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LMK03318: No output after working for a while

Part Number: LMK03318

Hi team,

The output may disappear after working for a while. Sometimes it always keeps OK.

The output becomes OK after reset the power supply.

Any suggestion for this?

Robin

  • Hello Robin,

    Can you tell me more about what happens? For example is this a programmed EEPROM configuration that you power-up and automatically get output clocks? Then the clock stops, you do a reset and the clock operate again. After the reset of power supply, might the clocks output fail again?

    What is the clock output format?

    Can you share the device programming?

    73,
    Timothy
  • Please check:
    1. Check PLL is locked (PLL lock status can be indicated on STATUS output pins). Loss of PLL Lock cause the outputs to be muted.
    2. Check GPIO0 is pulled high. When GPIO0 is low, it could cause the outputs to be held in SYNC state.

    If you would like TI Clocking Applications to privately review the customer's schematics and GUI configuration file, please send the files to clock_support@list.ti.com and close this thread.

    Alan
  • In reply to Alan O:

    Hello Alan:
    This is BOE . I have some question about LMK03318:
    1. I checked the PLL, the P_LOL signal status lamp flickered. The output of LMK03318 will disappear after running for a period of time. I want to ask how to set it up so that the PLL can be locked consistently?
    2. I used the second clock input, 100MHz differential input and 270MHz output. How to set it correctly?
    3. The GPIO0 is pulled high.

    Thanks.

    Bao
  • In reply to Timothy T:

    Hello Timothy:
    This is BOE .
    1. When the EEPROM is programmed, the LMK03318 can get output clocks.
    2. The output becomes OK after reset the power supply. After the reset of power supply, the clocks output will fail again .
    3. The clock output is differential output.
    4. I used the second clock input, 100MHz differential input and 270MHz output.
    5. I think the problem is that PLL is not locked. Do you know how to set it correctly?

    Thanks.

    Bao
  • In reply to Alan O:

    Hello Alan:

    This is BOE.

     I used the second clock input, 100MHz differential input and 270MHz output. After running for a period of time, the LMK03318 output is 230Mhz instead of 270Mhz.

     I checked the PLL, the P_LOL signal status lamp flickered. When the P_LOL signal status lamp is always on, the output of LMK03318 changes from 270 Mhz to 230 Mhz.

    Here is my  setup interface, Could you tell me where the settings are incorrect?

    Looking forward to your reply.

     

    Bao.

  • In reply to user4949375:

    I suggest the following changes, based on your frequency plan:

    PLL page:

    • PLL R divider = 1
    • PLL N divider = 54
    • PFD frequency = 100 MHz
    • VCO frequency = 5400 MHz

    On Inputs/PLL page...

    PLL block:

    • PLL Order = Integer
    • Dither = Disabled
    • Stretch = 200 pF
    • R3 mode = Int-PLL
    • R2 = 535 ohms
    • R3 = 518 ohms
    • C1 = 55 pF
    • C3 = 35 pF

    External (onboard) C2 cap = 3300 pF

    Input timers:

    • PLL Closed Loop Wait = 0.3 ms
    • PLL VCO Wait = 0.4 ms

    Input detectors:

    • Ref Detector = Enabled
    • PRI & SEC Diff Detect Level = 300 mVpp swing

    SECREF input:

    • 100ohm Diff Term enabled

    Regards,
    Alan

  • In reply to Alan O:

    Hello Alan:

    According to the settings you recommended, the P_LOL lamp still flickers and the LMK03318 will still turn 230MHz after running for a period of time.

    Do you know how to solve this problem?

    Looking forward to your reply.

    Bao.

  • In reply to user4949375:

    Is your reference input a stable clock source, like a crystal oscillator, or is it a noisy recovered clock?  It should be stable in both frequency and amplitude.

    Also, did you try triggering a soft reset after writing all registers, so the PLL/VCO gets re-calibrated (after the reference input is stable)?

    Alan

  • In reply to Alan O:

    Hello Alan:

    I set the Charge Pump Gain to 0.4mA, the LMK03318 outputs is 270Mhz.Now the LMK03318 can work properly.

    Thank you very much for your help.

    Bao.