I am using 2 lithium ion batteries and a buck converter to regulate the voltage at 5v and then power the ESP32. I want to switch off the supply when the the voltage reaches at 5v(from the batteries), as one of the batteries might reach to its lower voltage limit. For this, I used bms, but it didn't do anything as the supply was on but since buck converter doesn't work when input voltage is lower than output voltage the circuit wasn't on.
I tried using TL431 for undervoltage protection(creating the voltage divider) but when connecting to ESP32 voltage drops suddenly .
Please do suggest what can I do regarding this.
ESP32 is a 3.3V device, not a 5V device. Only one battery would be needed, provided that the regulator is low drop-out (by which I mean ~0.2V drop-out).
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I am using pms7003 sensor which requires 5v , so I am giving vcc of the sensor through Vin pin of ESP32. I am lm2596 buck converter.
I am using lm2596 buck converter
Use the ESP32 to monitor the battery voltage through a voltage divider and turn off the LM2596 with the enable pin.
I would not let the input to the LM2596 drop below 6V.
To make it easier to help, please post the wiring diagram for your project.
If you need 5V, it is much easier to use a single LiPo cell with low voltage protection, and a 5V boost converter. That way there is no need for a balancing charger.
Ohk, will try this
I think you might be having issues with the TL431's current draw. Try using a higher value resistor in the voltage divider and consider buffering the output with a MOSFET. Also, double-check your battery selection and consider using a dedicated LVD circuit for better reliability.
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Sorry for the late reply, and yeah there was problem with TL431's current draw.
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