kahlenberg
Junior Member level 3
Hi,
I have an LiIon battary pack, charger module and a small solar panel. I am charging it with solar energy.
Output of the charger module is directly connected to solar panel (+) and battery (+), that means, there is no constant voltage at output. It varies from 2.5V to 4.2V.
I want to connect a ESP32 module to output and power it. But ESP32 works only 3.0V to 3.6V. That means, I need a circuit that switches the output voltage to ESP32 module, if voltage is above 3.0V. If the voltage is greater than 3.6V it must limit the voltage down to 3.6V.
Voltage threshold can be made with FET transistor and two resistors. I can set the resistor values to switch the FET on, when voltage is greater than 3.0V.
But I don't know how I can limit the voltage when it is above 3.6V. I can use a diode and voltage drop at diode is 0.7V, that means 4.2-0.7=3.6V. It will work but when I connect a diode directly to output, then it will limit voltage always. I need limitation only if voltage is above a certain value.
I have an LiIon battary pack, charger module and a small solar panel. I am charging it with solar energy.
Output of the charger module is directly connected to solar panel (+) and battery (+), that means, there is no constant voltage at output. It varies from 2.5V to 4.2V.
I want to connect a ESP32 module to output and power it. But ESP32 works only 3.0V to 3.6V. That means, I need a circuit that switches the output voltage to ESP32 module, if voltage is above 3.0V. If the voltage is greater than 3.6V it must limit the voltage down to 3.6V.
Voltage threshold can be made with FET transistor and two resistors. I can set the resistor values to switch the FET on, when voltage is greater than 3.0V.
But I don't know how I can limit the voltage when it is above 3.6V. I can use a diode and voltage drop at diode is 0.7V, that means 4.2-0.7=3.6V. It will work but when I connect a diode directly to output, then it will limit voltage always. I need limitation only if voltage is above a certain value.
