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TMS320F28377D: VDD, VDDA

Tjarco Boerkoel
Expert 1725 points

Hi All,

I'm having a question about the voltage supplies of the TMS320F28377.

Are VDD and VDDA internally connected together or are they different (isolated) supply rails.

best regards,

Tjarco

  • 0
    TI__Guru 60865 points

    Hi Tjarco,

    VDD is actually 1.2V while VDDA is 3.3V. 

    There are a few more 3.3V rails too:

    VDDIO: (I/O supplies)

    VDD3VFL: (Flash supply)

    VDDOSC: Oscillator supply

    I am not sure to what extent these supplies are isolated from each other, but you should tie all the supplies together, with separate decoupling capacitors on each pin, and power up these 3.3V rails together.

  • 0 in reply to Devin Cottier
    Expert 1725 points

    Hi Devin,

    Yes sorry, I mend the VDD3VFL, VDDA, VDDIO and VDDOSC. Is the VDDA a "isolated" supply rails only for analogue subsystem, or are all these 3V3 supplies internally tied together?

  • 0 in reply to Tjarco Boerkoel
    TI__Expert 4810 points

    Tjarco,

    Yes, these supplies are internally isolated from each other.  This is done primarily for internal noise isolation between the supplies. 

    What is the reason behind the question?  Are you seeing issues or just curiosity?

    Best regards,
    Jason

  • 0 in reply to Jason Whiles
    Expert 1725 points

    Hi Jason,


    No I'm having separated power supplies for analogue and digital 3V3, but if they we tied together internally then the two supplies would result in currents through the VDD3VFL, VDDA, VDDIO and VDDOSC pins. So I'm glad to hear they're internally isolated.

    Thank you!