Design Log DEC 063 ctl poe l1 selection yageo pa4343333nlt acf forward output inductor - thepinkmile/Enigma-NG GitHub Wiki
DEC-063 - CTL PoE L1 Selection: Yageo PA4343.333NLT (ACF Forward Output Inductor)
| Field | Value |
|---|---|
| Decision ID | DEC-063 |
| Status | Confirmed |
| Date | 2026-05-09 |
| Author | Izzyonstage & Copilot (session e39f3cc4) |
| Amends | DEC-062 (L1 "part selection pending" resolved) |
Context
The ACF Forward topology change (DEC-062) introduced L1 as a new output inductor requirement (DR-CTL-25). Three candidates were evaluated:
- Würth 74436413300: Eliminated - oversized body, non-standard 3-pin configuration, and marginal saturation current.
- Bourns SRP1265A-330M: Eliminated - carbonyl powder (iron) core. At 200kHz switching frequency, iron-powder cores exhibit unacceptable core loss. Hard disqualified by DR-CTL-25 (ferrite only, no iron-powder cores).
- Yageo PA4343.333NLT: Only viable option. 33µH ±20%, Isat=11A @30% inductance drop, DCR typ 48mΩ / max 58mΩ, Irms 8A, 13.5×12.5×6.2mm, shielded ferrite SMT, AEC-Q200.
Decision
L1 selected: Yageo PA4343.333NLT. DigiKey: 553-3457-1-ND; Mouser: 673-PA4343.333NLT; JLCPCB: C2453886. KiCAD footprint downloaded (zip in temp folder, pending library addition at schematic capture stage).
Rationale
- All three candidates share the same inductance value and nominal Isat figure, but the Würth part has procurement and pin-count drawbacks, and the Bourns part is disqualified on core material grounds.
- Yageo PA4343.333NLT is the only candidate meeting the ferrite core, Isat (≥6A), and form-factor requirements of DR-CTL-25.
DCR Compliance Note
DR-CTL-25 specifies DCR ≤50mΩ. The Yageo PA4343.333NLT has a typical DCR of 48mΩ (compliant) but a manufacturer maximum of 58mΩ (non-compliant). This is the best available option at current procurement time; accepted as a qualified exception. The DR limit is retained at ≤50mΩ and this entry documents the exception.
Files Changed
design/Electronics/Controller/Design_Spec.md: DR-CTL-25 updated (part selected, DCR exception noted). BOM L1 row updated with MPN and supplier PNs.design/Electronics/Consolidated_BOM.md: CTL L1 row updated (TBD → PA4343.333NLT with supplier PNs).