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. 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. 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. APPLICATIONS FEATURES • Linear position measurement for process control, • Output voltage proportional to magnetic field Hy across each chip • • Both chips are in the same orientation and chip centres are 3mm apart in Y direction door interlocks, proximity detectors and precision machine tools H-field movement measurement for a magnetic tape recognition • High voltage isolated current measurement up to • Magnetic fields vertical to the chip level Hz are not effective • 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 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 DEVICE MARKING field Hx • ZMX40M PINOUT CONNECTION DIAGRAM AMR chip 1: supply voltage between +Vb1 and -Vb1 output voltage of bridge between +Vout1 and -Vout1 AMR chip 2: supply voltage between +Vb2 and -Vb2 output voltage of bridge between +Vout2 and -Vout2 Top View ISSUE 2 - JUNE 2005 1 SEMICONDUCTORS ZMX40M ABSOLUTE MAXIMUM RATINGS PARAMETER SYMBOL Supply voltage for each sensor chip (1,2) VB LIMIT 12 UNIT V Total power dissipation P TOT 240 mW Operating temperature range T amb -25 to +125 °C Storage temperature range T stg -25 to +125 °C ELECTRICAL CHARACTERISTICS (at Tamb=25°C and HX=3 kA/m unless otherwise stated) PARAMETER SYMBOL MIN TYP MAX UNIT Bridge resistance TEST CONDITIONS R br 1.4 - 2.2 k⍀ Output voltage range V O /V B 12 - 24 mV/V Open circuit sensitivity S 3.0 - 5.0 (mV/V)/ (kA/m) Hysteresis of output voltage V OH /V B - - 50 µV/V Offset voltage V off /V B -1.5 - +1.5 mV/V Operating frequency f max 0 - 1 MHz Temp. coeff. of offset voltage TCV off -3 - +3 (µV/V)/K Tamb= -25 to +125°C Temp. coeff. of bridge resistance TCR br +0.25 +0.3 +0.35 %/K Tamb= -25 to +125°C Temp. coeff. of open circuit sensitivity V B =5V TCS V -0.25 -0.3 -0.35 %/K Tamb= -25 to +125°C Temp. coeff. of open circuit sensitivity I B =3mA TCS I - -0.1 - %/K Tamb= -25 to +125°C VB=const. ORDERING INFORMATION DEVICE REEL SIZE TAPE WIDTH QUANTITY PER REEL ZMX40MT8TA 7” 12mm 1000 units ZMX40MT8TC 13” 12mm 4000 units ISSUE 2 - JUNE 2005 SEMICONDUCTORS 2 ZMX40M TYPICAL APPLICATIONS Magnetic tape scanning (field movement measurement for magnetic tape ruler): The changing voltage peaks in both AMR bridges are used for the tape movement measurement. ZMX40M plus two instrumentation amplifiers for magnetic tape ruler Current sensor (by combining both bridge outputs and a high isolation voltage) This double chip solution with the current loop conductor guarantees good rejection of external fields and a high isolation voltage. ISSUE 2 - JUNE 2005 3 SEMICONDUCTORS ZMX40M ACCESSORIES – Flexible Magnet Material*1 for Length Measuring Systems with ZMX40M type of magnetic structure*2 parameter of length measuring system (flexible magnets 9/28p*3, remanence Br=220mT) (sensor ZMX40M , chip distance s=3mm) pole length (N or S) distance of magnetic period (N/S) middle magnet distance neutral zone length thickness of material gap between tape (or strip) and sensor sine form error sine area of field strength in sensor [mm] [mm] [mm] [mm] [mm] [mm] [%] [kA/m] 90°-condition of length measurement with Arc Tangent Interpolation [tan(α)=] 2,00 2,00 2,00 2,00 2,00 1,20 1,20 1,20 1,20 1,20 6,00 6,00 6,00 6,00 6,00 4,00 4,00 4,00 4,00 4,00 2,40 2,40 2,40 2,40 2,40 12,00 12,00 12,00 12,00 12,00 2,00 2,00 2,00 2,00 2,00 1,20 1,20 1,20 1,20 1,20 6,00 6,00 6,00 6,00 6,00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0,50 0,75 1,00# 1,25 1,50# 0,50 0,75 1,00# 1,25 1,50# 0,50 0,75 1,00# 1,25 1,50# 1,70 1,90 2,00 