Littelfuse Hamlin Magnetic/Reed Switches (Radial Leaded & Surface Mount)

The Littelfuse Hamlin Magnetic/Reed Switch has two ferromagnetic blades (reeds) contained within a tubular glass envelope that is hermetically sealed at each end. The contacts on each reed blade have a thin layer of precious metal material deposited on them. There is usually nitrogen gas on the inside of the glass envelope to eliminate the presence of oxygen and ensure that the contacts will not oxidize. Hamlin Reed Switches are activated by a permanent magnet or an electromagnet. The magnetic field combination is commonly known as the “magnetic circuit", these are very popular for battery-powered applications. Because Reed switches can switch AC or DC loads, they are a popular choice for digital on/off applications.

The relative stiffness of the reed blades, along with the small gap and overlap between the two contacts, controls the sensitivity of the Hamlin Reed Switch. The sensitivity of the switch is the amount of magnetic field that is required to actuate the contact into an open or closed mode. It is measured in units of ampere-turns (AT). Most High Power Reed Switches have a sensitivity range of 10–30 AT, where 10 AT is more sensitive than 30 AT

Features

  • Can be used as changeover or normally closed contact
  • Capable of switching global mains voltage
  • Excellent for switching micro-controller logic level loads
  • Hermetically sealed switch contacts are not affected by and have no effect on their external environment
  • Zero operating power is required for contact closure

Applications

  • Gas and water metering: 
    • Pulse counting
    • Tamper switch
  • Other electronic equipment:
    • Electronic shelf labeling
    • Equipment for hazardous environments
    • Fitness equipment
    • Solar trackers
  • Safety and security: 
    • Electronic door locks
    • Smoke alarms
    • Window/door sensors
  • White goods and small home appliances: 
    • Fluid level
    • Position sensors

Technical Specifications

Series Switching Power
(W)
Switching Voltage
(V)
Break down
Voltage per MIL-STD-202
(Vdc - min.)
Switching
Current
(A)
Contact
Resistance
(Ω)
Operating
Temperature
(°C)
Magnetic Sensitivity
(AT)
Data
sheets
FLEX-14 10 200 Vdc, 140 Vac 250 0.5 Adc, 0.35 Aac 0.1 -40 to +125 10-30 FLEX-14
HA15-2 20 200 Vdc, 265 Vac 400 to 
450
0.5 Adc, 0.35 Aac 0.1 -20 to +125 22-33 HA15-2
MDCG-4 10 200 Vdc, 140 Vac 250 0.5 Adc, 0.35 Aac 0.1 -40 to +125 12-38 MDCG-4
MDRR-DT 5 175 Vdc, 120 Vac 200 0.25 Adc, 0.18 Aac 0.1 -40 to +125 15-30 MDRR-DT
MDSR-10 10 200 Vdc, 140 Vac 250 0.5 Adc, 0.35 Aac 0.12 -40 to +125 10-25 MDSR-10
MDSR-7 10 200 Vdc, 140 Vac 250 0.5 Adc, 0.35 Aac 0.1 -40 to +125 10-25 MDSR-7
MITI-3V1 10 170 Vdc, 120 Vac 175 0.25 Adc, 0.18 Aac 0.15 -40 to +125 6-10 MITI-3V1
MLRR-3 20 200 Vdc, 140 Vac 250 1.0 Adc, 0.7Aac 0.1 -40 to +125 17-38 MLRR-3
MLRR-4 20 200 Vdc, 140 Vac 250 1.0 Adc, 0.7Aac 0.1 -40 to +125 17-38 MLRR-4
MDSM-10 10 200 Vdc, 140 Vac 250 0.5 Adc, 0.35 Aac 0.12 -40 to +125 10-25 MDSM-10
MDSM-4 10 200 Vdc, 140 Vac 250 0.5 Adc, 0.35 Aac 0.1 -40 to +125 12-38 MDSM-4
MDSM-DT 5 175 Vdc, 120 Vac 200 0.25 Adc, 0.18 Aac 0.1 -40 to +125 15-30 MDSM-DT
MISM-3V1 10 170 Vdc, 120 Vac 175 0.25 Adc, 0.18 Aac 0.15 -40 to +125 6-10 MISM-3V1