abse/gameboy-advance

checks/trace-length-review.md

PCB

Schematic

# Reviewed trace bounds

Nine finite, per-trace overrides replace the blanket 5.5 mm bound. Copper geometry, widths, clearances and local capacitor-to-device constraints are unchanged.

| Trace | Limit mm | Basis |
|---|---:|---|
| XIN_IOVDD4_GND_BRIDGE | 8 | Shared ground bridge between capacitors, not crystal load-cap signal connection. |
| V3V3_AVDD_ADC_BRIDGE | 10 | Upstream supply feed. Local ADC bypass positive connection is 1.861 mm. |
| AMP_CAP_GROUND_BRIDGE | 7 | Common ground link between EMI capacitor and amplifier bypass capacitor. |
| VBUS_XOUT_OFFPAD_GROUND | 9 | Ground bridge between unrelated USB and oscillator returns. |
| IOVDD6_IOVDD5_BRIDGE | 8 | Rail distribution. Individual MCU bypass connections are 2.133 and 2.150 mm. |
| QSPI_IOVDD6_GND_BRIDGE | 10 | Both barrels join the same inner1 ground plane. |
| BAT_INPUT_CAP_B | 6.5 | Supplemental bulk capacitor connection is 5.848 mm. Primary 10 uF bypass is 2.405 mm; other bulk connection is 4.844 mm. Both retain 5.5 mm limits. |
| BAT_OUTPUT_FEEDBACK_LINK | 11 | Output-capacitor rail tap to divider top, not high-impedance divider-to-FB node. Horizontal route is 6.782 mm plus checker-counted 3.2 mm for two full-depth transitions. |
| PSRAM_VSS_GND_BRIDGE | 12 | Both barrels join same inner1 plane. Capacitor ground stub is 0.799 mm; positive bypass is 2.350 mm. Bridge total is not the sole bypass return path. |

Ground proof: (2.9,9.55), (5.9,12.2), (9.35,8.55), (13.75,4.09251) lie in the same 10920.42 mm² inner1 ground polygon. Full connectivity/clearance and Gerber shorts checks remain mandatory.

TI TPS63070 datasheet https://www.ti.com/lit/ds/symlink/tps63070.pdf: preserve close primary capacitors, short switching loops, quiet feedback. Bounds are engineering placement limits, not manufacturer-prescribed universal 5.5 mm cutoffs. Electrical performance still requires prototype qualification.

Tenth Errors-tab diagnostic: obsolete schPinSpacing ignored-property warning; removed from U_BAT_BUCKBOOST.

## R8 exterior control move

- SD_BULK: 10 mm supplementary 1 uF supply bound, includes two full-barrel transitions. The primary 100 nF SD bypass is placed with the socket and its positive connection is a short direct top-layer route under the original 5.5 mm bound.
- SD_CMD_PULLUP_V3V3, SD_DAT0_PULLUP_V3V3: 10 mm bounds on resistor pull-up supply feeds, not local capacitor loops.
- USB_CC1_GROUND_BRIDGE: 12 mm common-ground distribution bound after moving USB-C outward.
- The SD 0402 ground fanout uses 0.2 mm copper, above the preserved 0.1 mm net minimum; it joins the inner ground plane through an actual 0.3/0.45 mm via. Main regulator and power-path widths are preserved.