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CC2564MODN fast clock questions

Engineer1
Intellectual 660 points

1) How does the CC2564B know that the clock in use is 38.4 MHz instead of 26 MHz?

2) What is the aging rate of the 38.4 MHz crystal in PPM/year?

3) What is the frequency change over temperature of the 38.4 MHz crystal over -20 to +70 °C in +/- PPM?

4) What is the initial accuracy of the 38.4 MHz crystal (at 25 °C) in +/- PPM?

5) If programming the RF to CW at 2402 MHz using HCI_VS_DRPb_Tester_Con_TX(0xFD84), is the "Test Parameter" such as "PN9", "all 0", etc., ignored (since CW is the absence of modulation)?

6) If programming the RF to CW at 2402 MHz using HCI_VS_DRPb_Tester_Con_TX(0xFD84), if the 38.4 MHz crystal were exactly on frequency (38.40000000 MHz), would the RF frequency be precisely 2402.000000 MHz?  If not, what would be the precise frequency?  (knowing the precise frequency would be one method of indirectly measuring accuracy of the 38.4 MHz fast clock)

  • 0
    TI__Mastermind 32615 points
    Hi,

    Let me check it internally and get back to you on this
  • 0
    TI__Mastermind 23565 points

    Hi,

    Please find our comments embedded inline below.

    1) How does the CC2564B know that the clock in use is 38.4 MHz instead of 26 MHz?

    [MS]: There is an internal mechanism to the chipmto detect the frequency. No user interaction is required.

    2) What is the aging rate of the 38.4 MHz crystal in PPM/year?

    [MS]: It is +/-3ppm in 7 years.

    3) What is the frequency change over temperature of the 38.4 MHz crystal over -20 to +70 °C in +/- PPM?

    [MS]: It is +/-10ppm.

    4) What is the initial accuracy of the 38.4 MHz crystal (at 25 °C) in +/- PPM?

    [MS]: It is +/-7ppm.

    5) If programming the RF to CW at 2402 MHz using HCI_VS_DRPb_Tester_Con_TX(0xFD84), is the "Test Parameter" such as "PN9", "all 0", etc., ignored (since CW is the absence of modulation)?

    [MS]: Yes, CW (continues wave) ignores such parameteres.

    6) If programming the RF to CW at 2402 MHz using HCI_VS_DRPb_Tester_Con_TX(0xFD84), if the 38.4 MHz crystal were exactly on frequency (38.40000000 MHz), would the RF frequency be precisely 2402.000000 MHz?  If not, what would be the precise frequency?  (knowing the precise frequency would be one method of indirectly measuring accuracy of the 38.4 MHz fast clock)

    [MS]: Please refer to tables 4.5.4.1.4 and 4.5.4.1.5 for frequency drift and stability specs . http://www.ti.com/product/CC2564MODN/datasheet/specifications#SWAS0139710 and http://www.ti.com/product/CC2564MODN/datasheet/specifications#SWAS013875

    Regards,

    Miguel S.

  • 0 in reply to Miguel
    Intellectual 660 points
    Thanks Miguel, but you misinterpreted my question #6. Let me re-phrase. If the fast clock crystal were PRECISELY 38.400000 MHz, what would be the precise transmit CW frequency if 2402 MHz is the intended frequency? Would it be 2402.000000 MHz, or would the closest synthesizable frequency be slightly different from 2402.000000 MHz? Since I don't know how the internal synthesizer works, I cannot tell what the relationship is between the fast clock and carrier frequency. We need to know this if we are to use a particular transmit CW frequency as a measure of the fast clock frequency accuracy. I don't care if the closest synthesizable frequency is not precisely 2402 MHz, I just need to know precisely what it should be if the fast clock is precisely 38.4 MHz.
  • 0 in reply to Engineer1
    TI__Mastermind 23565 points

    Hi,

    You should consider it to be exactly 2402 MHz.

    ~Miguel

  • 0 in reply to Miguel
    Intellectual 660 points
    Thanks, this answers all my questions.