2,10 2,20 1,20 1,30 1,30 1,30 1,40 3,60 4,10 4,70 5,00 5,20 ±0,07 ±0,05 ±0,03 ±0,02 ±0,02 ±0,04 ±0,03 ±0,02 ±0,02 ±0,02 ±0,40 ±0,25 ±0,12 ±0,09 ±0,08 ±2,6 ±2,7 ±2,7 ±2,4 ±2,3 ±2,7 ±2,5 ±2,4 ±2,6 ±2,3 ±2,5 ±2,7 ±2,5 ±2,6 ±2,7 sin(α)/-cos(α+180°) sin(α)/-cos(α+180°) sin(α)/-cos(α+180°) sin(α)/-cos(α+180°) sin(α)/-cos(α+180°) sin(α)/cos(α+360°) sin(α)/cos(α+360°) sin(α)/cos(α+360°) sin(α)/cos(α+360°) sin(α)/cos(α+360°) sin(α)/cos(α) sin(α)/cos(α) sin(α)/cos(α) sin(α)/cos(α) sin(α)/cos(α) movement area for each tangent segment --- resolution [mm --- µm] ±1,000 --- 10 ±1,000 --- 10 ±1,000 --- 10 ±1,000 --- 10 ±1,000 --- 10 ±0,600 --- 6 ±0,600 --- 6 ±0,600 --- 6 ±0,600 --- 6 ±0,600 --- 6 ±3,000 --- 30 ±3,000 --- 30 ±3,000 --- 30 ±3,000 --- 30 ±3,000 --- 30 type of magnetic structure*2 parameter of length measuring system (flexible magnets 3/24p*4, remanence Br=127mT) (sensor ZMX40M , chip distance s=3mm) pole length (N or S) distance of magnetic period (N/S) middle magnet distance neutral zone length thickness of material gap between tape (or strip) and sensor sine form error sine area of field strength in sensor [mm] [mm] [mm] [mm] [mm] [mm] [%] [kA/m] 90°-condition of length measurement with Arc Tangent Interpolation [tan(α)=] 2,00 2,00 2,00 2,00 2,00 1,20 1,20 1,20 1,20 1,20 6,00 6,00 6,00 6,00 6,00 4,00 4,00 4,00 4,00 4,00 2,40 2,40 2,40 2,40 2,40 12,00 12,00 12,00 12,00 12,00 2,00 2,00 2,00 2,00 2,00 1,20 1,20 1,20 1,20 1,20 6,00 6,00 6,00 6,00 6,00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0,50 0,75 1,00# 1,25 1,50# 0,50 0,75 1,00# 1,25 1,50# 0,50 0,75 1,00# 1,25 1,50# 1,40 1,60 1,60 1,70 1,80 1,00 1,10 1,10 1,20 1,20 2,40 3,20 3,50 3,90 4,20 ±0,20 ±0,13 ±0,10 ±0,07 ±0,06 ±0,12 ±0,06 ±0,05 ±0,04 ±0,03 ±1,40 ±0,65 ±0,45 ±0,33 ±0,23 ±2,6 ±2,6 ±2,7 ±2,6 ±2,6 ±2,7 ±2,4 ±2,3 ±2,3 ±2,3 ±2,7 ±2,5 ±2,7 ±2,7 ±2,6 sin(α)/-cos(α+180°) sin(α)/-cos(α+180°) sin(α)/-cos(α+180°) sin(α)/-cos(α+180°) sin(α)/-cos(α+180°) sin(α)/cos(α+360°) sin(α)/cos(α+360°) sin(α)/cos(α+360°) sin(α)/cos(α+360°) sin(α)/cos(α+360°) sin(α)/cos(α) sin(α)/cos(α) sin(α)/cos(α) sin(α)/cos(α) sin(α)/cos(α) *1 movement area for each tangent segment --- resolution [mm --- µm] ±1,000 --- 10 ±1,000 --- 10 ±1,000 --- 10 ±1,000 --- 10 ±1,000 --- 10 ±0,600 --- 6 ±0,600 --- 6 ±0,600 --- 6 ±0,600 --- 6 ±0,600 --- 6 ±3,000 --- 30 ±3,000 --- 30 ±3,000 --- 30 ±3,000 --- 30 ±3,000 --- 30 Possible source of the flexible magnet accessories, Max Baermann GmbH (51429 Bergisch Gladbach, Germany) (www.max-baermann.de). ISSUE 2 - JUNE 2005 SEMICONDUCTORS 4 ZMX40M *2 According to the application two different forms can be used. a.) magnetic strips for length measuring systems of short distances up to approximately 100mm [flexible plastic material filled with magnetic north-south-parts in a defined raster , for example thickness 1,5mm and width 5mm and magnet pole length 2mm with transverse unilateral magnetization , separably from magnetized foils of the company Max Baermann GmbH , contact address Sales & Applications, Mr. Nass : email [email protected] and phone (+49) (02204) 8309-118 ] b.) magnetic tapes for steel-stabilized length measuring systems of large distances more than 100mm (only the thicknesses x# in above tables) [flexible plastic material without multipolar magnetization by company Max Baermann GmbH , for example, tapes with thickness 1mm and width 5mm and tape length 30m , transverse unilateral multipolar magnetization must be implemented by a suitable third-party] *3 Parameter of TROMAFLEX 928 by company Max Baermann GmbH : flexible plastic bonded ferrite material 9/28p according to DIN 17410 , anisotropic Strontium Ferrite , Br = 220mT , BHc = 170 kA/m , IHc = 280 kA/m , BHmax. = 9,0 kJ/m3 , density = 3,5 g/m3 , middle strain coefficient = 4,49·10-5 m/K to 1m length , operating temperature range = -20°C to +70°C *4 Parameter of TROMAFLEX 324 by company Max Baermann GmbH : flexible plastic bonded ferrite material 3/24p according to DIN 17410 , isotropic Barium Ferrite , Br = 127mT , BHc = 91 kA/m , IHc = 240 kA/m , BHmax. = 3,0 kJ/m3 , density = 3,4 g/m3 , middle strain coefficient = 4,49·10-5 m/K to 1m length , operating temperature range = -20°C to +70°C PRINCIPLES – Length Measurement with Arc Tangent Interpolation for ZMX40M picture : magnetic field representation of magnetic tape (or strip) picture : mathematical principle sensor output 1 (chip 1) : V1 = Hmax • cos (w • 2Π/Λ) = Hmax • sin ((w • 2Π/Λ)+Π/2) sensor output 2 (chip 2) : V2 = Hmax • sin (w • 2Π/Λ) way of movement : w = (Λ/2Π) • arctan (V2/V1) Hmax = func (r , "magnetic structure") r = gap between tape (or strip) and sensor ISSUE 2 - JUNE 2005 5 SEMICONDUCTORS ZMX40M PRINCIPLES – Magnetic Structures of Tape or Strip for ZMX40M The basis of a length measuring system with ZMX40M is a flexible plastic band (tape or strip) filled with magnetic north-south-parts. This magnetic band is moved along under a "ZMX40M - sensor head" or in reverse the head is mobile and the band is rigid. The following variants of magnetic band are possible for use with the ZMX40M. variant 1a : : distance of magnetic period = 2•(b+a) = 12mm : pole width N = b = 2mm : pole width S = b = 2mm : middle magnet distance = b+a = 6mm : neutral zone width = a = 4mm : 90°-condition s = (b+a) / 2 : processing tan (α) = sin (α) / cos (α) variant 1b : : distance of magnetic period = 2•(b+a) = 12mm : pole width N = b = 5mm : pole width S = b = 5mm : middle magnet distance = b+a = 6mm : neutral zone width = a = 1mm : 90°-condition s = (b+a) / 2 : processing tan (α) = sin (α) / cos (α) variant 1c ...... etc. ...... etc. (with different relations b to a) variant 2 : : distance of magnetic period = 2•b = 12mm : pole width N = b = 6mm : pole width S = b = 6mm : middle magnet distance = b = 6mm : neutral zone width = a = 0 : 90°-condition s = b / 2 : processing tan (α) = sin (α) / cos (α) variant 3 : : distance of magnetic period = 2•b = 4mm : pole width N = b = 2mm : pole width S = b = 2mm : middle magnet distance = b = 2mm : neutral zone width = a = 0 : (90°+180°)-condition s = (b / 2)+b : processing tan (α) = sin (α) / cos (α) = sin (α) / -cos (α+180°) ISSUE 2 - JUNE 2005 SEMICONDUCTORS 6 ZMX40M ISSUE 2 - JUNE 2005 7 SEMICONDUCTORS ZMX40M PACKAGE OUTLINE PACKAGE DIMENSIONS Millimeters Inches Millimeters DIM Inches DIM Min Max Typ. Min Max Typ. Min Max Typ. Min Max Typ. A - 1.7 - - 0.067 - e1 - - 4.59 - - 0.1807 A1 0.02 0.1 - 0.008 0.004 - e2 - - 1.53 - - 0.0602 b - - 0.7 0.0275 He 6.7 7.3 - 0.264 0.287 - c 0.24 0.32 - D 6.3 6.7 - 0.009 0.013 - Lp 0.9 - - 0.035 - - 0.248 0.264 - ␣ - 15° - - 15° - - - © Zetex Semiconductors plc 2005 Europe Americas Asia Pacific Corporate Headquarters Zetex GmbH Streitfeldstraße 19 D-81673 München Germany Zetex Inc 700 Veterans Memorial Hwy Hauppauge, NY 11788 USA Zetex (Asia) Ltd 3701-04 Metroplaza Tower 1 Hing Fong Road, Kwai Fong Hong Kong Zetex Semiconductors plc Zetex Technology Park Chadderton, Oldham, OL9 9LL United Kingdom Telefon: (49) 89 45 49 49 0 Fax: (49) 89 45 49 49 49 [email protected] Telephone: (1) 631 360 2222 Fax: (1) 631 360 8222 [email protected] Telephone: (852) 26100 611 Fax: (852) 24250 494 [email protected] Telephone (44) 161 622 4444 Fax: (44) 161 622 4446 [email protected] 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 2 - JUNE 2005 SEMICONDUCTORS 8