Hello.
Back several months ago @Thea shared the list of capacitive touch controller ICs they found available on LCSC, and I think these are quite interesting, so I decided to pick one and make a devboard out of it.
The part I picked is AI08 from Xiamen Xinwang Electronic Technology (or they called themselves Sam&Wing on LCSC). This chip’s advantage is that:
- Has 8 input channels. Plenty for most projects.
- Easy to use. Could work with just some R and C components.
- Comes with auto-calibration when surrounding environment changes.
- BCD output. Straightforward to interface with MCU (or even without MCU).
- Easy to solder in an SOP-16 package.
- Cheap (around 50 cents @ 1 pieces.)
Note: This manufacturer (and others, such as AD Semicon) have many, many more similar chips available with various channel count (1-12) and output type (Parallel, BCD, I2C, etc.) be sure to look around if you want something else.
The board’s capacitive touch interfaces are designed using Microchip’s great appnote AN2934.
(Please google that as I can only put 2 links in.)
For the output side, apart from the BCD output provided, I added an 74HC138 IC to decode the BCD output to 8 parallel outputs. You could also use an 74HC238 for active-high output too. The flags output by the chip (no detection and calibration in-progress) are also decoded with some logic gates. LED indicators are provided on every signals.
The AI08 (and the logic chips) supports voltages between 2.5-5.5V. I included footprints for both TO-92 and SOT-89 versions of the 78Lxx voltage regulators so you can choose which voltage you want.
The PCB was manufactured with high quality as expected and the result turns out great! The touch and no-touch events are recognized accurately (but very sensitive). I really like it and will be sure to use such touch IC in my projects in the future.
Thanks for reading! 
