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AM2431: Power up timing requirement

Fangjia Zhu
Prodigy 80 points
Part Number: AM2431

Hello,

We were checking the power rails on our project with the AM243x MCU and found the 1.8V rails are on the edge of failing this power up ramp slew rate below:

What is exactly required by the internal ESD devices here? Does it only requires a slew of >100us from 0V to VDDA(Min) of 1.71V? But the descriptions in 7.10.2.1 made it also sound like the slew rate cannot be bigger than 18mV/us for the entire ramp time – in our case the step part of the ramp at the beginning is failing the requirement.

Thanks,

Fang

  • 0
    TI__Expert 4625 points

    Hello Fang,

    I understand how this could be confusing given TI's recommendation in the datasheet. I will contact an internal expert on this matter and to see if a slew >100uS is acceptable despite having a slew rate that exceeds 18mV/us during steps of the ramp. I will provide a response by tomorrow afternoon. 

    Regards,

    Erik

  • 0 in reply to Erik Friedel
    TI__Expert 4625 points

    Hello Fang,

    The requirement from internal ESD devices for slew rate is less than 18mV/us.

    The 100us slew recommendation is based off of this metric: 1.8V / 18mV/us = 100 us. Having a slew greater than 100us but a slew rate > 18mV/us does not satisfy the power supply slew rate requirement.

    Erik