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TPS3823: When using TPS3823-33DBVR to replace competitor CAT823STDI-GT3, after running a period of time, it appear a problem

Eggsy Pang
Expert 4985 points
Part Number: TPS3823

Hi Team,

      Customers feedback that when using TPS3823-33DBVR  to replace competitor CAT823STDI-GT3,  after running a period of time, maybe after one hour or maybe half of hour, it appear below problem.

The problem is that the reset pin output low logic and cause the system reset. We test the VCC keep 3.3V, WDI disable, MR keep high. It should not reset. We don't know why.

      Below is SCH. CAT823STDI-GT3 is stable on their product. Do you have any suggestions?

  • 0
    TI__Genius 12630 points
    Hi Eggsy,

    There are two possible issues,

    1) If WDI is not high impedance, this will trigger a reset. WDI must be high impedance to disable the watchdog. In the schematic above, the "Y" pin is connected to a voltage divider and looks like 1.185V is constant to WDI pin which will trigger a reset.

    2) If not using A version, when WDI is received (a rising or falling edge) while /RESET is active and logic low, then /RESET will remain latched logic low. Please confirm if you are using the A version or not.

    Please check the logic for WDI and be sure that the " Y " signal is high impedance into WDI when watchdog needs to be disabled.

    Question 1: Why do you use resistor divider R47 and R52 at the "Y" output of the buffer? I don't think this will work. Please remove R47 and R52 so when the buffer "/OE" is low, the "Y" output will be high impedance, and WDI will not cause reset.

    Please let me know if this works for you.

    -Michael