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Multi-sourced, 30 MHz crystal for TMS320F2812

Gary Lynch
Expert 1310 points

Other Parts Discussed in Thread: TMS320F2812

According to the TMS320F2812 Data Manual (SPRS174R, p. 52) I
need to choose the crystal (and accompanying load
capacitors) very carefully to use the internal oscillator:

 "A. TI recommends that customers have the
     resonator/crystal vendor characterize the operation of
     their device with the DSP chip. The resonator/crystal
     vendor has the equipment and expertise to tune the tank
     circuit. The vendor can also advise the customer
     regarding the proper tank component values that will
     ensure start-up and stability over the entire operating
     range."

I found 3 sources that looked like they were compatible,
contacted each of their reps, asking whether they had
qualified my (or any) part number with the F2812. One of
them told me they would do it for $750. The other two didn't
even answer the question.

Has anyone ever identified co-operative sources for these
parts?

(Advance thanks.)

  • 0
    Intellectual 810 points

    750 bucks for a crystal? crystal is not very critical, just follows the reference designed given by Spectrum Digital ezDSP u would know what part u need.

  • 0 in reply to Yu Cai62050
    Expert 1310 points

    1.  The $750 NRE charge is a one-time service fee to
        CHARACTERIZE their crystal to my DSP (as TI recommends
        in their data sheet), not the price of a crystal.

    2.  I have a Rev A ezDsp board and the schematic for Rev C
        of the same board. Spectrum Digital apparently generates
        their clock signal inside an ASIC that drives the JTAG
        interface on that board.

        There is a note on the schematic that infers the F2812
        on my ezDsp is being clocked with the wrong voltage.
        (It appears I bought a prototype board.)

    I have no use for 30 MHz elsewhere on my board and intend to
    use the oscillator built into the F2812. Therefore the
    reference design does not apply.

    If this is not the forum for asking hardware questions about
    the TMS320F2812, could somebody point me to the correct one?

  • 0 in reply to Gary Lynch
    Intellectual 810 points

    i think no matter u want to bypass internal oscillator or not, u always needs an external clock source, either crystal or the other external clock. ezDSP used 30Mhz crystal which is very cheap.

    regarding to the p. 52 of f2812, either internal oscillator or PLL module needs external clock as reference. I don't think u can skip a crystal on board to make this DSP work.

    the JTAG header can directly interface with DSP, the ASIC/FPGA in ezDSP is for parallel port emulator and is not necessary for customized target board with JTAG emulator.