Document for understanding the circuit diagram

Charge Controllers
1

Hi If possible share any documents that help o understand the circuit connections in my doughts areas
Why AOT266L is connected Parallel across Q3 , Q1, Q2

2

Which charge controller?

3

PWM 2420 LUS, Also have some dought why Q3 connected on Low side control

4

As mentioned in the schematic, the AOT266L is a THT alternative to the SMT MOSFETs, which can be attached to a heat sink at the back of the PCB. The PCB allows both options and provides both footprints.

The switches are at the low side because it’s cheaper (you don’t need a high-side MOSFET driver or a PMOS).