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Original question:

CDC3RL02: The specification of Master clock input (MCLK_IN)

CDC3RL02: The specification of Master clock input (MCLK_IN)

May San Loo
Prodigy 80 points
Part Number: CDC3RL02

the previous post stated that the CDC3RL02 can take in an AC-coupled signal. In this case, what is the expected clock output range? We do observed negative voltage at clock output with AC coupled clock input. 

However, section 7.3 in the datasheet shows that the CLK_OUT at min 0V. 

  • 0
    TI__Genius 16845 points
    It may have been incorrect to assume that the device can accept an AC-coupled input. Can you apply a DC-coupled input CDC3RL02 and report what you observe at the output?

    Kind regards,
    Lane
  • 0 in reply to Lane Boyd
    Prodigy 80 points
    DC coupled input signal into MCLK_IN - we do not observed any abnormality.
    AC coupled input signal into MCLK_IN (swing between -0.58V to +0.51V) - we did observe output swing below 0V(swing between -0.9 to +0.9V) .

    From datasheet,-0.3V is the absolute minimum input.

    But from your previous thread, you say that :
    "You can apply an AC-coupled signal to MCLK_IN. The AC-coupling capacitor is included on the MCLK_IN pin as indicated in Figure 11, therefore CDC3RL02 will also accept a DC-coupled input."

    However, you replied on Sep4, 2018:
    "It may have been incorrect to assume that the device can accept an AC-coupled input. Can you apply a DC-coupled input CDC3RL02 and report what you observe at the output? "

    Please help to confirm.
  • 0 in reply to May San Loo
    TI__Genius 16845 points
    Based on the results of your experiment it seems that my previous reply was incorrect and AC-coupled inputs should not be used with this device. If you are observing negative voltage at the output then there is a potential for performance degradation or damage to the device.

    Unfortunately I am not the expert on this part and my previous reply was based on my limited experience with the device. After further investigation, we don't have any data suggesting that this device can accept an AC-coupled input.

    Kind regards,
    Lane
  • 0 in reply to Lane Boyd
    Prodigy 40 points
    I thought this technical forum is suppose to guide us with accurate information but your replies seems otherwise.


    I hope those expert and PIC of the product should reply the related question because inaccurate answer can lead to design flaw.