Duplicate GND nets found (two separate nets named "GND") — merge into a single ground net to avoid split returns; ensure all shields and GND pins join the same GND net. Place VBUS protection and fuse: locate F1 and required TVS as close as possible to J1 VBUS pads; keep VIN trace from J1 to U2 <5 mm and as wide/short as feasible. USB data routing: route D+ and D- as a controlled-impedance differential pair with matched lengths and consistent spacing; minimize stubs to TVS/CM choke and place TVS with minimal stub. Verify TVS capacitance <1 pF per data line. Common-mode choke and TVS placement: place L1 and D1 immediately after connector on the data lines; keep differential pair routing continuous through L1. Power decoupling and LDO: place C1 (VIN decoupling) and C2 (VOUT decoupling) as close as possible to U2 pins with short traces and ground vias; verify capacitor types/values meet XC6220B331MR datasheet stability requirements. U1 ground/EP: connect the nRF52840 EP (exposed pad) to the GND plane with multiple thermal/ground vias; ensure a continuous ground plane and stitching vias around RF section. Antenna and RF routing: provide antenna keepout, route RF feed from ANT/U.FL as 50 Ω transmission line, avoid ground pours under the antenna, and maintain required clearance from metal and mounting holes. SWD header and programming accessibility: ensure J2 is accessible and SWD traces (SWDIO, SWDCLK, nRESET) are short and free of vias where possible. General layout checks: run ERC/DRC for missing footprints, airwires, overlapping copper, trace-to-pad clearances, minimum trace widths, and verify no copper under antenna keepout. Priority actions: 1) Fix duplicate GND nets (critical). 2) Re-locate/confirm placement of F1, TVS, and L1 at J1 (high). 3) Check LDO decoupling placement and EP stitching (high). 4) Review USB differential pair routing and antenna keepout (high).

USB

USB

Consumer Electronics

Bluetooth

3.3 V

Consolidated manufacturability analysis and prioritized recommendations: 1) Duplicate GND nets: Multiple nets named "GND" exist — merge into a single GND net so all shield and GND pins share the same return. This is critical to avoid split returns and EMI issues. 2) VBUS protection & placement: Place F1 (PTC/fuse) and the dedicated VBUS TVS as close as possible to J1 VBUS pads. Keep the VIN trace from J1 to U2 <5 mm and as short/wide as practical. 3) USB data protection & routing: Ensure bidirectional TVS on D+ and D- has ≤1 pF capacitance per line. Place the common‑mode choke (L1) immediately after J1, with the differential pair routed continuously through it. Minimize stubs to TVS/CM choke. 4) Differential pair integrity: Route D+ / D- as a matched-length controlled-impedance differential pair (target ~90 Ω diff), consistent spacing, length-matched, with no unnecessary vias; verify settled lengths for USB2.0 timing. 5) LDO decoupling & EP stitching: Place VIN decoupling (C1) and VOUT decoupling (C2/C3) immediately adjacent to U2 VIN/VOUT pins with short traces and ground vias. Verify C type/values meet XC6220B331MR stability and transient requirements. Connect U2 exposed pad to ground plane with multiple thermal/ground vias and stitching around RF area. 6) Antenna & RF keepout: Enforce antenna keepout region, route RF feed as a 50 Ω transmission line (microstrip/stripline per stackup), avoid copper pours under antenna, and maintain required clearances from mounting holes and metal. Add stitching vias at ground plane edges near RF as needed. 7) SWD/programming accessibility: Ensure J2 is physically accessible; keep SWDIO, SWDCLK, and nRESET traces short and avoid vias where possible for reliability during programming. 8) Footprints & assembly: Verify all footprints, pad sizes, solder mask, and courtyard clearances for manufacturability; ensure board-edge USB-C mechanical clearance and pick-and-place access; include fiducials. 9) ERC/DRC checks: Run full ERC/DRC for missing footprints, airwires, overlapping copper, trace-to-pad clearances, minimum trace widths, and copper in antenna keepout. Fix high-priority items before fabrication. Prioritized next actions: 1) Merge duplicate GND nets (critical). 2) Re-locate/confirm placement of F1, TVS (VBUS), and L1 at J1 (high). 3) Verify LDO decoupling placement, component values, and EP stitching for U2 (high). 4) Review USB D+/D- differential routing and verify TVS capacitance <1 pF (high). 5) Validate antenna keepout and 50 Ω feed geometry (medium). 6) Run ERC/DRC and iterate on layout to resolve any remaining DRC/assembly issues (medium). End of manufacturability_review.

5 V