M Series Connectors
Are lightweight triplestart ratchet coupling type connectors designed for avionics, aerospace, Harsh Environment Connectors, security, motorsport and heavy duty applications.
Introduction: The Core of Precision Connectivity
In the realm of mission-critical electronics, the choice of a connector is never “just a detail.” It is the bridge between power and performance. Among the most trusted designs in the world is the self-latching push-pull connector—pioneered and popularized by Lemo. When designing a system, one of the first crossroads an engineer faces is choosing the pin count.
Specifically, the 2 pin lemo connector and the 4 pin lemo connector represent the foundational building blocks of modern instrumentation. Both 2 pin and 4 pin LEMO connectors share the same push-pull locking principle and mechanical quality. The main difference lies in signal capacity and application scope.
- 2 Pin LEMO connectors are typically used for simple power or single-signal transmission.
- 4 Pin LEMO connectors support multiple signals or a combination of power and control signals.
The 2 Pin Lemo Connector: Power and Simplicity
The 2 pin lemo connector is the workhorse of the power world. In a push-pull configuration, having only two pins allows for much larger contact diameters within the same shell size (such as the 0B or 1B series).
- Maximum Current Density: Because there are fewer pins, each pin can handle significantly higher amperage. This makes the 2-pin version ideal for DC power input, battery charging, and high-torque motor drives.
- Mechanical Robustness: Larger pins are physically stronger and more resistant to bending during accidental misalignment or high-vibration environments.
- Wiring Simplicity: With a simple V+ and V- (or Signal and Ground) setup, the 2-pin configuration reduces the risk of wiring errors and simplifies cable assembly (overmolding).
The 4 Pin Lemo Connector: Signal Versatility
As systems become smarter, the demand for data increases. This is where the 4 pin lemo connector (often referred to as the lemo 4 pin connector) shines. It is designed for applications where power alone isn’t enough.
- Differential Signaling: Four pins allow for two twisted pairs, which is essential for noise-canceling signals like RS-422, RS-485, or low-speed Ethernet.
- Hybrid Capability: A common use for the lemo 4 pin connector is “Power + Signal.” Two pins provide VCC and Ground, while the remaining two transmit data (e.g., I2C, SMBus, or simple analog feedback).
- High Pin Density: To fit four pins into the same shell size as a 2-pin, the pins must be thinner. While this reduces the maximum current per pin, it drastically increases the “information density” of the interface.
Technical Specifications Comparison
The following table compares typical values for a 1B series push-pull connector.
| Feature | 2 Pin Lemo Connector | 4 Pin Lemo Connector |
|---|---|---|
| Typical Pin Diameter | 1.3 mm – 1.6 mm | 0.7 mm – 0.9 mm |
| Max Current (per pin) | 10A – 15A | 2A – 7A |
| Rated Voltage (AC/DC) | 250V+ | 150V – 200V |
| Contact Resistance | < 3.5 mΩ | < 5.0 mΩ |
| Wire Gauge (AWG) | 18 – 20 AWG | 22 – 26 AWG |
| Primary Use Case | DC Power, Audio, Battery | Sensors, USB 2.0, RS232 |
Industrial Applications
Medical Devices
In the medical field, reliability is non-negotiable. A 2 pin lemo connector is frequently used for surgical power tools where a high-torque motor requires a steady, high-current flow. Conversely, a lemo 4 pin connector is found in patient monitoring systems, where two pins might power a sensor and two pins return the heart rate or SpO2 data.
Aerospace and Defense
Weight and space are at a premium. Using a 4 pin lemo connector to handle both power and communication for a drone’s gimbal camera saves the weight of an entire second connector and cable assembly.
Industrial Automation & Robotics
Robotic arms utilize the 2 pin lemo connector for heavy-duty actuator power. Meanwhile, the feedback sensors (encoders) that tell the robot its exact position rely on the multi-channel capability of the 4-pin variant to prevent signal crosstalk.
Selection Guide: How to Choose?
When deciding between these two, ask yourself these three questions:
- What is the Total Current Load?
If your device draws more than 7 amps, the 2 pin lemo connector is likely the safer, more thermally efficient choice.
- Is Signal Noise a Factor?
If you are transmitting sensitive data, you need the extra pins of the 4 pin lemo connector for shielding or differential pairs.
- Is Space the Ultimate Constraint?
If you only have room for one port but need both power and data, the 4-pin configuration is your only viable path.
Available LEMO Series for 2 & 4 Pin Configurations
B Series
- Most commonly used
- Compact and versatile
- Suitable for medical and industrial equipment
K Series
- Enhanced sealing
- Suitable for outdoor or harsh environments
S Series
- Higher contact density
- Ideal for compact, high-performance devices
Each series supports both 2 pin and 4 pin layouts with consistent mechanical quality.
FAQ (Frequently Asked Questions)
Can I use a 4 pin lemo connector for a 2-pin application?
Technically, yes. You can bridge pins or leave two unused. However, remember that 4-pin connectors use thinner pins, so you must ensure the current draw doesn’t exceed the lower rating of the 4-pin design.
Are 2-pin and 4-pin connectors cross-mateable?
No. Lemo-style connectors are keyed (using G, A, B, etc., keys) to prevent accidental mismating. A 2-pin plug will not physically fit into a 4-pin socket.
What is the benefit of the “Push-Pull” mechanism over M12 or Threaded connectors?
Speed and safety. The push-pull mechanism allows for blind mating and ensures the connection cannot be broken by pulling on the cable; it only releases when the outer sleeve is retracted.
Does the price vary significantly between 2 and 4 pins?
The cost difference is usually negligible for the connector itself. The real cost difference lies in the cable assembly and the number of conductors in the wire.
Whether you need the high-current capacity of a 2 pin lemo connector or the versatile signaling of a 4 pin lemo connector, Renhotec provides a wide variety of precision-engineered Push-Pull Connectors designed for durability and cost-effectiveness. We specialize in providing high-quality, Lemo-compatible solutions with rapid lead times.
- Download our Full Connector Catalog
- Contact [email protected] for a Custom Quote
- Tel: 0086-027-8129636, 0086-18086610187
As a Product Manager at Renhotec Group (est. 2008), I specialize in providing deep technical insights into connectors, cables, and custom electronic components. Renhotec is a global leader in interconnect solutions, dedicated to manufacturing high-standard products for diverse industries as your trusted technical partner.