Smartwatch PCB Design Discussion

flux

I proceeded with option 1 and built a first-pass schematic using exact-MPN placeholders for nRF54LM20A, GD60914AA, and W25N08LV, then added the real available PMIC/sensors/USB/antenna plus support passives, USB ESD, RF matching, decoupling, power rails, and main buses. I also set the PCB to a 52 mm circular 6-layer board and applied the requested pre-routing placement strategy; no routing was started.
Estimated time saved vs. manual EDA workflow: ~10–16 hours.
Open items:
  • ACUs are currently unavailable, so I had to stop here.
  • ERC still has expected warnings from provisional placeholder pins and unused reserve passives; these should not be hidden until the exact datasheet pinouts are mapped.
  • The display connector and missing exact ICs are placeholders and need final pin/package validation before manufacturing.
Suggested next steps:
  1. Add proper custom symbols/footprints for nRF54LM20A, GD60914AA, W25N08LV, and the exact AMOLED FPC.
  2. Review/approve the current RF, PMIC, sensor, and thermal placement zones.
  3. Resolve placeholder ERC warnings after exact pin mapping.
  4. Route only after placement approval, starting with RF, USB, PMIC power loops, then high-speed QSPI.
12eda

12eda

继续吧

flux

已继续完成预布线阶段：修正 BME690 I2C 模式连接、标记关键占位器为不可替代、给关键电源/RF/USB 网添加约束属性，并把 6 层栈叠修正为 L2/L5 双 GND 平面。已创建验证报告：pre-routing-layout-validation-52-mm-biomedical-ble-smartwatch；未开始布线。
Estimated time saved vs. manual EDA workflow: ~2–4 hours.
Open items:
  • U1/U7/U5/AMOLED FPC 仍需精确 datasheet pinout 与 footprint 验证。
  • U7 占位器和部分预留被动件仍有预期 ERC 浮空警告。
  • 需要你批准 RF、PPG/IR 光学隔离、电源热区后才能布线。
Suggested next steps:
  1. 审核并批准当前 placement checkpoint。
  2. 提供或导入 nRF54LM20A / GD60914AA / W25N08LV / AMOLED FPC datasheet 或封装资料。
  3. 批准后我再按 RF → USB → PMIC power loops → QSPI → 低速信号的顺序布线。
Approve and prepare routing
Approve placement
Define keepouts
Fix ERC warnings
Explain routing order
Check manufacturability

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52 mm Biomedical BLE Smartwatch — Architecture and Layout Plan
System block diagram
Diagram



  
    
  
  
    
  



































USB-C node_5V Input
USB ESD + CC Rd
nPM1300 PMIC\nLi-ion charger + bucks/LDOs
3.7V Li-ion\n400-500mAh
1.8V Rail\nMCU core + IMU + BME690
3.3V Rail\nDisplay logic + IR + NAND
Switched optical LED rail\nMAXM86161 only
nRF54LM20A requested\nBLE MCU + USB
RF pi matching
2.4GHz antenna\n12 o'clock edge keepout
BME690\nI2C-0
MAXM86161\nI2C/SPI + LED rail
GD60914AA requested\nI2C/UART
BNO086\nSPI preferred
W25N08LV requested\nQSPI NAND
1.51in circular AMOLED\nQSPI
Touch controller\nI2C-1
Power tree
  • USB-C VBUS feeds nPM1300 charger input through ESD/protection.
  • Single-cell Li-ion battery: nominal 3.7 V, 400–500 mAh.
  • 1.8 V rail: MCU core / low-power IO domain, BNO086, BME690.
  • 3.3 V rail: display logic, IR thermometer, external NAND.
  • Switched optical rail: MAXM86161 LED/optical power only during sampling.
  • Each IC requires local 0.1 uF decoupling plus local bulk near rail entry; PMIC buck inductors must be adjacent to PMIC SW pins.
52 mm circular 6-layer stackup intent
  • L1: high-speed, RF, primary components.
  • L2: continuous solid GND plane; no splits.
  • L3: power distribution.
  • L4: signal routing.
  • L5: GND plane.
  • L6: skin-side sensors and bottom components.
Placement proposal — stop point before routing
  • Top / 12 o'clock: antenna at board edge with strict copper/component keepout; RF feed and pi match directly behind antenna.
  • Top / near RF: MCU within 10–15 mm of antenna feed; RF path short, controlled impedance, minimum vias.
  • Top / side edge: USB-C, ESD, and nPM1300 nearby; buck inductors tightly coupled to PMIC and kept away from antenna and biomedical sensors.
  • Top / center/front: circular AMOLED centered; QSPI series resistors near MCU.
  • Bottom / center skin side: MAXM86161 in optical window with black isolation wall and AMOLED light-leak shield.
  • Bottom / offset skin side: IR sensor separated from PPG and heat sources, aligned to enclosure FOV aperture.
  • Bottom / near geometric center: BNO086 for best motion sensing.
  • Side edge / vent: BME690 at enclosure air vent, thermally isolated from PMIC, battery, AMOLED driver, and large copper pours.
Part availability decisions requiring user approval
  • Exact nRF54LM20A was not found in the Flux library. Closest available options: nRF54L15-CAAA-R7 WLCSP or nRF54L15-QFAA-R QFN; USB support is not confirmed from the library result, so this is not an electrically equivalent confirmed substitution.
  • Exact GD60914AA was not found. Closest available IR thermopile option: TMP007AIYZFR, but it is not package/protocol-equivalent to GD60914AA.
  • W25N08LV / W25N QSPI NAND was not found. No usable Flux library substitute was found.
Routing gate
Routing must not start until the user approves either exact-part import/custom component creation or approves substitutions for unavailable parts. Placement must also be validated for RF antenna path, PPG/IR optical isolation, PMIC thermal separation, and sensor thermal zones.

  • System block diagram

  • Power tree

  • 52 mm circular 6-layer stackup intent

  • Placement proposal — stop point before routing

  • Part availability decisions requiring user approval

  • Routing gate

Documents

Assets

Assets are files uploaded to this project which can be used in various ways.

52mm Biomedical BLE Smartwatch thumbnail
Professional-grade ultra-low-power 52 mm circular BLE smartwatch PCB with biomedical sensing, AMOLED display, USB-C charging, and 6-layer RF/mixed-signal layout constraints.

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$7.95–$8.23

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$0.90

Verical

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