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AWR6843ISK: Purpose of Load switch for delaying 3.3V to xWR6843

Jack
Mastermind 9145 points
Part Number: AWR6843ISK

Hi Ti

There's a question that customer wants to clarify.

Could you please let us know why we need the load switch circuit for delaying 3.3V.

Are you just trying to comply with the Power Up sequence especially for VIOIN ramping timing?

Thanks.

Regards, 
Jack

  • 0
    TI__Mastermind 31680 points

    Hello Jack, 

    I've forwarded your concern to a hardware expert. Please expect a response before the end of this week. 

    Regards,

    Ishita

  • 0 in reply to Ishita Kochar
    Genius 3320 points

    Hi Ishita,

    One more thing, I'd like to ask you about the min. and max. timing specification for delaying VIOIN(3.3V) to xWR6843. Please let me know.

    Regards,

  • 0 in reply to Jeffrey Chung1
    TI__Mastermind 30755 points

    Hello Jack,

    The load switch is designed to delay the AWR 3.3V supply from coming up until after the AWR 1.8V supply. If the AWR 3.3V supply comes up first, this can create a glitch on the MMIC GPIO pins.

    There is one error in the schematic. The NRST should also be delayed by the load switch. This needs to be fixed in a future revision. In the current schematic, the NRST is not connected to the load switch output, which is incorrect as this violates the timing diagram you have provided above. NRST should only come up after the MMIC supplies are stable.

    There is no min/max timing for the delay of the 3.3V supply. It can come up anytime relative to the other MMIC supplies and it will not cause any damage to the device, but you may see a glitch as mentioned above if it comes up before the 1.8V supply. The only requirement is that all supplies are stable for a few milliseconds before NRST is released. 

    Regards,

    Adrian