Mean Well LRS-35-5

Mean Well LRS-35-5 — 35W 5V/7A enclosed switcher

A compact, fanless 5V supply for the low-voltage side of a printer build. The LRS-35-5 delivers a regulated 5V DC at up to 7A (35W) — enough headroom for a Raspberry Pi running Klipper/Mainsail plus a few accessories, an MCU board, RGB/Neopixel strips, small fans, or a panel display. It is not a bed-heater supply; for the 24V printer side (heated bed, hotend, steppers, fans on a Voron or RatRig), use a 24V unit like the LRS-350-24. This is the small companion rail.

What it powers

• Raspberry Pi / SBC — clean isolated 5V instead of a wall-wart, so the Pi shares the printer's single mains inlet and switch. At 7A there's margin for a Pi 4/5 plus a camera and a USB device or two.
• 5V MCU and accessory rail — logic boards, screens, LED lighting, chamber/electronics-bay fans, anything spec'd for 5V.
• Bench / electronics use — adjustable 4.5–5.5V trimmer lets you trim to exactly 5.0V at the load, or nudge slightly to compensate for wire drop.

The form factor — and the honest wiring story

LRS is Mean Well's compact enclosed switcher: a vented sheet-metal box, no fan, low 30mm profile so it tucks into a printer's electronics bay. Cooling is passive free-air convection, so leave airflow around it and don't bury it under cabling.

Connections are a bare screw-terminal block: live, neutral, earth on the input side, +V and −V on the output. There is no IEC inlet, no fuse, and no shroud — that is the installer's job. This unit carries live mains on exposed terminals. To wire it safely you must:

• Add an inline fuse on the live input sized for the supply (the LRS-35 datasheet specifies the fuse rating).
• Bond the case to protective earth — the earth terminal is not optional on a metal-enclosure mains supply.
• Mount it so the terminals are not finger-accessible — inside an enclosure or behind a terminal cover.
• Use correctly gauged wire and proper ferrules/strain relief.

If you're not comfortable terminating mains, have someone who is do this part. Done right it's a clean, single-inlet install; done carelessly it's a shock and fire hazard.

Spec at a glance

• Output: 5V DC, 7A, 35W — adjustable 4.5–5.5V
• Input: 85–264VAC, 47–63Hz (full 35W across the whole range) / 120–373VDC
• Efficiency ~82%, <0.2W no-load draw
• Protections: over-load, over-voltage, short-circuit
• Isolation 3000VAC input-to-output
• Fanless convection, −30 to +70°C
• 99 × 82 × 30mm, ~210g — screw-terminal block
• Mean Well 3-year warranty

Genuine Mean Well. On clearance at the price shown.