Integrated Compass Sensor HMC6052 Preliminary Information The Honeywell HMC6052 is a 2-axis Magneto-Resistive sensor plus amplifiers and analog support features essential for compassing and low magnetic field sensing. The product is offered in a 14-pin surface mount 3.5mm by 3.5mm LCC package. Two channels of amplified sensor signals with a set switch function allow compass system designers to have a compact, easy to implement solution. Applications for the HMC6052 include electronic compassing, and magnetometry. 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 products provide real solutions you can count on. FEATURES BENEFITS 4 2 Axis AMR Magnetic Sensor (HMC1052) w/ Integrated Amplifiers & Set Circuit Analog Solution Optimized for Compassing. Eliminates 4 Complete Need for External Amplifiers and Most Discrete Components 4 Single Die in a Surface Mount Package (3.5 x 3.5 x 0.8 mm 14-pin LCC) 4 Optimized for Smallest Footprint and Easy Integration 4 Minimal Support Components 4 Only Two Capacitors to Complete the Analog Signal Processing 4 Field Range +/- 2 gauss for Compass Applications in Hand-Held or Hard Iron 4 Optimized Environment 4 Low Voltage Operation (2.5 to 3.6 V) 4 Compatible for Battery Powered Applications 4 Precision Magnetic Field Measurement 4 User’s ADC Resolution Limits the Accuracy of the Outputs 4 Minimal Detectable Field (80 micro-gauss) 4 Permits Accurate Compassing and Magnetic Field Measurement 4 Lead Free Package Construction 4 Complies with Current Environmental Standards (RoHS) HMC6052 HMC6052 SPECIFICATIONS Characteristics Conditions* Min Typ Max Units Supply Voltage Vsupply, Vbridge to GND 2.5 3.0 3.6 Volts Supply Current Vsupply to GND 9 mA Bridge Current A, B bridges Field Range Full scale (FS), Vsupply, Vbridge = 3.0 volts 6 -2.0 mA +2.0 gauss Field Sensitivity Vsupply, Vbridge = 3.0 volts 0.5 V/gauss Zero Field Output Vsupply, Vbridge = 3.0 volts 1.5 volts Load Resistance Applied to OUTA, OUTB 6000 Load Capacitance Applied to OUTA, OUTB - system signal output (lower limit = DC) 1 Bandwidth Noise Floor Vsupply, Vbridge = 3.0V 10,000 - ohms 100 pF kHz 1 mV 0.4 %FS SINL, SINH toggle before measurement Linearity Disturbing Field Vsupply, Vbridge=3.0V, Field +/- 0.5 Oe Sensitivity starts to degrade. 20 Gauss Use set pulse to restore sensitivity. Max. Exposed No perming effect on zero field reading 10000 Gauss Field Operating Ambient -45 120 °C Ambient, Unbiased -55 150 °C -2400 ppm/°C Temperature Storage Temperature Sensitivity -3000 -2700 Tempco Output Voltage ± 500 ppm/°C Tempco Sensitivity Ratio of TA= 0 to 70°C 95 100 105 % 0.01 Degree Max Units Sensors X,Y sensor Sensitive direction in X and Y sensors Orthogonality * Tested at 25°C except stated otherwise. Characteristics Conditions* Min Typ Set Strap Circuit Input Logic Voltage Measured from SIN to GND (Vsupply = 3.0v) Low “0” State 0.3 volts High “1” State 2.5 volts 0 µA Input Logic Current Offset Straps Resistance Measured from OFF+ to OFF- Offset Constant 12 DC Current 15 18 ohms 10 mA/gauss Field applied in sensitive directions Resistance TA= 0 to 70°C 3500 3900 4300 ppm/°C Tempco * Tested at 25°C except stated otherwise. 2 www.honeywell.com HMC6052 OFF+ N/C VBRIDGE OFF- SC- S/R+ Pin Configurations 2 3 4 5 6 1 7 SINL 8 VSR B OUTB A 14 13 12 11 10 9 OUTA GND VSUPPLY SINH SC+ Bottom View Pin Descriptions HMC6052 Pin Name 1 OFF+ 2 N/C 3 VBRIDGE 4 OFF5 SC6 S/R+ 7 SINL 8 VSR 9 SC+ 10 SINH 11 VSUPPLY 12 GND 13 OUTA 14 OUTB www.honeywell.com Description Offset Strap Positive No Connect Positive Voltage Supply (2.7 to 3.6 volts) to Sensor Bridges Offset Strap Negative Set Strap Capacitor Negative Set/Reset Strap Positive (test point) Set Strap Logic Input (normally low) Set Strap Reservoir Capacitor Set Strap Capacitor Positive Set Strap Logic Input (normally high) Positive Voltage Supply (2.7 to 3.6 volts) to Signal Conditioning Negative Voltage Supply and Signal Ground Reference Output Voltage for Sensor A Output Voltage for Sensor B 3 HMC6052 Package Dimensions Symbol A A1 A3 b D D2 E E2 e L N ND NE r aaa bbb ccc Min 0.80 0 0.18 1.90 1.90 0.30 Millimeters