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TPS3700: design required and TINA issue

Jieying Liao
Prodigy 20 points
Part Number: TPS3700

Hi team

    my customer has a design requirement via TPS3700

   The input  voltage (Vmon) is used to supply power to MCU, normally around 3.3V, so they need to design a voltage monitoring and protection circuit now:

          1. When the input voltage (Vmon) is 3.6V ~ 4.7V, a falling edge signal is output to reset the MCU reset pin (RST).

          2. When the input voltage (Vmon) is greater than 4.7V, a low-level signal is output to turn off the DCDC supplying power to the chip.

       

In this design, I used the resistance calculation software on the page of tps3700. After I input the required voltage, I get the resistance(R1,R2,R3) of the peripheral circuit.

 

Then I use Tina to build the simulation circuit. Through simulation, it is found that the result is not consistent with the theory. OUTA does not have high-level jump when Vmon is greater than 3.6V.

1. Could you please help me analysis that result ?

2. Could you please give me a design based on my customer ' s requirement and help me calculate the R1,R2,R3 and Rp value? 

Best regards

Jean Liao

jean-liao@ti.com

  • 0
    TI__Genius 10951 points

    Hi Jean Liao 


    My understanding for your problem is as follow - 

    Normal operating for the MCU is 3.3V. 

    When the voltage goes above 3.6V , user wants to turn off the supply by sending a negative edge. 

    When the voltage goes above 4.7V , user wants to turn off the DC-DC power supply. 

    In this case you should select 

    VMON = 4V (some intermediate voltage)

    VUV = 3.6V

    VOV = 4.7V and calculate the resistance values.

    RPU = 50k for boath out A and OUT B

    Connect an inverter at OUT A pin and give it to MCU and give OUT B supply directly to MCU. It will work. 

    Regards

    Trailokya