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SM320F28335-EP: powerup

Ross Atkinson
Prodigy 60 points

Part Number: SM320F28335-EP
Other Parts Discussed in Thread: TPS3805H33

Hi,

in section 6.8 it states, but i have an voltage of 1.3v on an analogue pin 41 of the device, will this cause any issues? Also I have a pushpull reset device then a 1k resistor on the reset pin would this also be an issue as it my slug the speed of the reset. I know this should be ideally an OD device, but my 1k reset should limit the current?

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  • 0
    TI__Mastermind 20951 points

    Hi Ross,

    Are you simply using the analog pin for voltage reading or is it also connected to a comparator? We have seen instance where the presence of a non-grounded voltage skews the CMPSS module, but haven't seen issues with it affecting the actual voltage reading

    For the XRSn, that should be fine. The concern is more on the magnitude on the capacitor added to the reset pin as that has a greater affect on delaying the ability for the device to pull into reset

    Regards,

    Peter

  • 0
    Prodigy 60 points

    Hi Peter

    yes the analog pin is just measuring voltage.

    The reset signal to the device xrs pin comes from a TPS3805h33 which monitors the core voltage and 3.3v. This is a pushpull device. A series 1k resistor is in line to limit current. we are investigating an issue where we are getting startup errors on some processors. and would like to eliminate this as a cause. Note that we check the temp with the lowest temp at -55c.

    regards

    Ross

  • 0 in reply to Ross Atkinson
    TI__Mastermind 20951 points

    Hi Ross,

    This could be the cause of your startup error depending on what peripherals are used during startup. Like I mentioned, this mainly could impact the CMPSS at least from our testing and previous interactions with other engineers, but ADC could also be impacted, for example if you perform some offset calculation with reliance on ADC readings

    Regards,

    Peter