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TPS3840: Does VDD drop to Vpor damage the TPS3840 or any other risk ?

dimitry chen
Expert 1065 points
Part Number: TPS3840

Hi 

TPS3840 in my system have VDD drop issue durring some voltage level.

But thershold level VDD is stable, and reset output is functional.

And we don't plan to change resistor value. and the system design don't care " Vpor status." 

is any other risk for this design ?

and I already check the FAQ, I can't find the suitable anser.

[FAQ] TPS3840: resistor divider for sensing wide input voltages

One thing to note, during start-up the TPS3840 will have a slight in-rush current that causes a voltage drop across R1.  The in-rush current usually occurs for tens of microseconds.  Depending on the size of R1, too large of a resistor may cause a large voltage drop at the input of VDD.  If the voltage drop causes the input of VDD to drop below the VPOR spec (950mV for open-drain output option) the TPS3840 will turn off and not allow the output (/RESET) to deassert.  It is suggested that R1 should not be larger than 20Kohms and when using a resistor divider a 1uF capacitor (C1) should be placed at the VDD input to reduce the voltage drop seen at VDD."
  • 0
    TI__Expert 5210 points

    Hi Dimitry, 

    Thanks for your question. I just need more information on your design. 

    - What is the voltage in the monitored rail? 

    - How much drop you are experiencing in the VDD? 

    - What is your resistor values?

    Best,

    Sila Atalar