LLT ENGINEERING · Application analysis
Published · Updated
M25 Power and Signal Connector: Hybrid Layouts and Ratings
Choosing an M25 for mixed power and signal starts with your circuit list, not the shell. This guide walks through per-configuration ratings, the 2+6 and 3+8 hybrid groups, cable and sealing gates, and the conditions the public data does not yet prove for your exact part number.
Scope and boundaries
Applies to LLT M25 configurations: 2–8 pin power versions, 20/24-pin signal versions, and 2+6 / 3+8 hybrid layouts, in threaded or self-lock coupling with front-panel, rear-panel, flange, or in-line mounting. Ratings quoted are per configuration from the public catalog summary. Mating compatibility, panel cutouts, temperature rise, long-term immersion, washdown, and certification coverage must be verified per part number against formal drawings and documents.
Start with the circuit list, not the interface
The first constraint on an M25 selection is the load list, not the connector diameter. The series targets motors, inverters, and intelligent equipment that combine higher current with multiple signal lines on one interface. Write down every loop with its real voltage, continuous and peak current, then map each loop to a contact group.
An M25 hybrid layout only fits your machine when the power group, the signal group, the cable, and the mounting each pass their own check; the series maximum never covers a specific configuration. A shell that fits the panel says nothing about whether its contacts, wire range, and sealing match your duty.
Sources: LLT public connector catalog · LLT selection guide
Read the ratings per configuration
The public summary rates each pin count separately. The 2-, 3-, and 4-pin configurations carry a 250 V, 35 A rating, while the 20- and 24-pin versions are rated 100 V, 5 A with a maximum conductor of 0.3 mm². Between them, 5- and 6-pin versions sit at 250 V, 20 A up to 1.5 mm², and the 8-pin drops the conductor limit to 1 mm². Even within the 35 A group the conductor ceiling changes: up to 4 mm² for 2- and 3-pin, 2.5 mm² for 4-pin.
Each row applies only to its own configuration, and rated current is marked per contact or contact group. When several cores carry current together, conductor size, ambient temperature, and heat dissipation all shift the temperature rise — treat the table as screening, then confirm against the specification under your actual duty.
Sources: LLT public connector catalog · Technical applicability
Hybrid layouts are two circuits sharing one shell
The 2+6 and 3+8 arrangements put a power group and a signal group in one housing. On the attached 90° catalog page, the 2+6 and 3+8 configurations list a power group of 20 A at 250 V and a signal group of 5 A at 100 V. Straight and flange versions are rated on their own catalog pages, so match the page to your mounting form before quoting numbers.
Two rules follow. Never add the two group currents into a machine-level rating; each group is checked against its own current, voltage, and wiring. And a shared shell does not create mateability — contact count, face layout, viewing direction, keying, and pin-versus-socket gender must all line up with the mating part.
Sources: LLT public connector catalog · Technical applicability
Run this branch before you shortlist
If any circuit exceeds the current or conductor limit of its contact group, move that circuit to a second interface or a higher-current series such as M29; until the full part number and the formal drawing are confirmed, the configuration cannot be judged suitable. The same holds for signal loops that need shielding or a fixed pin assignment — check them against the face drawing of the exact SKU.
Stop the selection if you catch yourself assuming that a different seal can be swapped in for an out-of-range cable, that equal pin counts guarantee a mate, or that the 35 A figure transfers to a hybrid group. Each assumption needs a document; without one, the answer is 'not yet confirmed.'
Sources: LLT public connector catalog · Technical applicability
Treat conductor size and cable OD as two gates
The maximum conductor column is per core, in mm², and screens whether your wire can be terminated; it does not set the cable's current capacity alone. The jacket OD, in mm, is a separate gate that must fall inside the sealing and clamping range of the exact configuration. Two cables with equal cross-section can differ in OD through core count, insulation, and jacket, so never infer one from the other. Where your documentation uses AWG, follow the catalog's verified correspondence for that terminal rather than a generic conversion.
Sources: Technical applicability · LLT selection guide
Mounting, locking, and gender stay separate
Front-panel, rear-panel, flange, and in-line describe how the interface lands on the machine; pin or socket describes the contact form, so choose them independently. Panel versions need cutout, panel thickness, and locking space checked against the part-number drawing; an in-line joint needs no panel data but does need room for mating travel and bend radius. With self-lock couplings, release the mechanism as designed instead of pulling the cable.
Sources: LLT public connector catalog · Connection and wiring methods · Technical applicability
What the public data proves — and what it does not
IP67 on a selected configuration means dust protection and short-term immersion under defined test conditions — correctly mated and locked, seals intact, specified cable OD sealed at installation. It does not cover long-term immersion or high-pressure washdown, which need separate verification. UV resistance of at least 1,000 hours and salt spray of at least 480 hours are company-provided figures for applicable configurations; request the corresponding reports, and check UL 2238, UL 1977, CE, TÜV, or SAA coverage per certificate, model, and rating.
The public summary lists ratings per configuration, but the 2+6 and 3+8 hybrid groups are not rows in that table, and the summary does not replace formal drawings, temperature-rise verification, or certification documents for your exact part number.
Sources: Technical applicability · IEC 60529 — Degrees of protection provided by enclosures · LLT selection guide · LLT public connector catalog
Send the interface package, then verify with samples
A useful inquiry lets engineering confirm the configuration instead of guessing. Include:
If the mating side already exists, send its drawing or part number and plan a confirmed-sample check before production; appearance similarity is not an interface qualification.
- Per-loop voltage, continuous and peak current, and which circuits are power or signal
- Conductor cross-section per core in mm² or catalog-checked AWG, plus cable jacket OD in mm
- Mounting form, coupling type, contact gender, and panel thickness and cutout where panel-mounted
- Cable length and tolerance, exit direction, tail termination, and branch points
- Environment — rain, immersion, washdown, UV, salt spray, temperature — plus required certification documents
Sources: LLT selection guide · LLT public connector catalog
Source parameters
| Contact count | Rated voltage | Rated current | Maximum conductor cross section |
|---|---|---|---|
| 2 pins | 250 V | 35 A | ≤ 4 mm² |
| 3 contacts | 250 V | 35 A | ≤ 4 mm² |
| 4 contacts | 250 V | 35 A | ≤ 2.5 mm² |
| 5 contacts | 250 V | 20 A | ≤ 1.5 mm² |
| 6 contacts | 250 V | 20 A | ≤ 1.5 mm² |
| 8 contacts | 250 V | 20 A | ≤ 1 mm² |
| 20 pins | 100 V | 5 A | ≤ 0.3 mm² |
| 24 pins | 100 V | 5 A | ≤ 0.3 mm² |
Frequently asked questions
Does the 35 A rating apply to a 2+6 or 3+8 hybrid M25?
No. The 35 A figure belongs to the 2-, 3-, and 4-pin power configurations. The hybrid arrangements rate the power group at 20 A, 250 V and the signal group at 5 A, 100 V on the attached 90° catalog page; confirm the page for your mounting form and part number.
Will two M25 connectors with the same pin count mate?
Not by pin count alone. Interface dimensions, keying, contact gender, locking method, and pin assignment must all match, and face views must be read in the stated viewing direction. Verify against both drawings and, where possible, a confirmed sample pair.
Is IP67 enough for washdown or continuous immersion?
No. IP67 covers short-term immersion under specified test conditions with the connector mated, locked, and sealed to the correct cable. Provide depth, duration, temperature, medium, and cleaning method so engineering can match a configuration with the right verification data.