Nom 0.90 0.02 0.20 BSC 0.23 3.50 BSC 2.05 3.50 BSC 2.05 0.50 BSC 0.40 14 5 2 Max 1.00 0.05 0.30 2.15 2.15 0.50 b(min)/2 0.15 0.10 0.10 Mounting Considerations Stencil Design and Solder Paste A 4 mil stencil and 100% paste coverage is recommended electrical contact pads. The HMC6052 has been tested successfully with no-clean solder paste. Pick and Place Placement is machine dependant and no restrictions are recommended, and have been tested with mechanical centering. Placement force should be equivalent 1206 SMT components. Reflow and Rework No special profile is required for the HMC6052 and compatible with lead eutectic and lead-free solder paste reflow profiles. Honeywell recommends the adherence to solder paste manufacturer’s guidelines. Irons with a tip temperature no greater than 315°C should be used. Application Notes The HMC6052 Integrated Compass Sensor circuit is composed of two Magneto-Resistive (MR) sensors that sense external magnetic fields and additional analog support circuits for electronic compass functions. Two instrumentation amplifiers follow the sensor wheatstone bridges to measure the differential output signals and provide substantial voltage amplification. A voltage reference is used to center the amplifiers for common zero field bias point. A pair of electronic switch circuits is included, to create a set pulse function using an external capacitor connected to the SC- and SC+ pins. In a quiescent state, the capacitor will be charged to the full supply voltage potential and suddenly discharged in reverse polarity when both SINL and SINH pins flip logic states. The resulting set pulse current flows through the set strap near the sensor bridge re-aligning the magnetic moments on the bridge magneto-resistive elements. This toggling of the set strap circuit is on user demand, or periodically to remove any potential magnetic upsets to the sensors. 4 www.honeywell.com HMC6052 Reference Design The schematic diagram in Figure 1 shows the basic HMC6052 application circuit with a minimum of external components. 3 Vdds = 3V XTAL0 VBRIDGE V+ XTAL1 OUTA G AMR 13 GND AN0 CLK AN1 TXD SERIAL I/O RXD GND GND DO0 µP V+ DO1 DO2 G AMR 4 OFF- 1 OFF+ GND V+ GND Vref NC NC OUTB 14 11 Vss GND 12 OFFSET 8 RS SET VSR 7 SW V+ Vdd +3V MMBT2907 Vdds GND V+ Vdd GND 1µF X7R + 10k Ω GND SINL GND 10 SW S/R+ 6 SC5 SC+ SINH GND 9 0.1µF X7R (2) Figure 1 From Figure 1, the host microprocessor (µP) controls the HMC6052 via digital output port lines DO0 through DO2. The first digital control line (DO0) is normally in a high logic state and briefly pulls down to drive the high-side switch connected to pin 10 (SINH) of the HMC6052. Likewise, DO1 is a reverse logic control line that is normally low and pulls high briefly to drive the low-side switch at pin 7 (SINL) of the HMC6052. Together DO0 and DO1 toggle states to create a “set” pulse through the internal set strap resistance that spirals through the sensor bridge elements. This set pulse creates an intense magnetic field that will re-align the magnetic domains of the magneto-resistive elements to undo the effects of thermal agitation, and any magnetic upset events that might “disturb” the sensors. The frequency of the toggling is the designer’s choice, but typically ranges from once per second to once per day. The external set strap capacitance across pins 5 (SC-) and 9 (SC+) is to be around 0.2uf to 1uf in value, with emphasis on keeping the total capacitor ESR (effective series resistance) below 0.5 ohms to minimize capacitor internal losses while delivering a current spike in excess of 0.5 amperes. The microprocessor also has control of the complete power supplied to the HMC6052 via digital control line DO2 that switches the MMBT2907 bipolar junction transistor, to connect the 3.0-volt system supply voltage to the sensor circuits. By pulling low DO2, the transistor saturates to connect Vdd to Vdds, which are the switched supply connections to VSUPPLY (pin 11) and VBRIDGE (pin 3). With power applied, the HMC6052 internal circuits quickly stabilize to provide accurate magnetic vector voltages at output pins 