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TMS320F280021-Q1: XRSn Pull

Simon Jagla
Expert 7615 points
Part Number: TMS320F280021-Q1

Hi Experts,

A customers design uses a special circuitry to drive the XRSn of the TMS. In the datasheet it is recommended to use a 10k pull up for this pin, however the special circuit does not allow to drive a lot of current. Because of that they are asking if they can increase the pull up to 68k?

Let me know if there are concerns with this or If the reduced pull strength only influencing the EMI robustness.

BR Simon

  • 0
    TI__Mastermind 28275 points

    Hi Simon,

    That should be ok. The restriction is more on the lower end where if the pull-up is too strong, the device might be unable to pull the pin low if needed. On the high end, the pull-up should be strong enough not to give the appearance the pin is floating but i don't think 68k is high enough to end up in this state. 

    You might see longer power up times with the reduced pull-up strenght as it will take longer for the XRSn signal to rise due to the formed RC network.