Browse Prior Art Database

Dual Slope Magnetoresistive Current Sensor

IP.com Disclosure Number: IPCOM000088772D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Feng, JS: AUTHOR

Abstract

In certain applications, it is required to detect a threshold of about 10 mA while the maximum current may reach 100-200 mA. In order to minimize the requirements on the additional electronics, it is desirable in these cases to have a current transducer with its greatest sensitivity in the range of 0-10 mA and a lower sensitivity to higher currents.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 87% of the total text.

Page 1 of 2

Dual Slope Magnetoresistive Current Sensor

In certain applications, it is required to detect a threshold of about 10 mA while the maximum current may reach 100-200 mA. In order to minimize the requirements on the additional electronics, it is desirable in these cases to have a current transducer with its greatest sensitivity in the range of 0-10 mA and a lower sensitivity to higher currents.

Although it is possible to modify the response of a magnetoresistive (MR) current sensor to give this characteristic by means of external electronic parts, this is a method of incorporating this feature in the response of the sensor itself.

The method, as applied in Fig. 1, consists simply of adding a thin layer 10 of high permeability magnetic material to the current conductors 11 of a normal MR current sensor 12. At low currents this increases the sensitivity of the device roughly by a factor of two. If "keeper" layer 10 is thin enough, it soon becomes magnetically saturated, and it no longer enhances the sensitivity of the transducer.

Thus, having a thin keeper layer results in a device with two different sensitivities, and with its greatest sensitivity to the lowest currents. This dual sensitivity is illustrated schematically in Figs. 2A-C. Fig. 2A shows a normal response curve without a layer 10. Fig. 2B shows a response curve with a thick layer 10. Fig. 2C shows a response curve with a thin layer 10.

This device is useful in applying the MR sensor in sensing the loop cu...