13 (OUTA) and 14 (OUTB). With near zero magnetic field inputs, OUTA and OUTB should be near half the supply voltage to provide bipolar output voltage values corresponding to the intensity and polarity of the resulting magnetic fields on the sensor bridges. Zero field stimulus to the HMC6052 can be obtained using magnetic shielded containers, or helmholtz coil sets. Toggling the DO2 digital control line is necessary in many applications to reduce the total system current consumption when not taking magnetic field measurements to preserve battery energy reserves. Up to 15mA can be drawn from the www.honeywell.com 5 HMC6052 supply during the sensor circuit’s operation. The supply current can be effectively reduced by “duty cycling” DO2 and making “snapshot” measurements during the sensor’s on time. For example, a 3.0-volt lithium watch battery may have a typical 150mA-hour energy capacity rating. With the reference design drawing about 15mA continuously, only 10 hours of operational time results. By placing the microcontroller and HMC6052 into sleep mode 99% of the time, the total battery life extends to 1000 hours. Even greater efficiencies can be had if the host microprocessor only toggles on DO2 for a few milliseconds, makes the analog to digital conversions of outputs OUTA and OUTB, and then pulls DO2 high to sleep the HMC6052 until the next required measurement update. The analog outputs of the HMC6052 circuit (OUTA, OUTB) are representative voltages proportional to the magnetic field imposed on sensor bridges A and B. The sensor bridges have orthogonal axis of sensitivity and create a two dimensional representation of the magnetic field’s strength and direction. When oriented nearly level with the ground, the outputs can then be used for electronic compassing by sensing the horizontal components of the earth’s magnetic field. Using onboard Analog-to-Digital Converters (ADCs) within the host microprocessor, the digital representations of north-pole magnetic field direction can be related to the host platform (watch, phone, PDA, vehicle, ship, aircraft, etc.). The outputs of the HMC6052 are referenced to approximately half of the supply voltage applied across pins 11 (VSUPPLY) and 12 (GND). With no other errors accounted for, OUTA (pin 13) and OUTB (pin 14) would be close to 1.5 volts with no magnetic field applied (completely shielded) and a supply voltage of 3-volts. If the shielding were removed and a nominal earth’s magnetic field applied of 300 milli-gauss and –100 milli-gauss to sensor bridges A and B respectively, OUTA would move positively from 1.5 volts and OUTB would move negatively from 1.5 volts. Neglecting offset errors and using a nominal sensitivity of 0.5 volts per gauss, OUTA would be at about 1.65 volts and OUTB would be at about 1.45 volts. Using the above example values of earth’s field excitation, a host microprocessor with onboard 10-bit ADCs could provide 1024 increments (or counts) across the nominal zero to 3-volt supply voltage. If count 512 (about 1.5 volts) is referenced as the zero gauss point, the 1.65 and 1.45 volt OUTA and OUTB levels convert to counts 563 and 495 respectively. Without compensating for offset errors and calibration factors, the magnetic vectors for outputs A and B would be 51 and –17 counts with respect to the zero field level count. In electronic compassing, the arctangent (B/A) is computed by the microprocessor, resulting in a heading of about 341 degrees (19 degrees west of magnetic north). For details on offset correction, calibration, and electronic compass heading computation using microprocessors, please visit www.magneticsensors.com, and browse the technical papers and application notes in the applications section. ORDERING INFORMATION Ordering Number HMC6052 Product Integrated Compass Sensor 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 Aerospace Electronics Systems Defense and Space Electronics Systems Honeywell International Inc. 12001 Highway 55 Plymouth, MN 55441 Tel: 800-323-8295 6www.honeywell.com Form #900306 April 2005 ©2005 Honeywell International Inc. www.honeywell.com