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CDCE906 Fail issue

Kai Hsiao
Guru 12675 points
Other Parts Discussed in Thread: CDCE906

Dear Sir

We have a project use CDCE906 to sync display clock

But this project we have 2pcs of CDCE906 can't workable

issue : Provide differential 100MHz clock input to CDCE906 and output provide 30Hz clcok signal (Normal CDCE906 Y0 is 100MHz)

We dump the fail CDCE906's register and find one register can't be wrote ,Just can be read only and the volume is not I want 

Could you kindly give me more idea or experience about this issue ??

BTW. I want to erase the EEPROM's register ,does CDCE906 have H/W method to erase? As I know EEPROM can short with two pins and can be erased strongly

Thanks

 

  • 0
    TI__Expert 5325 points

    Hello Kai,

    the CDCE906 has an EEPROM which can overwritten using the EEWRITE bit in Byte 26.

    You didn't lock the EEPROM with the EELOCK bit in Byte 25 as I can see in your screenshot.

    • Is the config shown in the screenshot the EEPROM content or do you try to overwrite while the system is running?
      • Did you do a lot of test EEPROM writes to these units?
    • Can you share a screenshot of your input signal (VIH, VIL, VID & VIC, duty cycle)?
      • What is the source of the input signal?

    After typically 1000 EEPROM writes you have to expect that the EEPROM might have exceeded its write cycles.

    It seems to me you could omit the write to the Byte 15 as you are not using this output divider anyway when I look at your device config.

    I would recommend to only access registers 0-26 through the SMBUS. There may be test registers outside that range which could trigger unexpected results. This covers command byte values of: 0x80 to 0x9A.

    There is no way to erase the EEPROM physically. You can only overwrite using the SMBUS. Should you have locked the EEPROM, you can only overwrite the registers actively by another SMBUS write.

    Best regards,

    Patrick

  • 0 in reply to Patrick Kammermayer
    Guru 12675 points
    Dear Patrick

    Thanks for your reply

    We verify CDCE906's impedance ,We find some of VCC pins had already short to GND
    But this IC's EEPROM still could be read / write

    We will verify your suggestion and do finally confirm

    Thanks