How to use semiconductor magnetoresistive element
1. Bias magnet
| In general, the semiconductor magnetoresistive element is combined with a bias magnet for use. As shown in the figure at the right, a bias magnet is located at the back face of the semiconductor magnetoresistive element. This combination shall be used for the range where the rate of resistance change is linear and rather larger comparing to the magnetic flux density change, setting the operation point to 0.4T or more using the bias magnet.
In this configuration, if the magnetic media moves in parallel with the semiconductor magnetoresistive element surface, the magnetic flux density on the semiconductor magnetoresistive element changes. The change in the magnetic flux density is taken out as a voltage change.
1) Recommended magnet size for bias magnet
Magnet material: Sm2Co17 (samarium-cobalt magnet)
Magnet size: 4.4 x 4.4 x t5.0 mm (for MS-0020 and MS-0040)
5.5 x 4.4 x t5.0 mm (for MS-0080)
2) Allocation examples of bias magnet
2. Element structure
There are various element structures depending on the application. In general,
the following two structures are widely used. Basically, the structure is formed by
two (four) semiconductor magnetoresistive elements on a chip. On the other hand,
the potential of A (A, B) in non-magnetic field status or in a status in which even
magnetic flux density is applied to all the semiconductor magnetoresistive elements
is called neutral voltage.
Ideally, the neutral voltage is Vc/2 (Vc: control voltage).