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[FAQ] AM6442: RESET circuit Review for AM6442

Jack
Mastermind 9145 points
Part Number: AM6442

Hi

There's a question about RESET circuit. Please answer to question.

1. Is there any problem that is expected when simplified with POWER-ON and Cold RESET as above circuit?

Thanks.

  • +1
    TI__Guru* 86820 points

    This is not adequate for MCU_PORz.  Please review the reset section 7.10.3.1 and figure 7-3 of the datasheet.  MCU_PORz should be low throughout the power up sequencing and remain low for 9.5ms.  

    Regards,

    James

  • 0 in reply to JJD
    Mastermind 9145 points

    Hi JJD

    Thanks for your kind answer.

  • 0 in reply to JJD
    Prodigy 130 points

    HI JJD

    I have a further question.
    1. Is it a problem because the RC value in the picture above is Reset time=1ms? (If 10Kohm ->100Kohm, 100nF ->220nF is changed and the reset time = 20ms, is it appropriate?)
    2. Is the reset circuit using RC inappropriate?

    Thanks for your kind answer

  • +1 in reply to ho sung moon
    TI__Guru* 86820 points

    Yes, there are several requirements outlined in the datasheet for MCU_PORz.  The signal needs to be low throughout the power on sequencing and remain low for some time after all power supplies are stable, as detailed in figure 7-3 in the datasheet.  Typically, this signal is a delayed output of some power good circuitry from a PMIC or voltage supervisor (you can see an example of this in the GP EVM).   There is also input slew rate requirement which the RC circuit may not be able to meet across temp.

    Regards,

    James

  • 0 in reply to JJD
    Prodigy 130 points

    Hi JJD

    Thanks for your kind answer.