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AM2634-Q1: Please help check this power sequence

Will Gao
Intellectual 2335 points

Part Number: AM2634-Q1

Hi BU, 

In my customer's board, the following power up sequence is found. 

The green signal is PORz, blue signal is WARMRSTz, yellow signal is 1.2V VDD, and the pink signal is the crystal oscillator. 

From the waveform, it seems that the t_WARMRSTz not meet the AM263x power-on sequencing requirement in Datasheet: 

Please help check if this is fine or not. 

From my understanding, the WARMRSTz pin is de-asserted by device but not peripheral circuit during power-up phase. So it will be ok? 

BR, 

Will 

  • +1
    TI__Mastermind 18500 points

    Hi Will, 

    On the AM263x devices, the WARMRESETz pin is a reset status output by default. So this is not part of the required power on reset inputs to the devices, but should be used to check if reset has propagated through the device. Likewise, the XTAL oscillation will start up as a function of PORz and power being applied correctly. 

    PORz, 1.2V power and 3.3V power are the only inputs that need to be sequenced. From the table/diagram in the datasheet, the ONLY requirement is that 1.2V and 3.3V are at their nominal voltage (see operating conditions table) prior to PORz being brought low to high (GND to 3.3V). 

    To evaluate if the power on sequence is valid, you need an oscilloscope shot of the PORz, 1.2V and 3.3V rails. PORz should not be brought high prior to 1.2V and 3.3V being valid. 

    Thank you,

    -Randy

  • 0 in reply to Randy Rosales
    TI__Intellectual 2335 points

    Hi Randy, 

    Understood, will let customer to check the PORz, 1.2V and 3.3V rails.

    Thanks, 

    Will