＜Current Sensor＞

What is a current sensor?

What is a current sensor?
A current sensor is a sensor that measures the current flowing in a circuit.

Current Detection Methods

Methods for detecting current flow can be classified into resistance detection and magnetic field detection types, as shown below.

[Current Detection Methods and Features]

Resistance Detection Method

The voltage drop across the shunt resistor is converted into current. Although this method is both inexpensive and easy to handle/mount, one significant drawback is the relatively large heat generation due to power loss at the resistor.

Magnetic Field Detection Method

[With Core]
This method measures the current by detecting the magnitude of the magnetic field generated at the core caused by current flowing through the wire. Advantages include non-contact operation along with low power loss, but the mounting area is necessarily large due to the size of the core.

[Without Core]
Current is measured by converting the magnetic field generated around the current flow into a voltage (Hall voltage) using the Hall effect. However, since the voltage generated by the Hall effect is small, the IC includes both a Hall element and amp circuit. The biggest disadvantage with this method is power loss due to current draw into the IC.

MI Current Sensor

In response, ROHM developed a contactless magnetic field detection type current sensor utilizing an MI (Magneto-Impedance) element that eliminates the drawbacks of mounting difficulty (with core) and power loss (without core) that exist with the magnetic field detection types described above.
The MI (Magneto-Impedance) sensor is a next-generation magnetic sensor that takes advantage of the magneto-impedance effects of a special amorphous wire to enable ultra-high sensitivity magnetic detection.
As a result, sensitivity many orders of magnitude greater than Hall sensors is achieved, allowing measurement of minute variations in the magnetic field with extremely high accuracy. This makes it possible to perform contactless, high accuracy current detection (magnetic field detection) without drawing current into the package.

[Comparison of Current Sensor Types (ROHM Study)]

In this way, MI current sensors are capable of measuring current without contact, ensuring minimal power loss while reducing mounting area.