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LMK62I0-100M: internal pull high of OE pin

Ben Kuo
Expert 6715 points
Part Number: LMK62I0-100M

Dear team,

According to datasheet, LMK62i0 have internal pull high.

But we found we need to add external pull high to enable device output. Without external pull high, we cannot get clock output.

Could you help to confirm if external pull high is must to have or not?

Thanks,

Ben

  • 0
    TI__Expert 6140 points

    Hi Ben,

    How many devices has this been tested on? Just one?

    You can see it's a whole product family and the OE behavior should be exactly the same and we haven't had any issues with regards to this particularly. Without external pullup, is the OE pin left floating? Are you certain it's not being pulled low by some other circuitry when not specifically pulled high?

    Regards,

    Amin

  • 0 in reply to Amin Eshraghi
    TI__Expert 6715 points

    Hi Amin,

    Currently we only get one board on hand and cannot get output clock.

    We have double check OE pin voltage level. Without external pull high, OE pin is keep low voltage. (there are no other circuit connect to OE pin)

    Can we keep OE pin floating and enable device?

    Regards,

    Ben

  • 0 in reply to Ben Kuo
    TI__Expert 6140 points

    Hi Ben,

    Just want to make sure I'm understanding correctly, "Without OE high" is the pin left floating or is actually pulled low / grounded?

    For internal pull up to take over, the pin would have to be left floating. There could be the case where the pin isn't pull high but has a path to ground so it's being puled low externally, which if you're measuring low level on the OE pin suggests.

    Either way, is pulling OE high a concern?

    Regards,

    Amin

  • 0 in reply to Amin Eshraghi
    TI__Expert 6715 points

    Hi Amin,

    We have disconnect all trace at OE pin and measure pin voltage is low status. The only way to enable device have to use external pull high.

    Our concern is the test result and datasheet is not align. In datasheet, device have internal pull high and should be enable when OE pin floating.

    But we double check this on different PCB boards and units, floating OE pin cannot enable device.

    Please contact me off-line for more detail. thanks.

    Ben

    benkuo@ti.com

  • 0 in reply to Ben Kuo
    TI__Expert 6140 points

    Will follow up offline, update thread post conclusion.

    Amin