2-Axis Magnetic Sensor HMC1042L The Honeywell HMC1042L is a high-performance, two-axis magneto-resistive sensor. It is designed for magnetic compass applications with capability of 0.2 degree accuracy. Stand alone or by adding the companion HMC1041Z sensor, precision two and three-axis magnetometry or compassing solutions are enabled. Pin compatible with the HMC1052L; this miniature, low cost solution is easy to assemble for high volume, cost effective OEM designs. Applications for the HMC1042L include Compassing, Navigation Systems, Magnetometry, and Magnetic Anomaly Detection. The HMC1042L utilizes Honeywell’s Anisotropic Magnetoresistive (AMR) technology that provides advantages over coil based magnetic sensors. They are extremely sensitive, low field, low hysteresis, solid-state magnetic sensors designed to measure direction and magnitude of Earth’s magnetic fields, from tens of micro-gauss to 6 gauss. Honeywell’s Magnetic Sensors are among the most sensitive and reliable low-field sensors in the industry. Honeywell continues to maintain product excellence and performance by introducing innovative solid-state magnetic sensor solutions. These are highly reliable, top performance products that are delivered when promised. Honeywell’s magnetic sensor solutions provide real solutions you can count on. FEATURES BENEFITS 4 Two-Axis Precision Sensors Orthogonality and ±0.2%FS/gauss Cross Axis 4 Near-Perfect Performance 4 Miniature Surface Mount Two-Axis Magnetic Sensors (3mm x 3mm QFN) Size for Low Profile Sensing Applications and Mounting, 4 Small Compatible with High Speed SMT Assembly 4 Low Voltage Operations (1.8V) 4 Compatible for Battery Powered Applications 4 Low Cost 4 Designed for High Volume, Cost Effective OEM Designs 4 Available in Tape & Reel Packaging 4 High Volume OEM Assembly 4 Lead Free Package Construction 4 Complies with Current Environmental Standards 4 4-Element Wheatstone Bridge 4 Low Noise Passive Element Design 4 Wide Magnetic Field Range (+/-6 Oe) 4 Sensor Can Be Used in Strong Magnetic Field Environments 4 Patented Offset and Set/Reset Straps 4 Stray Magnetic Field Compensation HMC1042L SPECIFICATIONS Characteristics Conditions* Min Typ Max Units Vbridge referenced to GND 1.8 3.0 20 Volts Resistance Bridge current = 1mA 800 1000 1500 ohms Field Range Full scale (FS) – total applied field -6 +6 gauss Sensitivity Set/Reset Current = 0.5A 0.8 1.2 mV/V/gauss Resolution 1 kHz bandwidth, Vbridge = 5.0 volts Bridge Elements Supply Bridge Offset Bandwidth Disturbing Field Max. Exposed Field Operating Temperature Storage Temperature Humidity Sensitivity Tempco Offset = (OUT+) – (OUT-) Field = 0 gauss after Set pulse -1.25 Magnetic signal (lower limit = DC) Sensitivity starts to degrade. Use S/R pulse to restore sensitivity. 1.0 0.16 milli-gauss (RMS) 1.44 milli-gauss (pk – pk) ±0.5 +1.25 5 mV/V MHz 20 gauss No perming effect on zero reading 10000 gauss Ambient -40 125 °C Ambient, unbiased -55 150 °C 85 % -2400 ppm/°C Tested at 85°C TA= -40 to 125°C, Vbridge=5V -3000 -2700 Bridge Offset Tempco TA= -40 to 125°C, No Set/Reset TA= -40 to 125°C, With Set/Reset Bridge Ohmic Tempco Vbridge=5V, TA= -40 to 125°C Cross-Axis Sensitivity Cross field = 0.5 gauss, Happlied = ±3 gauss ±0.2% Best fit straight line ± 1 gauss ± 3 gauss ± 6 gauss 0.1 0.5 1.8 Hysteresis Error 3 sweeps across ±3 gauss 0.06 %FS Repeatability Error 3 sweeps across ±3 gauss 0.1 %FS 23.4 milli-grams Linearity Error ±500 ±10 2100 Weight 2500 ppm/°C 2900 ppm/°C %FS/gauss %FS Set/Reset Strap Resistance Current Resistance Tempco Measured from S/R+ to S/R- 3 4.5 6 ohms 0.1% duty cycle, or less, 2µsec current pulse 0.4 0.5 4 Amp TA=-40 to 125°C 3300 3700 4100 ppm/°C Measured from OFFSET+ to OFFSET- 12 15 18 ohms Offset Straps Resistance Offset Constant DC Current, Field applied in sensitive direction Resistance Tempco TA=-40 to 125°C * Tested at 25°C except stated otherwise. 2 10 3500 3900 mA/gauss 4300 ppm/°C www.honeywell.com HMC1042L SCHEMATIC DIAGRAM VB OUT(A) OUT+ (A) OUT(B) GND1 GND2 (A) (A) OFF(A,B) OUT+ (B) GND1 GND2 (B) (B) OFF+ (A,B) S/R(A,B) S/R+ (A,B) PIN CONFIGURATIONS (Arrow indicates direction of applied field that generates a positive output voltage after a SET pulse.) BOTTOM VIEW NC 9 S/R+ 8 GND2 (B) 7 OFF- 6 NC 5 10 11 NC 12 B A 4 VB www.honeywell.com OUT(B) S/R- 3 2 13 GND1 (A) 14 OUT(A) 15 GND1 (B) 16 OUT+ (B) Pin Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Function GND2 (A) OFF+ OUT+ (A) VB NC OFFGND2 (B) S/R+ NC OUT- (B) S/RNC GND1 (A) OUT- (A) GND1 (B) OUT+ (B) 1 OUT+ OFF+ GND2 (A) (A) 3 HMC1042L PACKAGE OUTLINES PACKAGE DRAWING HMC1042L (16-PIN LCC, dimensions in millimeters) Symbol A A1 A3 b D D2 E E2 e L N ND NE r aaa bbb ccc Millimeters min max 0.80 1.00 0 0.05 0.20 REF 0.18 0.30 3.00 BSC 1.55 1.80 3.00 BSC 1.55 1.80 0.50 BSC 0.30 0.50 16 4 4 B(min)/2 0.15 0.10 0.10 The following is the recommend printed circuit board (PCB) footprint for the HMC1042L. All dimensions are nominal and in millimeters. NOMINAL PAD SIZE 0.40 X 0.23 MM 0.05 0.20 NOMINAL LAND SIZE 0.65 X 0.28MM 4 www.honeywell.com HMC1042L Stencil Design and Solder Paste A 4 mil stencil and 100% paste coverage is recommended for the electrical contact pads. The HMC1042L has been tested successfully with no-clean solder paste. BASIC DEVICE OPERATION The Honeywell HMC1042L magnetoresistive sensors are Wheatstone bridge devices to measure magnetic