Reed Relays

Part Number	Description / PDF	Quantity
HE751A2400 Wickmann / Littelfuse	RELAY REED SPST 500MA 24V	434
HE3621A1250 Wickmann / Littelfuse	RELAY REED SPST 500MA 12V	33
HE3621A0500 Wickmann / Littelfuse	RELAY REED SPST 500MA 5V	10234
HE721A1220 Wickmann / Littelfuse	RELAY REED SPST 500MA 12V	0
HE721A1230 Wickmann / Littelfuse	RELAY REED SPST 500MA 12V	0
HE721C2400 Wickmann / Littelfuse	RELAY REED SPDT 250MA 24V	1954
HE3351A2400 Wickmann / Littelfuse	RELAY REED SPST 1A 24V	1859
HE721R2410 Wickmann / Littelfuse	RELAY REED SPDT 250MA 24V	0
HE3351A1200 Wickmann / Littelfuse	RELAY REED SPST 1A 12V	0
HE3671A2410 Wickmann / Littelfuse	RELAY REED SPST 500MA 24V	0
HE722A1220 Wickmann / Littelfuse	RELAY REED DPST 500MA 12V	0
HE721A2420 Wickmann / Littelfuse	RELAY REED SPST 500MA 24V	0
HE721C2440 Wickmann / Littelfuse	RELAY REED SPDT 250MA 24V	0
HE3321A0440 Wickmann / Littelfuse	RELAY REED SPST 500MA 5V	0
HE721A2415 Wickmann / Littelfuse	RELAY REED SPST 500MA 24V	0
HE721C2420 Wickmann / Littelfuse	RELAY REED SPDT 250MA 24V	0
HE3621A1240 Wickmann / Littelfuse	RELAY REED SPST 500MA 12V	0
HE721C1240 Wickmann / Littelfuse	RELAY REED SPDT 250MA 12V	0
HE3671A0510 Wickmann / Littelfuse	RELAY REED SPST 500MA 5V	0
HE3671A0500 Wickmann / Littelfuse	RELAY REED SPST 500MA 5V	0

Reed Relays

1. Overview

Reed Relays are electromechanical switches comprising a pair of magnetic contacts (reeds) sealed in a glass tube. When a magnetic field generated by a coil actuates the reeds, they flex to make or break an electrical connection. Their hermetic sealing ensures contamination resistance, making them critical in precision applications like automation, telecommunications, and medical devices.

2. Major Types and Functional Classification

Type	Function Features	Application Examples
SPST (Single Pole Single Throw)	Simple on/off switching with one contact pair	Basic circuit control in consumer electronics
SPDT (Single Pole Double Throw)	Three-terminal switch for circuit redirection	Signal routing in test equipment
DPDT (Double Pole Double Throw)	Dual independent circuits with synchronized switching	Motor reversal circuits in industrial machinery
High-Frequency Reed Relays	Optimized for RF/microwave signal integrity	5G base station switching modules
High-Power Reed Relays	Rated for >10A currents with arc suppression	Automotive battery management systems

3. Structure and Components

A typical Reed Relay consists of:

Glass Enclosure: Hermetic seal with inert gas (N₂ or dry air)
Contact Blades: Ferromagnetic Ni-Fe alloy with Au or Rh plating
Coil Assembly: Copper wire wound on ferrite core for magnetic efficiency
Termination Leads: Axial or SMD configurations for PCB mounting

4. Key Technical Specifications

Parameter	Typical Range	Importance
Coil Voltage	3V-48V DC	Determines actuation power consumption
Contact Current	1A-15A	Defines load capacity for circuit design
Operate Time	0.1ms-5ms	Critical for high-speed automation
Insulation Resistance	>10¹²	Ensures signal integrity in medical devices
Life Cycle	10⁷-10⁹ operations	Affects maintenance intervals in industrial systems

5. Application Fields

Major industries include:

Industrial Automation: PLCs, CNC machine controllers
Telecommunications: Optical cross-connect systems, RF test equipment
Medical Devices: MRI scanner circuitry, lab-on-chip analyzers
Automotive: EV charging station contactors, ADAS relay modules
Aerospace: Avionics signal switching in flight control systems

6. Leading Manufacturers and Products

Manufacturer	Representative Product	Key Features
TE Connectivity	KILOVAC EV200	1500VDC isolation for EV charging
Omron Electronics	G6K-2P-Y-DC5	Ultra-compact DPDT with 200mW coil
Fujitsu Component	FBR12W-K-C	10GHz RF performance for 5G testers
Hamlin by TE	HE721-ND	Medical-grade isolation for patient monitors

7. Selection Guidelines

Key considerations:

Load Type: Resistive vs. inductive loads require different contact materials
Switching Speed: Prioritize operate time <1ms for data acquisition systems
Environmental Factors: Select IP67-rated models for automotive under-hood applications
Mounting: Use SMD relays for automated PCB assembly
Cost vs. Longevity: High-endurance models may reduce lifetime maintenance costs

8. Industry Trends

Emerging developments:

Miniaturization: 0402 package reed relays for wearable medical devices
Integration: Smart relays with built-in coil suppression circuits
Material Innovation: Graphene-coated contacts for 10x lifespan improvement
Wireless Control: BLE-enabled reed relay modules for IoT applications
High-Temperature Performance: Relays operational up to 150 C for EV powertrains