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TPS3431: TPS3431 SET1 and EN Inputs

Javier Moran
Intellectual 340 points
Part Number: TPS3431

Hello community

I am planning to use TPS3431 in a design. I have a doubt about the behaviour of the EN and SET1 inputs.

If I hold low any of them the WD function will be disabled?. Will WDO output remain in low state if I hold these inputs low?

Best regards!

  • 0
    TI__Genius 9375 points

    Hi Javier,

    I'll explain what happens to the watchdog for both of these inputs, per the datasheet:

    EN: Enable input pin. This pin is internally pulled up to VDD and must be logic high or left floating. When EN goes logic

    low, ENOUT goes logic low and WDI is ignored and WDO remains logic high. When EN goes logic high, ENOUT

    goes high (asserts) after the watchdog reset delay time (tRST). This pin can also be driven with an external pushbutton, transistor, or microcontroller.

    SET1: Logic input. Grounding the SET1 pin disables the watchdog timer. SET1 and CWD select the watchdog timeouts

    EN needs to be logic high/floating to function and SET1 needs to be not grounded for the watchdog to function.

    Thanks,

    Abhinav.

  • 0 in reply to Abhinav.Sharma
    Intellectual 340 points
    Hi Abhinav thanks for your quick answer.
    Excellent. I´ve jus read that I can connect both ENOUT and WDO togheter. I need to implement a function that if an external input is grounded WDO should go low also. If I tie them together with ENOUT a can hold both outputs low when EN is low.
    Thanks again!
  • 0 in reply to Javier Moran
    Intellectual 340 points

    Hello community

    I have an additional question regarding TPS3431. When the WDT goes from disabled to enabled (by either EN or SET1 inputs) does the timer starts from 0?

    Thanks!

     

  • 0 in reply to Javier Moran
    TI__Genius 9375 points
    Javier,

    When the WDT goes from disabled to enabled, it resets and should start from "0". Keep in mind, however, that after SET1 is brought low there is a 150us setup time where the watchdog does not respond to changes on WDI as you can see in section 7.3.2.4 of the datasheet.

    Thanks,
    Abhinav.