fields. With power supply applied to the bridges, the sensors convert any incident magnetic field in the sensitive axis directions to a differential voltage output. In addition to the bridge circuit, the sensor has two on-chip magnetically coupled straps; the offset strap and the set/reset strap. These straps are Honeywell patented features for incident field adjustment and magnetic domain alignment; and eliminate the need for external coils positioned around the sensors. The straps are common in effect to both bridges. The magnetoresistive sensors are made of a nickel-iron (Permalloy) thin-film deposited on a silicon wafer and patterned as a resistive strip element. In the presence of a magnetic field, a change in the bridge resistive elements causes a corresponding change in voltage across the bridge outputs. These resistive elements are aligned together to have a common sensitive axis (indicated by arrows on the pinouts) that will provide positive voltage change with magnetic fields increasing in the sensitive direction. Because the output only is in proportion to the one-dimensional axis (the principle of anisotropy) and its magnitude, additional sensor bridges placed at orthogonal directions permit accurate measurement of arbitrary field direction. The combination of sensor bridges in two and three orthogonal axis permit applications such as compassing and magnetometry. The offset strap allows for several modes of operation when a direct current is driven through it. These modes are: 1) Subtraction (bucking) of an unwanted external magnetic field, 2) null-ing of the bridge offset voltage, 3) Closed loop field cancellation, and 4) Auto-calibration of bridge gain. The set/reset strap can be pulsed with high currents for the following benefits: 1) Enable the sensor to perform high sensitivity measurements, 2) Flip the polarity of the bridge output voltage, and 3) Periodically used to improve linearity, lower cross-axis effects, and temperature effects. Offset Strap The offset strap is a spiral of metallization that couples in the sensor element’s sensitive axis. The offset strap measures nominally 15 ohms, and requires 10mA for each gauss of induced field. The straps will easily handle currents to buck or boost fields through the ±6 gauss linear measurement range, but designers should note the extreme thermal heating on the die when doing so. With most applications, the offset strap is not utilized and can be ignored. Designers can leave one or both strap connections (Off- and Off+) open circuited, or ground one connection node. Do not tie both strap connections together to avoid shorted turn magnetic circuits. Set/Reset Strap The set/reset strap is another spiral of metallization that couples to the sensor elements easy axis (perpendicular to the sensitive axis on the sensor die. Each set/reset strap has a nominal resistance of 4.5 ohms with a nominal required peak current of 500mA for reset or set pulses. With rare exception, the set/reset strap must be used to periodically condition the magnetic domains of the magneto-resistive elements for best and reliable performance. A set pulse is defined as a positive pulse current entering the S/R+ strap connection. The successful result would be the magnetic domains aligned in a forward easy-axis direction so that the sensor bridge’s polarity is a positive slope with positive fields on the sensitive axis result in positive voltages across the bridge output connections. A reset pulse is defined as a negative pulse current entering the S/R+ strap connection. The successful result would be the magnetic domains aligned in a reverse easy-axis direction so that bridge’s polarity is a negative slope with positive fields on the sensitive axis result in negative voltages across the bridge output connections. Typically a reset pulse is sent first, followed by a set pulse a few milliseconds later. By shoving the magnetic domains in completely opposite directions, any prior magnetic disturbances are likely to be completely erased by the duet of pulses. For simpler circuits with less critical requirements for noise and accuracy, a single polarity pulse circuit may be employed www.honeywell.com 5 HMC1042L (all sets or all resets). With these uni-polar pulses, several pulses together become close in performance to a set/reset pulse circuit. Figure 1 shows a quick and dirty manual pulse circuit for uni-polar application of pulses to the set/reset strap. Iset Rsr 3.0 5 volts Figure 1 Manual Set Pulse Circuit ORDERING INFORMATION Ordering Number Product HMC1042L Two Axis Magnetic Sensor HMC1042L T/R 3k Tape and Reel 3k pieces/reel HMC1042L Cut Tape Cut Tape FIND OUT MORE For more information on Honeywell’s Magnetic Sensors visit us online at www.magneticsensors.com or contact us at 800-323-8295 (763-954-2474 internationally). The application circuits herein constitute typical usage and interface of Honeywell product. Honeywell does not warranty or assume liability of customerdesigned circuits derived from this description or depiction. Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others. U.S. Patents 4,441,072, 4,533,872, 4,569,742, 4,681,812, 4,847,584 and 6,529,114 apply to the technology described Honeywell 12001 Highway 55 Plymouth, MN 55441 Tel: 800-323-8295 www.honeywell.com/magneticsensors 6 Form #900340 November 2006 ©2006 Honeywell International Inc. www.honeywell.com