KMT36H 360 Angular Sensor * * * * AMR Sensor with 360 capability 3 TDFN outline 2.5x2.5x0.75 mm Three 120 phase-shifted signals Moderate field strength requirements DESCRIPTION The KMT36H is a magnetic field sensor utilizing the anisotropic magneto resistance effect. Therefore the sensor is sensing the magnetic field direction rather than the magnetic field strength. The sensor contains three Wheatstone bridges rotated by 120. A rotating magnetic field (typical strength 25 kA/m in the sensor plane) will result in three sinusoidal output signals with a period of 180, phase shifted by 60 field angle. By use of a modified atan algorithm the field angle can be calculated with high accuracy. As an unique feature, the KMT36H is able to measure full 360 by utilizing an additional magnetic field which is generated by a planar coil that is integrated on the chip. The 180/360 determination is done by a simple sign distinction and may be computed periodically or only once at power up. FEATURES * * * * * APPLICATIONS Ideal for harsh environments due to magnetic sensing principle Contactless absolute angular measurement over 360 Accuracy better than +/- 0.5 Three bridge signals with 120 phase difference 3 Tiny TDFN-housing 2.5 x 2.5 x 0.8 mm KMT36H Rev 5 * Absolute angle measurement * Potentiometer replacement * * Motor motion control Camera positioning * Robotics www.meas-spec.com 1/6 2013-April KMT36H 360 Angular Sensor CHARACTERISTIC VALUES Parameter Condition Symbol Min Typ Max Unit Mechanical dimensions - TDFN Length X 2.5 mm Width Y 2.5 mm Height Z 0.75 mm Length X 4.9 mm Width Y 6.0 mm Height Z Mechanical dimensions - SO8 1.75 mm Operating limits Supply voltage Coil current T = 25 C, H = 25 kA/m VCC 5 12 V ICOIL 20 50 mA Operating temperature -40 +125 C Storage temperature -40 +125 C Parameter Condition Symbol Min Typ Max Unit Applied magnetic field 2), 3) H 15 25 60 kA/m Bridge resistance T = 25 C RB 2.4 3.0 3.6 k max. signal range T = 25 C, H = 25 kA/m V/VCC 18 22 26 mV/V Offset voltage 4) T = 25 C VOFF/VCC -3 +3 mV/V Hysteresis 1) (Repeatability) H = 25 kA/m Hyst 0.15 0.30 deg Accuracy 1) H = 25 kA/m 0.15 0.30 deg TC of amplitude H = 25 kA/m, 5) TCAMP -0.32 %/K TC of bridge resistance 5) TCR +0.32 %/K Coil resistance T = 25 C RCOIL Thermal resistance (junction-ambient) Tamb = 25C, 6) RthJ/A Sensor specification 75 100 280 150 K/W 1) Hysteresis and accuracy are depending nearly inversely proportional on the magnetic field strength. The accuracy is defined as the max. angular difference between actual field angle and measured angle calculated from the third and fifth harmonics of the Fourier spectrum. The hysteresis is defined as angular difference between left and right turn. 2) Generated with reference magnet 67.044 Magnetfabrik Bonn (25 kA/m @ 5.2 mm distance). 3) Minimum value depends on decreasing accuracy, upper limit on decreasing coil influence. Both are no absolute limits, but depend on the given application requirements. 4) Offset voltages measured as difference voltages VO1-VO2, VO2-VO3 and VO3-VO1 in relation to VCC. 5) Reference temperature Tref = -25 C, calculated from values at -25C and +125 C 6) TDFN soldered on standard test PCB, heat sink without solder connection KMT36H Rev 5 www.meas-spec.com 2/6 2013-April KMT36H 360 Angular Sensor BLOCK DIAGRAM 4 VO1 VCOIL+ 5 n. c. VCC VCOIL- GND VO3 8 1 VO2 Figure 1: internal and external connections (TDFN and SO8, Chip) SENSOR OUTLINE The sensitive area is positioned in the center of the housing. Figure 2: SO8 outline KMT36H Rev 5 www.meas-spec.com 3/6 2013-April KMT36H 360 Angular Sensor The sensitive area is positioned in the center of the housing. The bottom plate is designated to be a heat sink. It has no electrical connection to any pin. Figure 3: TDFN outline Pin Assignment for TDFN and SO8: Pin Symbol Function 1 VO2 signal output 2 2 GND negative supply voltage 3 VCC positive supply voltage 4 VO1 signal output 1 5 VCOIL+ positive coil input 6 n. c. not connected 7 VCOIL- negative coil input 8 VO3 signal output 3 Recommended Solder Layout for TDFN: Recommended solder reflow process according to IPC/JEDEC J-STD-020D (Pb-Free Process) TAPE AND REEL PACKAGING INFORMATION DESCRIPTION REEL SIZE UNITS/REEL PIN 1 ORIENTATION KMT36H 7" 3,000 Top-right of sprocket hole side KMT36H/SO 13" 2,500 Top-left of sprocket hole side KMT36H Rev 5 www.meas-spec.com 4/6 NOTE 2013-April KMT36H 360 Angular Sensor TYPICAL PERFORMANCE CURVES 0 90 180 270 0 360 90 180 270 360 field angle in deg field angle in deg V1 = Vo2-Vo1 V2 = Vo3-Vo2 V1(+Icoil) - V1(-Icoil) V3(+Icoil) - V3(-Icoil) V3 = Vo1-Vo3 Figure 3: output voltages V2(+Icoil) - V2(-Icoil) Figure 4: output voltage change due to coil influence SIGNAL EVALUATION 180 EVALUATION As output voltages (V1, V2, V3) we use the three possible differences between the three signal outputs (see fig. 3). At first the true offsets must be subtracted from the raw signals. The field angle in a 180-range then can be calculated in the following manner: Vn 2 +1 1 = arctan Vm 2 3 Using the three possible combinations of output signals (m,n = 1,2 ; 2,3 ; 3,1) three results are obtained, which can be averaged to increase accuracy. Comparing the three results gives additional information about their reliability. 360 EVALUATION In order to distinguish between and +180 two additional measurements are needed: one with positive, the other with negative coil current. In the next step the change in the signals due to the influence of the coil current must be calculated. The sign of these coil-induced output voltage changes gives the 360-information by case differentiation (see figure 4). In principle, this 360 discrimination needs to be computed only once at start up. Nevertheless, it is recommended to check the measurement periodically. KMT36H Rev 5 www.meas-spec.com 5/6 2013-April KMT36H 360 Angular Sensor APPLICATION EXAMPLE Figure 5: An exemplary hardware configuration using an Atmel ATtiny44 microcontroller ORDERING CODE DEVICE PACKAGE MOQ PART NUMBER KMT36H TDFN 2.5 x 2.5 1 Reel G-MRCO-021 KMT36H/SO SO8 (References: JEDEC MS-012) 1 Reel on request ORDERING INFORMATION NORTH AMERICA EUROPE ASIA Measurement Specialties, Inc. 1000 Lucas Way Hampton, VA 23666 United States Phone: +1-800-745-8008 Fax: +1-757-766-4297 Email: sales@meas-spec.com Web: www.meas-spec.com MEAS Deutschland GmbH Hauert 13 D-44227 Dortmund Germany Phone: +49-(0)231-9740-0 Fax: +49-(0)231-9740-20 Email: info.de@meas-spec.com Web: www.meas-spec.com Measurement Specialties China Ltd. No. 26, Langshan Road High-tech Park (North) Nanshan District, Shenzhen 518057 China Phone: +86-755-33305088 Fax: +86-755-33305099 Email: info.cn@meas-spec.com Web: www.meas-spec.com The information in this sheet has been carefully reviewed and is believed to be accurate; however, no responsibility is assumed for inaccuracies. Furthermore, this information does not convey to the purchaser of such devices any license under the patent rights to the manufacturer. Measurement Specialties, Inc. reserves the right to make changes without further notice to any product herein. Measurement Specialties, Inc. makes no warranty, representation or guarantee regarding the suitability of its product for any particular purpose, nor does Measurement Specialties, Inc. assume any liability arising out of the application or use of any product or circuit and specifically disclaims any and all liability, including without limitation consequential or incidental damages. Typical parameters can and do vary in different applications. All operating parameters must be validated for each customer application by customer's technical experts. Measurement Specialties, Inc. does not convey any license under its patent rights nor the rights of others. KMT36H Rev 5 www.meas-spec.com 6/6 2013-April Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: TE Connectivity: G-MRCO-021