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TPS3430-Q1: special application

li xuefeng
Prodigy 50 points
Part Number: TPS3430-Q1

Tool/software:

Hello teams,

       We use TPS3430-Q1 in our design ,we want to reset Watchdog， the design like this picture. is it OK? 

The WDO is high when the VDD1 and VDD2 is low, is it right?

  • 0
    TI__Genius 11520 points

    Hi Li,

    The WDO will be in a high impedance state while the supply voltage is below VDD(min) = 1.6V. 

    In your schematic the WDO is pulled up to the same VCC as the VDD, so if the VDD is low the WDO will be at that same low level.

    If you want the WDO net to be high while the VDD is low you will need to have the WDO pulled up to a separate rail that is already powered on while VDD is low. 

    Thanks,
    Joshua

  • 0 in reply to Joshua Garcia
    Prodigy 50 points

    Hi Joshua,

        Thanks for your feedback,Yes  I will use a separate rail. 

        You can see a resistor(100Ω) between VCC and VDD, can the TPS3430-Q1 work well?  What is the maximum resistance that can be used？

  • 0 in reply to li xuefeng
    TI__Genius 11520 points

    Hi Li,

    Assuming the current leakage from the mosfet is minimal, there is no concern to have a 100ohm resistor here on the VDD. The supply current for this device to operate properly is 19uA max, and given that VDD(min) = 1.6V, 1.6V/100ohms = ~16mA or greater will be provided to the VDD.

    Thanks,
    Joshua

  • 0 in reply to Joshua Garcia
    Prodigy 50 points

    Hi Joshua，

         In my  design ,I want to reset the TPS3430-Q1,so I will make mosfet on/off to reset TPS3430-Q1,so I need to use a resistor in series. The supply current for this device to operate properly is 19uA max, so i think a 100Ω or bigger resistor in series is ok , TPS3430-Q1 can work well?

  • +1 in reply to li xuefeng
    TI__Genius 11520 points

    Hi Li,

    There should be no concern, the TPS3430-Q1 can work well. However, given you are looking to have an enable/disable function of the watchdog and this is a new design I would recommend the TPS3436-Q1 this device has a built in watchdog enable pin that can remove the need for the external FET.

    I sent over an email to get more details here.

    Thanks,
    Joshua