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TMS320F28069: XRS pin of the CPU

Haggai Daum
Prodigy 80 points
Part Number: TMS320F28069

Hi

In my CPU design, pin XRS is left unconnected. (80 pin package, pin number 9)

I do not use this pin to assert input external RESET by HW.

I do not use the watchdog reset output either.

My question is: May I leave this pin not connected, or should I follow the statement in Datasheet (page 15) which states to place a Pull-Up resistor (and a possible cap)?

If  pull up is required, then I must re-layout my board, or add quite a complicated "stitch" , manually , by soldering an appropriate resistor on the PCB.

  • 0
    TI__Guru* 95315 points

    It depends on the noise level in the circuit. The –XRS pin does have an internal pull-up, but it is not a very strong PU (the strength of this PU is provided in the datasheet). This is the reason the datasheet recommends an external PU for better noise immunity.