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LMK03200: The OSC pin of the LMK03200 is delayed 60sec

user597158
Prodigy 125 points
Part Number: LMK03200
Other Parts Discussed in Thread: LMK00308

Hello,

we adopted LMK03200 for our new product.
OSCin pin of LMK03200 is connected to CLKoutA0 pin of LMK00308(front-end).
CLKi pin of LMK00308 is connected from other product(called JIGU).
Now, we are debugging this product.

At this product, when power up, CLKi pin of LMK00308 is stable "L" level.
Because JIGU need about 60sec to start up.
After start up JIGU, CLKi pin of LMK00308 is added 20MHz signal.

After 20 MHz is added, we reset the device by the "RESET" bit of bit-31 of register0(R0) of LMK03200, and set other register of LMK03200.
However, CLKout pin of LMK03200 output 4MHz or 11MHz or other frequency. (not stable)

If we power up LMK00308/LMK03200 after 60sec from the start up of JIGU, the output of the CLKout pin of LMK03200 will be purposeful 10MHz.

From these results, the LMK03200 considers that it is necessary to apply a signal to OSCin at power-on.
But our system does not meet this requirement.
Do you have any solutions?

Thank you for your time and consideration.

Best Regards,
Toshiyuki Maekawa, Advanet Inc.

  • 0
    TI__Expert 4415 points

    Hi Toshiyuki-san,

    It sounds like the PLL is not locking. Since the device does not have a valid input frequency it is unable to perform a correct frequency calibration, which happens at startup.

    The solution is to run the frequency calibration again after the input clock is present. See page 19 of the datasheet: "For the frequency calibration routine to work properly OSCin must be driven by a valid signal when R15 is programmed. Any changes to the PLL_R divider or OSCin require R15 to be programmed again while 0_DELAY_MODE = 0 to activate the frequency calibration routine." By re-programming R15, the device should run frequency calibration again and allow the PLL to lock.

    Regards,

    -Tim

  • 0 in reply to Tim Chao Li
    Prodigy 125 points

    Hello Tim-san,

    We are grateful for your deliberate resoponse to our request.

    We could solve the problem by following your advice to executing the procedure.
    We really appreciate your help.

    Thank you for your time and consideration.

    Best Regards,
    Toshiyuki Maekawa, Advanet Inc.