跳转到内容
YBO 技术文档

20261024-2100-air-hub-mini-part-reduction Air Hub Mini revision D: part reduction (85 to 52 placed parts)

  • status: completed
  • priority: P2
  • owner: worker/session-ybo-46
  • createdAt: 2026-10-24 21:00

Description

章节标题：“Description”

On 2026-10-24 the owner approved a part-reduction pass on the Air Hub Mini (items A–E of the review, "a 可以 b 可以 c 可以 d 可以 e 可以"). The Air Hub and Air Hub Pro are not affected.

  • A, one supply rail: the LMR36520 makes 3.3 V straight from VIN. The 5 V rail and the TPS62A02 are removed. The TJA1463 (5 V VCC/VBAT) becomes a TI TCAN3413: 3.3 V only, ±58 V bus standoff, SOIC-8, STB tied to GND.
  • B, 5 V-only USB-C: 5.1 kΩ Rd on CC1/CC2 replace the HUSB238 PD sink. A 60 V Schottky (B360A) replaces the LM74800 ideal diode and its FET pair. The VBUS-sense divider that only reached a test point is removed. USB priority stays: the LM74502 OV pin still cuts the M8 path above 4.4 V VBUS.
  • C, straps and LEDs:
    • The LEDs move from the boot straps IO8/IO9 to IO6/IO7, so the strap pull-ups and the IO15 pull-down are not needed.
    • The PWR LED is dropped.
    • The two remaining LEDs differ in colour: SYS green, RADIO blue.
  • D, no long-press reset: the 1 MΩ / 4.7 µF RC, the 74LVC1G14 and the 2N7002 go. Hangs are covered by the C6 watchdogs. A PAIR key held at boot still triggers the factory reset. PAIR uses the internal pull-up, so its external pull-up and 100 nF are removed too.
  • E, MG24 SWD: the 5-pin header becomes pogo pads (SWCLK, SWDIO, RESET, GND).

Acceptance criteria:

  1. Schematic: ERC 0 and net verification 0 mismatches. The Pro / Air Hub generators keep their output, because the shared builders change only through optional parameters.
  2. PCB: DRC 0 unconnected, 0 clearance errors, 0 parity. The EMC rerun has no errors.
  3. Cost: the cost sheet is updated.
  4. Docs: the spec (Mini USB input), the design appendix and the reference-board page describe revision D; the workspace README and pinmap follow.
  5. Quality gate: bun run docs:lint && bun run docs:build && git diff --check passes.

ActiveForm

章节标题：“ActiveForm”

Reducing the Air Hub Mini part count

Dependencies

章节标题：“Dependencies”
  • blocked by: (none)
  • blocks: (none)

Notes

章节标题：“Notes”

Results (2026-10-24):

  • Schematic (revision D): 52 placed parts in 41 BOM lines, down from 85 parts in 53 lines. ERC 0; net check 0 mismatches on 84 nets.
  • Datasheet values:
    • LMR36520 table 8-1 at 3.3 V / 400 kHz: 6.8 µH, 100 kΩ / 43.2 kΩ, 3 × 22 µF.
    • LMR36520 minimum on-time is 92 ns; the on-time at 36 V input is 230 ns.
    • LMR36520 VCC UVLO is 4.0 V rising (max) and 3.5 V falling (max).
    • TCAN3413 SLLSFS8A: VOD(DOM) 1.4–3 V into 45–70 Ω; ±58 V bus fault protection.
  • PCB: DRC 0 unconnected, 0 errors, 0 parity. Three lib_footprint_mismatch warnings remain (fiducials, board properties).
    • EMC: 13 findings, 0 errors (7 warnings: the USB pair and MG24_SWCLK on the outer layer, two ground domains by design, buck harmonics). Revision C had 30 findings with 5 errors.
    • A locked via at the NUP3105L ground pad fixes ES-002.
  • Cost: 22.06 → 18.87 USD per board at 100 boards. TCAN3413DR and B360A-13-F are estimates; their LCSC codes are still to be checked.
  • Open:
    • LMR36520 dropout from 5 V USB through the Schottky (VIN about 4.3–4.6 V) needs a bench check.
    • TCAN3413 levels on the X01 harness and its NMEA 2000 acceptance need checking.
    • The block and power-tree diagrams in air-hub-mini/diagrams/ still show revision C.