A 4 layer board and measures 36mm in diameter. I will "hand solder" top side using a hot plate and the bottom probably with hot air, almost all components are on the top. Tjose are the layers:
- Signal
- GND
- Power 1V8 and 3V3 (except 3 traces I had to run on this layer as I forgot the buttons after routing everything...)
- Signal
Features and datasheets:
- nRF52833 (SIP module) microcontroller running on 1V8.
- Power management
- LiPo charger MAX1811ESA+ datasheet
- Battery supervisor (low voltage protection) TLV840MAPL3... datasheet
- 1V8 regulator XC9265C181MR-G datasheet
- Battery level reading circuit with moset DMC2400UV-7 datasheet
- Accelerometer and step counter LIS2DS12TR datasheet
- Vibration motor driver DRV2603RUNT datasheet
- External 8MB Flash MX25R6435FZNIL0 datasheet
- Biometric sensor (heart rate etc.)
- MAX30101EFD datasheet
- 5V boost regulator TPS61023DRLT datasheet and it's app note
- Round display
- 1.8V <=> logic shifter TXB0104QRUTRQ1 datasheet
- Display datasheet
- 3V3 voltage regulator (same as 1V8 one in Power Management)