What are EMI-filtered connectors? 

An EMI-filtered connector is a type of electrical connector that incorporates filtering elements such as capacitors within the connector housing to filter out or block conducted electromagnetic interference (EMI), i.e., filtering out high-frequency noise currents flowing through wires or power/signal cables. Thereby protecting the connected equipment from conducted EMI that could potentially impact electronic equipment or system performance. These connectors allow desired power and control signals to pass while attenuating EMI. The EMI-filtered connector eliminates or suppresses unwanted EMI at the connector interface, thereby protecting any electronic system from these unwanted noises.  

Typically, the EMI-filtered connectors are deployed at the input/output point of the electronic equipment to perform the following two main functions: 

• It prevents EMI and RFI noise generated within the electronic device from being conducted outside via a wiring harness or power cable. i.e., it reduces conducted EMI emission from the electronic device, thereby maintaining signal integrity as well as protecting other connected electronic equipment from the conducted EMI.  
• It also prevents EMI and RFI noise from other electrical and electronic equipment from being conducted into the electronic equipment via wires or power cable. i.e., it enhances electronic equipment immunity against conducted EMI from other devices connected in the same wire or cable.

In short, the EMI-filtered connector is typically connected at the input/output port of the electronic device to prevent conducted EMI (high-frequency noise currents) from entering into or exiting the device, thereby protecting the device from conducted EMI. Note that the wires or conductors will act as an unintentional antenna (emitting radiation) when high-frequency noise current flows.  By blocking or reducing the noise current (conducted EMI) emission from a device, this filtered connector also prevents the radiated emission caused by the noise current flowing through the power conductors or wires. 

The EMC-filtered connectors can use various filtering topologies such as C, LC, CL, PI, and T. These connectors' design utilizes three types of capacitors as filtering elements:  an MLCC (multi-layer ceramic chip) capacitor, a tubular capacitor around the connector pin, and a planar capacitor array. Some connector products integrate high-energy TVS diode technology or MoV’s (metal oxide varistor) components to achieve additional protection against direct lightning strikes or other high-energy impacts, including downstream suppression of: 

• Electromagnetic Pulses (EMP) 
• Electrostatic Discharges (ESD) 
• High-Altitude Electromagnetic Pulse (HEMP) 
• Nuclear Electromagnetic Pulse (NEMP)

EMI filtered connectors are an important tool that helps electronic equipment designers or product manufacturers to meet EMC requirements.  These connectors are available in circular and rectangular formats. They are available to meet standards such as MIL-C-26482, MIL-DTL-83723, MIL-DTL-835515, MIL-DTL-38999, MIL-DTL-24308, and more.  

Key benefits of EMI-filtered connectors: 

• With the filter inside the connector, it saves space (i.e., eliminates additional PCB area required for EMI filter) and reduces product weight. 
• With the filter inside the connector, it enhances system reliability by eliminating the need for additional filtering components and related solder joints. 
• Reduces assembly time by eliminating the need for additional filtering components and related solder joints. 

Applications: 

EMI-filtered connectors are ideal for applications including Aerospace control systems,  Aerospace power systems, Radio communications systems,  Radar systems,  Electronic jamming systems,  Military vision equipment, Avionics systems, Military ground vehicles power distribution systems, Antenna connections, Industrial applications, and more. 

Key specification details of EMI-filtered connectors: 

Filter topology: Represents the filter topology such as C, Pi, and CL used in the filtered connector 

Working voltage: Represents the connector’s operating voltage rating (in V). 

Type: Represents the connector type, such as rectangular/ circular. 

Current rating: Represents the connector’s current rating (in A).