Project Status and Action Items
Worked for 1 min 27 sec
Done. I deleted
CN1 and moved U_MCU/Pico to the top of the board; it is now centered at about (10 mm, 88 mm) with its top edge just inside the board outline.Open item: the Pico was clamped at the board edge, so if you want more clearance from the top edge I can drop it slightly lower.
I need a power switch and some output LEDs
Thought for 5 sec
I’ll add a low-current front-panel power/enable switch rather than a high-current 12 V path switch, plus output/status LEDs with current-limiting resistors, then verify the schematic changes.
Worked for 1 min 54 sec
Added the power switch and output LEDs.
SW_PWR is a low-current front-panel switch that pulls Pico 3V3_EN to GND to turn logic off, and I added green indicators for BUS_12V and VOUT_19V5 with 4.7kΩ and 8.2kΩ series resistors.Open items:
- These are placed near the top/front-panel area but not routed yet.
- If you intended a true high-current input disconnect instead of a Pico enable switch, that needs a different switch/contactor architecture.
Route controls and verify
Use high-current switch
Route switch and LEDs
Add LED labels
Run design review
Refine this doc
Ask about this doc
JLCPCB BoM Review — Rackmount 12V Distribution PSU
Status
Draft review based on the user-supplied BoM. Treat this as a starting point; several items likely need to change before schematic capture and layout.
Manufacturing Constraint
- Preferred manufacturer/assembler: JLCPCB.
- Prefer components with JLCPCB/LCSC order codes where practical.
- Footprints must match JLCPCB assembly capabilities and the actual selected package variants.
Supplied BoM Summary
Input Filtering
- C1: Samsung CL10B224KA8NNNC, C21120, 0603, 220nF class input HF capacitor.
- C2: Samsung CL32B226KAJNNNE, C309062, 1210, 22uF class MLCC, quantity 3.
- C3: jieerrui MA25V220M6X8, C46550464, 25V 220uF electrolytic, quantity 2.
Controller & Power Stage
- U1: TI LM5122ZPWPR, C2658810.
- MOSFETs: Infineon BSC010NE2LS, C152368, quantity 2.
- L1: TAI-TECH TMPC1707HP-4R7MG-D, C357285, 4.7uH.
- C_BOOT: Samsung CL05B104KO5NNN, C1525, 0402, 100nF.
- R_EN: UNI-ROYAL 0805W8J0104T5E, C25611, 100kΩ.
Feedback & Compensation
- R_FB_UPPER: UNI-ROYAL 0805W8F2373T5E, C17568, 237kΩ.
- R_FB_LOWER: UNI-ROYAL 0805W8F1002T5E, C17414, 10kΩ.
- R_COMP: UNI-ROYAL 0805W8F1002T5E, C17414, 10kΩ.
- C_COMP1: Samsung CL10B472KB8NNNC, C1621, 4.7nF.
- C_COMP2: YAGEO CC0603JRNPO9BN101, C14665, 100pF C0G/NP0.
Output Filtering / Protection / Connector
- Output bulk capacitors: MA25V220M6X8, C46550464, quantity 2.
- Output bulk capacitors: ROQANG RVT1E221M0607, C2918361, quantity 4.
- HF output MLCC: Samsung CL32B226KAJNNNE, C309062, quantity 3.
- Additional 50V ceramics: 1uF C141772 and 0.1uF C125205.
- TV1: Brightking SMBJ24A, C87268.
- R_BLD: FOJAN FRC0603F4702TS, C2907042, 47kΩ.
- DC1: G-Switch DC-S007B-D025-15A, C7464909, 5.5mm barrel jack, 15A rating.
Telemetry
- INA181A2IDBVR current sense amplifiers, C2058784, quantity 2.
- Murata NCP18XH103F03RB thermistors, C13564, quantity 2.
- YAGEO RT0603BRD07110KL / RT0603BRD0710KL class 10kΩ precision resistors, C95204, quantity 2.
