not clear.

  • 0 in reply to Frank Ankapong
    TI__Expert 8585 points

    Precise answer. Thanks