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TMS320F280038C-Q1: Internal reference output

SY Yoon
Genius 3380 points
Part Number: TMS320F280038C-Q1

Hi, C2000 team,

I want to use the 1.65V internal reference voltage as the reference input of the external opamp.

What pin is the reference voltage output port?

Can I use the VREFHI pin as a voltage source for external devices in internal reference mode? 

  • 0
    TI__Mastermind 34565 points

    Hi SY,

    The internal reference voltage comes out of the VREFHI pin and the primary reason why this is the case is that the internal reference voltage has to be filtered by a bulk cap (2.2uF) which is impractical to put inside the chip due to area requirements.  The internal reference voltage really should not be used for any other purpose other than a reference to the on-chip ADC.  Is the intent to use the 1.65V as a common mode reference ot VREF/2 for some other external circuit support?

    Best regards,

    Joseph

  • 0 in reply to Joseph Casuga
    Genius 3380 points

    Hi Joseph,

    Yes, I need 1.65V power for OpAmps.

    So instead of using the external voltage reference IC, I want to use the internal reference to reduce cost.

  • +1 in reply to SY Yoon
    TI__Mastermind 34565 points

    Hi SY,

    You cannot use the 1.65V directly to supply an external circuit since any noise on the VREFHI line would distort the ADC conversions.  If you need to use it as an external reference though, you may be able to do that but ensure that it will be connected on a high impedance buffered circuit that should not draw varying current.

    Regards,

    Joseph