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Original question:

LMK04616: RESETN Recovery Time

LMK04616: RESETN Recovery Time

Harry Ramaker
Prodigy 50 points
Part Number: LMK04616

I have the same issue. I also need to add a delay after I generate a RESETN pulse. We have connected the LMK04616 EVAL board to an VC707 eval board. The power of both boards is up for a long time so the power supplies should be stable. 

When I do the power-up sequence without issue a reset pulse it works fine. When I add a RESETN pulse just before the sequence it does not work. When I add a 100ms delay between the RESETN pulse and the start of the programming sequence it works fine.

I could not find this behaviour in the datasheet.

  • 0
    TI__Mastermind 30040 points

    Hi Harry,

    I did a quick measurement, and found that it takes about 100ms on the EVAL board for a hardware reset to take effect (compared to about 1µs for a software reset). I measured this by observing the state of the OSCout buffer, which automatically begins generating a copy of the OSCin signal after RESETN is asserted. During a hardware reset, most of the LMK04616 internal LDOs are disconnected to minimize power consumption (compared to a software reset, which is self-clearing, so it does not make sense to disable the LDOs). The LDOs have a settling timer tuned to about 100ms, but it's possible that this timer could take longer for marginal PVT cases. I recommend either adding some margin to the initial programming delay (perhaps 150ms total delay), or waiting to confirm an OSCout signal is present before beginning the programming sequence.

    Regards,

  • 0 in reply to Derek Payne
    Prodigy 50 points

    Thanks for the info