What's inside WeDo 2.0 controller brick 

Detailed description of WeDo 2.0 controller brick PCB

Warning: this information was gathered by close looking at PCB and making some voltages and continuity measurement. I may be wrong sometimes!

PCB top

 

1, 2	I/O connectors, dubbed "Power Functions 2.0". LEGO proprietary design, 1.27mm pitch. Square pad denotes pin 1.
3	Dual motor driver, On Semiconductor LB1836. Same chip used in NXT, EV3, Power Functions receiver.
4	CPU / Bluetooth radio, Texas Instruments CC2640.
5	+5V filtering capacitor.
6	Boost switcher converter, Texas Instruments TPS61032. Generates +5V supply from battery. Chip is 1A rated.
7	+Vbattery filtering capacitor.
8, 9	Conditionning chip for IO connectors pin 5/6. Exact function yet to be determined. Powered from +3.3V_CPU
10	+3.3V linear regulator (LDO). Exact type unknown. Converts +5V to +3.3V_CPU for CC2640 and (8)(9) conditionning chips.
11	+3.3V linear regulator (LDO). Exact type unknown. Converts +5V to +3.3V_IO for I/O connectors.
12	Battery connector. Middle pin function unknown, might allow to distinguish between alkaline cells and rechargeable battery.

PCB bottom

 

1, 2	I/O connectors, dubbed "Power Functions 2.0". LEGO proprietary design, 1.27mm pitch.
3	Piezzoelectric buzzer
4	Ceramic Bluetooth antenna
5	+5V filtering capacitor.
6	Boost switcher converter inductor.
7	+Vbattery filtering capacitor.
8	Hex Schmidt trigger (74HCT14), +5V powered. Function unknown. Lower threshold of HCT compared to HC could mean it's used as level translator for 3.3V signals to 5V domain.
9	Power on push button.
10	RGB LED.
11	Input fuse on +Vbattery. Seems to be a Bourns MF-NSML150 resettable fuse, 1.5A rated.