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Supervisor TLV803S lock-up

Ken DeGrave
Prodigy 40 points

Dear Sirs:

I have a condition at 95 degree C ambient where a TLV803S is connected to the reset pin 2 of a Freescale MC5684565 uC with a 10K pull up to 3.3v and a 0.1uF pull down to ground which some times lock to a 600mV level.

If I bring the temperature to room it still is at this level.

If I remove power and re-energize it still stays at this level.

If the reset line is shorted to ground and opened, it stays at this level.

If the reset line is shorted to 3.3 volts and opened, the reset line now operates normally.

At this moment in time we do not know what triggers this condition.

We do not know if it is the supervisor or the uC.

We are currently doing non-evasive testing before we can start physically altering the node.

Dose anyone have any ideas what this may be?

Ken DeGrave

  • 0
    TI__Guru 55940 points

    Hi Ken,

    I know you said that you are currently taking data to try to help debug, but when you say that it sometimes gets stuck at 600mV, do you know /RESET should be transitioning in the low to high direction, high to low direction, or does it occur both directions?

    When you state that reset is shorted to 3.3V, is 3.3V VDD?  What is the pullup voltage?

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Prodigy 40 points
    Ryan,

    The POR assert voltage for the uC is typ. 2.0 volt (high to low).
    The POR release voltage for the uC is typ 2.7 volt (low to high).

    The 3.3V is Vdd and the pullup voltage.

    We are right now taking a fresh new controller and applying a voltage using a variable power supply to look at how the reset operates.

    Ken