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LMK00804B-Q1: CLK_SEL connection

Kei Kuwahara
Expert 7760 points
Part Number: LMK00804B-Q1

Tool/software:

Hello team,

Can I connect the CLK_SEL pin to the CMOS output via 1kΩ resistor like figure below?

On the datasheet, it says "Clock select input. Typically connected to VDD with an external 1-kΩ pullup. When unused, leave floating", but I don't think I need to pull up to VDD if I am using CMOS output connected to it.

Best Regards,
Kei Kuwahara

Best Regards,
Kei Kuwahara

  • +1
    TI__Genius 9170 points

    Hi Kei,

    You are correct, you should not need to connect to VDD with an external 1-kΩ pullup if you have a CMOS driver inputting the signal to CLK_SEL. So long as the input signal remains high you will be fine.

    Thanks,

    Michael

  • +1
    TI__Mastermind 29362 points

    Hi Kei, 
    CLK_SEL chooses which input you want to use. 
    Whether the LVCMOS_CLK or the differential input. 

    If left floating by default the input being utilized is the differential input. 


    When pulled low the input is LVCMOS. 

    Please either pull High to VDD, to GND or leave floating if not needed. 

    Best regards, 

    Vicente