Immediate Engineering Review
1. LM5122 Boost Stage Scope
The supplied BoM looks like one 12V-to-19.5V boost daughterboard channel, not the full rack distribution board. That is acceptable if the main board provides 12V slots and this stage is replicated on daughterboards.
2. Power Budget Conflict
One 180W output requires roughly 16.7A from 12V at 90% efficiency. A 750W Dell D750E-S1 supports about four 180W outputs at full load before margin. 8–12 outputs require oversubscription, multiple PSUs, or lower per-slot configured limits.
3. Barrel Jack Current Rating
The selected 15A DC barrel jack is above the stated 10A output current target, but 10A through 5.5mm barrel connectors is mechanically and thermally aggressive. Validate connector temperature rise, mating plug rating, cable gauge, and user safety margins.
4. MOSFET Quantity / Ratings
A synchronous LM5122 boost converter normally requires two MOSFETs. BSC010NE2LS has very low RDS(on), but the package thermal path, gate charge, switching losses, and layout must be checked for 180W continuous output.
5. Inductor Check Required
The 4.7uH inductor must be checked for saturation current, RMS current, DCR loss, thermal rise, and ripple current at the selected switching frequency. This is a critical validation item before locking the BoM.
6. Capacitor Voltage / Ripple / DC Bias
25V electrolytics on a 19.5V output have limited voltage margin. This may be acceptable for regulated output but is tight under transients; 35V parts may be safer if size/cost allow. 1210 22uF MLCC effective capacitance under DC bias must be derated.
7. TVS Selection
SMBJ24A on a 19.5V output is plausible but must be verified against the boost converter regulation tolerance and load transient behavior. Make sure the standoff, breakdown, and clamp levels do not cause nuisance conduction or fail to protect downstream mini PCs.
8. Current Sense Architecture
Two INA181 devices could support input and output current sensing for a boost module. For a 12-slot rack controller, expect either 12 per-slot sensors plus one total input sensor, or a multiplexed / digital current monitor architecture.
9. Missing Items for Full System
The current BoM does not yet include:
- Bellwether 70012-1111 HPSU input connector.
- Per-slot eFuse/hot-swap/high-side switch devices.
- MCU and Ethernet hardware.
- 3.3V regulator for logic.
- PSU present/enable/fault interface circuitry.
- Slot connectors between main board and boost daughterboards.
- Debug/programming connector.
- Fans / fan control, if needed.
- Fuses or hardware short-circuit protection.
- Test points.
Recommended Direction
- Keep this BoM as the boost daughterboard candidate.
- Design the rack distribution board separately around 12V input, slot protection, telemetry, MCU, and Ethernet.
- Create one validated boost-module schematic first if the daughterboard is also in scope, then replicate only after efficiency/thermal checks.
- For the main distribution board, use hardware eFuse/current-limit devices per slot rather than relying on firmware and a bare MOSFET for fault protection.
Open Validation Items
- Confirm whether the LM5122 boost module is part of this project or a separate daughterboard project.
- Obtain and verify Bellwether 70012-1111 footprint/mechanical data.
- Confirm target slot count for Rev A: 8, 10, or 12.
- Confirm whether Rev A needs dual PSU support or only mechanical/electrical allowance for future dual PSU.
- Calculate LM5122 power-stage component values from datasheet / WEBENCH / TI calculator before finalizing compensation and inductor choice.
- Confirm mini-PC cable and barrel plug current rating at 19.5V / 10A.
Status
Manufacturing Constraint
Supplied BoM Summary
Input Filtering
Controller & Power Stage
Feedback & Compensation
Output Filtering / Protection / Connector
Telemetry
Immediate Engineering Review
1. LM5122 Boost Stage Scope
2. Power Budget Conflict
3. Barrel Jack Current Rating
4. MOSFET Quantity / Ratings
5. Inductor Check Required
6. Capacitor Voltage / Ripple / DC Bias
7. TVS Selection
8. Current Sense Architecture
9. Missing Items for Full System
Recommended Direction
Open Validation Items
