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TMS320F28069M: Internal zero pin oscillator and CAN clock, UART clock

Gunter Schmer
Genius 14352 points

Part Number: TMS320F28069M

Hi,

the F28069M has an option to use the internal oscillator (zero pin) vs an external oscillator.We were planning on using the zero pin oscillator but wanted to know whether there are any impacts on the clock speed and jitter requirements for a CAN interface.

Also we were wondering if there are any impacts on the clock speed requirement and jitter for a UART as well. The data sheet has a graph with clock speed over temperature.

Thanks!

--Gunter

  • 0
    TI__Guru* 82350 points
    Gunter,
    My general experience is that UART had a clock tolerace of +/-3% and CAN has a clock tolerace of +/-1% . Keep in mind this the total signal chain allowable error, so the F2806x may not be the only component in the equation.

    For CAN, specifically, I beleive you will need to look at an external X-tal/oscillator since with any nominal temp change the F2806x will consume the 1% on its own and there is some variability on the center frequency even at 30C.

    If there are different board configs for UART vs CAN, then I think the UART is more tenable with the zero pin, but if all the boards are the same and must support CAN and UART then you'll be using an external X-tal anyway.

    Let me know if I can be of more help.

    Best,
    Matthew