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# TPS3700: design required and TINA issue

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

• Hi Jean Liao

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