ShiboSoftwareDev/linux-gameboy-advance
Restores PCB assembly metadata by assigning part numbers and 3D CAD models, removing test-point bodies, and validating top-side SMT solder-paste features without altering copper or pads.
- Version
- 1.0.17
- License
- unset
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- 0
POWER-REVISION.md
# Power corrections, revision 1.0.12
- U_2V5: Diodes AP2112K-2.5TRG1, SOT-25, JLCPCB C176945. Replaces U_1V8 without changing its pin mapping or placement. Input pin 1 and enable pin 3 receive 3.3 V, pin 2 is ground, pin 4 is unconnected, pin 5 supplies DDR1 at 2.5 V.
- U_2V8: Diodes AP2127K-2.8TRG1, SOT-23-5; same 1=IN, 2=GND, 3=EN, 4=NC, 5=OUT mapping. Supplies only codec AVCC and its decoupling/bulk capacitor. Input/output capacitors are 4.7 µF 0805 X7R, 16 V. JLCPCB C460327; exact manufacturer part verified in jlcsearch.
- 3.3 V I/O/USB/headphone/TV and 1.2 V core supplies retained. JP_BOOT recovery arrangement retained.
- The external battery range is now specified as 4.8–6.4 V. This keeps the AP63203 input above its 3.8 V minimum after the Schottky diode, resettable fuse, power switch, wiring, and load transients; the former 3.8 V board-level claim was not supportable.
- The AP63203 output-capacitor-to-inductor links are both physically routed at 0.50 mm instead of being narrowed to the 0.12 mm signal minimum.
- The former 4.7 Ω passive LCD backlight feed has been replaced by an AP3031 boost/current driver. Two series 1 Ω sense resistors set approximately 100 mA (`0.2 V / 2 Ω`), close to the panel rating while retaining margin below 110–120 mA.
- The reviewed V3V3 transition via was moved away from the inner-layer module trace. Its finished-hole-to-other-net-copper clearance is now 0.540 mm, above the 0.20 mm fabrication requirement.
Datasheet limits: DDR1 2.3–2.7 V (nominal 2.5); codec AVCC 2.5–3.1 V (nominal 2.8). AP2112 2.5 V ±2% gives 2.45–2.55 V; AP2127 2.8 V ±2% gives 2.744–2.856 V before load/transient effects.
Sources:
- Allwinner F1C100S datasheet, section 5.2: https://linux-sunxi.org/images/b/ba/F1C100s_Datasheet_V1.0.pdf
- AP2112: https://www.diodes.com/datasheet/download/AP2112.pdf
- AP2127, sections pin descriptions, electrical characteristics, package outline: https://www.diodes.com/datasheet/download/AP2127.pdf
- AP63200/AP63203: https://www.diodes.com/datasheet/download/AP63200-AP63201-AP63203-AP63205.pdf
- AP3031: https://datasheet.lcsc.com/lcsc/1811081712_Diodes-Incorporated-AP3031KTR-G1_C82636.pdf
- ER-TFT035IPS-6: https://www.buydisplay.com/download/manual/ER-TFT035IPS-6_Datasheet.pdf
- DRAM assembly part: https://jlcpcb.com/partdetail/DiodesIncorporated-AP2112K_25TRG1/C176945
The repaired prior board ran Linux using an external 2.5 V supply. That validates the diagnosis, not this unbuilt revision. Before production, prototype and measure startup order (Allwinner section 5.5), rail transients, core tolerance (nominal 1.2 V is the recommended upper bound), regulator temperatures, USB integrity and the fabricator's final stackup. Peripheral load budget and existing inventory shortages still apply.
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