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TL7712A: Design for power failure detection into micro controller

Part Number: TL7712A
Other Parts Discussed in Thread: TL7705A, TPS3710

I am new to the thread community and appreciate any help in advance.

I am designing a circuit to detect a power failure to properly shutdown a raspberry pi controller running on linux OS. I am using a 12V power supply and regulating 12V down to 5V to power the controller. I want to use the TL7712A to detect the voltage drop at 10.8V when the power supply fails or power is lost. 

My question is, what is the output voltage of the RESET and nRESET pins? I am needing a voltage of 3.3V to input the controller. A 5v signal may damage the pins on the controller. This may be a simple question but I could not find anything in the datasheet explaining the Vhigh and Vlow of the RESET and nRESET pins for the TL7712A "12v" supervisor.

The graphs only show the Vhigh and Vlow of the RESET and nRESET pins for the TL7705A "5v" supervisor. 

May need transistor after RESET outputs? Any suggestions?

  • Ivan,

    For TL7712A, the /RESET output voltage will be limited to the voltage that connects to the pull-up resistor since this output is open drain. For RESET, the voltage will be limited to VDD since this is also open drain but uses a PMOS and a pull-down resistor.

    You can also check out TPS3710 as a very simple wide Vin voltage detector that allows you to pull-up to other voltages independent of VDD.

    Please let me know if you have any other questions. Thanks!

    -Michael
  • Michael,

    The TPS3710 is exactly what I was looking for. Thanks for the guidance!

    -Ivan