I have a 3Cell LiPo battery which I am going to use with an RC Car, and I want to design a circuit to protect the battery cells from going under ~3.3v each. So what do you think of this design?
As you can see in the schematic, I am using the MCP111-315 which detects voltage drop below 3.08V (active-low, open-drain).
Diodes are used to increase the detected voltage level, so it will detect the power at 3.08 + Vf (3.3 is my preferred value). However, the MCP111 only draws 1.75uA (max) and most datasheets only provides Vf for as low as 1mA. Is there a more reliable way to get this ~0.2 voltage drop at such low current? maybe a voltage divider?
I am using optocouplers since I don't have a common ground between Cell 1 & 2 and the MCU
Any cell that falls below 3.3V should pull the MCU pin down (MCU Internal pull-up resistor is turned on on that pin)
C1, C2 and C3 are bypass capacitors for the MCP111, whereas R1 & R2 are series resistors for the optocouplers LED.
Any suggestions on this design or do you have a simpler idea?