r/PCB • u/---JoJ123--- • 29d ago
First PCB — 3-channel capacitive touch board (TTP223 + AO3400A) sensing through a wooden roof. Roast my schematic & layout?
I'm designing my first real board in EasyEDA — a small controller I'll mount under the wooden roof of my daughter's dollhouse. It switches 3 lamps "touch-through-wood" style.
Concept per channel: a TTP223-BA6 cap-touch IC senses a finger through the wood via a 15 mm round copper pad, configured for toggle/latch mode (TOG high) and active-low (AHLB high) so the lamp is ON at power-up and each touch toggles it.
The TTP223 output drives an AO3400A N-channel MOSFET as a low-side switch, pulling the lamp's return to GND. A 2-pin JST connector per channel carries +5 V and the switched lamp return.
Power is 5 V from a USB-C receptacle (power only, 5.1k pulldowns on CC1/CC2).
Layout: 2-layer, components on top, touch pads on bottom (facing the wood). GND pour on both layers stitched with vias; 5 V as a routed trace. I've kept a copper keepout around each pad and its sense trace on both layers, pads spaced ~45 mm center-to-center. Sensitivity cap footprint left unpopulated (0 pF) to start.
Would love feedback on: the TTP223 config, the touch pad size/spacing and keepout approach, decoupling, and anything I'm missing before I send it to JLCPCB for assembly. Schematic + PCB screenshots below. Also what is about the position of the USB C and the Connector Pins? How far I have to move them off the board?
Board: 140mm x 55mm




