Crocus Technology – CTSR400C Series: Magnetic Sensor as a Switch

The Crocus CTSR400C series is a family of magnetic switches designed for sensing a wide range of magnetic fields. The advantages of the CTSR400C series include high magnetic sensitivity, no bias current, low power consumption, flexible supply voltage, small form factor, and low cost.
The Crocus series of magnetic switches is composed of multiple magnetic tunnel junctions (MTJs) made of magnetic thin films. The MTJ cell is constructed of two magnetic layers separated by a thin oxide which serves as a tunnel oxide. One of the two magnetic layers has a fixed magnetic orientation and it is called reference layer. The other magnetic layer, called sensing layer, has flexibility of changing orientation in the presence of magnetic field, leading to the change of the sensor resistance. Thus, the sensor acts as a magnetic switch whereby it shows high resistance when magnetic field is absent and low resistance when magnetic field is present.

Crocus magnetic switches provide high stability as well as highly reliable performance over a wide range of operating temperatures and voltage supply.


  • High sensitivity
  • High temperature operation
  • High frequency performance
  • High stability
  • Low power


  • Switching open/close (off/on)
  • Latching
  • Proximity switching
  • Rotation and speed
  • Position sensing
Pin Name Pin Number Note
R+ 1
R- 2
DNU 3 Do not use
Switching from high to low resistance and back to high

Switching from high to low resistance and back to high

Switch as two-terminal device

Switch as two-terminal device

CTSR420C – IS2/Basic Parameters

ParameterDescription Min Typical Max Unit
Supply voltage*5 15 V
Output resistance: ON Rl 9 10 12
Output resistance: OFF Rh 16 20 26
Max. current1 mA
Operating temperature -40 +85 °C
Operating point (BOP) 5 mT
Release point (BRP)0.5 mT
Hysteresis (BHYS) 4.5 mT
Switching speed: ON 600 ns
Switching speed: OFF 600 ns
Max. exposed field 1 T
Package SOT23 3 x 2.6 mm

*Note: This product also works with voltage supply of 1.2V and 3V