Help with Li-ion Power and Vext Control on ESP32-C3 PCB Design

Question

I am currently designing a PCB based on the ESP32-C3, and I need help integrating a Li-ion cell for power management and controlling the Vext pin for switching between external and battery power. I am a bit unsure how to properly design the circuitry for:

1- Safely charging the Li-ion cell while using the ESP32-C3.

2- Managing power switching between the cell and an external power source (Vext control).

3- Monitoring cell State of Charge level to ensure proper power management.

Could anyone provide some guidance or examples on how to integrate the Li-ion charging circuit with the ESP32-C3 and manage the Vext control? Any help or references to similar designs would be much appreciated.

Answer 1

You implemented protection during Li-ion cell charging with the TP4056 Li-ion charger IC. But you didn't implement a Li-ion cell discharge protection. As you have it, the Li-ion cell will be over-discharged and permanently damaged.

The best solution is to add a Li-ion protector BMS circuit, which adds a second layer of protection during Li-ion cell charging, and protection from Li-ion cell over-discharge. However, you may be able to simply add an under-voltage cutout circuit, one that disconnects the Li-ion cell from every load if its voltage is too low, and that uses no more than a few microamps to operate. If it were me, I'd go for the protector BMS IC solution because it solves problems you haven't yet even considered.

Monitoring cell State of Charge level to ensure proper power management.

Buy or implement a ready-made solution: a BMS that includes a "fuel gauge" function. Look at "bq" chips from TI.