ZMX40M
DUAL MAGNETIC FIELD SENSOR
DESCRIPTION
This device is a special tangential field difference
sensor with two AMR (Anisotropic Magneto-Resistive)
bridges for field movement measurements or field
comparative measurements.
The ZMX40M contains two extremely sensitive magnetic
sensor chips, mounted parallel to each other in an SM8
package, employing the magneto-resistive effect of thin
film permalloy. It allows the measurement of magnetic
fields or the detection of magnetic parts. The sensors each
consist of a chip covered with thin film permalloy stripes
which form a Wheatstone bridge, whose output voltage is
proportional to the magnetic field component Hy. A field
Hx, which is perpendicular to Hy, is necessary to suppress
the hysteresis and to bias the sensors into the linear
region. This field Hx is provided by an internal permanent
magnet.
The chips are mounted in the package 3mm apart. If a
magnet travels horizontally above the sensor, each chip
will give an output which will peak as the magnet passes
above it and the two peaks will be spatially separated by
3mm.
When the two peaks are the same amplitude, the magnet
must be mid-way between the two chips. Therefore this
double sensor can be used to measure position of, for
example, a wheel tooth very accurately for automotive
and machine-tool applications. With calibration to allow
for the tolerances on the bridge outputs being slightly
different, the ZMX40M has been used in machine tool
applications to resolve distances down to 30µm. By
comparing the two outputs and adding some hysteresis,
a large-geometry magnetic tape reader (for example for a
magnetic tape ruler) can be made. By combining both
bridge outputs a current sensor can be also made by
adding an external current loop over or under the
ZMX40M. This loop is outside the package and therefore
provides excellent galvanic isolation.
APPLICATIONS
FEATURES
•
Output voltage proportional to magnetic field Hy
across each chip
•
Linear position measurement for process control,
•
door interlocks, proximity detectors and precision
machine tools
H-field movement measurement for a magnetic
tape recognition
many amps range by using a suitable current loop
over or under the IC
Detection of rotating magnets in the presence of a
disturbing field by comparisons of maximum
values of individual sensors
•
Both chips are in the same orientation and chip
centres are 3mm apart in Y direction
•
Magnetic fields vertical to the chip level Hz are not
effective
•
High voltage isolated current measurement up to
•
•
Disturbing fields Hx up to 30 kA/m are allowed
•
Extremely small chip distance from the top side of
package for accurate measurement
•
Internal magnet each chip for creation of auxiliary
field Hx
DEVICE MARKING
•
ZMX40M
PINOUT
CONNECTION DIAGRAM
AMR chip 1:
supply voltage between +Vb1 and -Vb1
output voltage of bridge between
+V
out
1 and -V
out
1
AMR chip 2:
supply voltage between +Vb2 and
-Vb2 output voltage of bridge between
+V
out
2 and -V
out
2
Top View
ISSUE 1 - MARCH 2004
1
SEMICONDUCTORS
ZMX40M
PACKAGE OUTLINE
PACKAGE DIMENSIONS
Millimeters
DIM
Min
A
A1
b
c
D
-
0.02
-
0.24
6.3
Max
1.7
0.1
-
0.32
6.7
Typ.
-
-
0.7
-
-
Min
-
Max
0.067
Typ.
-
-
0.0275
-
-
e1
e2
He
Lp
Inches
DIM
Min
-
-
6.7
0.9
-
Max
-
-
7.3
-
15°
Typ.
4.59
1.53
-
-
-
Min
-
-
Max
-
-
Typ.
0.1807
0.0602
-
-
-
Millimeters
Inches
0.008 0.004
-
-
0.264 0.287
0.035
-
-
15°
0.009 0.013
0.248 0.264
© Zetex plc 2004
Europe
Zetex GmbH
Streitfeldstraße 19
D-81673 München
Germany
Telefon: (49) 89 45 49 49 0
Fax: (49) 89 45 49 49 49
europe.sales@zetex.com
Americas
Zetex Inc
700 Veterans Memorial Hwy
Hauppauge, NY 11788
USA
Telephone: (1) 631 360 2222
Fax: (1) 631 360 8222
usa.sales@zetex.com
Asia Pacific
Zetex (Asia) Ltd
3701-04 Metroplaza Tower 1
Hing Fong Road, Kwai Fong
Hong Kong
Telephone: (852) 26100 611
Fax: (852) 24250 494
asia.sales@zetex.com
Corporate Headquaters
Zetex plc
Fields New Road, Chadderton
Oldham, OL9 8NP
United Kingdom
Telephone (44) 161 622 4444
Fax: (44) 161 622 4446
hq@zetex.com
These offices are supported by agents and distributors in major countries world-wide.
This publication is issued to provide outline information only which (unless agreed by the Company in writing) may not be used, applied or reproduced
for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. The Company
reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service.
For the latest product information, log on to
www.zetex.com
ISSUE 1 - MARCH 2004
5
SEMICONDUCTORS
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