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TMS320F28388D: One question to power sequencing.

Luke Chen
Expert 5090 points
Part Number: TMS320F28388D

Hi champs,

In the schematic of F28388D controlCARD, we set VDDIO(+3.3V) ramps up before VDD (+1.2V) does, but according to TRM, it seems that we don't need to take care of power sequencing of +3.3V and +1.2V.

So, does F2838x need power sequence? Is it okay if +3.3V and +1.2V be powered up simultaneously? Is it safer if we power up VDDIO first and this will make sure VDD keep no more than 0.3V above VDDIO?

Regards,

Luke

  • 0
    TI__Genius 15385 points

    Hi Luke,

    Yes, F2838x needs power sequencing and what is being done is the proper power sequencing, ramping VDDIO first to make sure VDD keep no more than 0.3V above VDDIO.

    Can you please point me to which section in TRM mentions no power sequencing required, so that we can correct that. Please refer datasheet for power sequencing requirements.

    Best Regards,

    Nirav

  • 0 in reply to Nirav Ginwala
    TI__Expert 5090 points

    Nirav,

    In F2838x datasheet Power Sequencing section, it just say VDD Requirements: During the supply ramp, VDD should be kept no more than 0.3 V above VDDIO. This doesn't mean VDDIO should ramping first and will confuse customers.

    Regarding F2837x, F2807x and F280049, we should power on VDD and VDDIO, VDDOSC simultaneously, is this correct please?

    Customers usually ask for timing diagram of power sequencing, do we plan to have the power timing diagram in next revision of datasheet?

    Regards,

    Luke

  • 0 in reply to Luke Chen
    TI__Genius 15385 points

    Hi Luke,

    Yes, you can ramp VDDIO and VDD simultaneously also as long as VDD does not exceed more than 0.3V above VDDIO.

    Yes, we do plan to have the power timing diagram updated, I agree our datasheet currently is little confusing.

    Best Regards,

    Nirav