HMC1051 / HMC1052 SENSOR PRODUCTS 1 AND 2-AXIS MAGNETIC SENSORS Features · · · · · · · Small 8-Pin SIP or 10-Pin MSOP Packages Two AMR Bridges in One Package Wide Field Range of +/- 6 Gauss 1.0 mV/V/gauss Sensitivity High Accuracy Compassing (Error <0.01°) Low Power Operation Down to 1.8V Patented On-chip Set/Reset Straps Product Description The Honeywell HMC1051Z and HMC1052 are high performance magnetoresistive sensor designs on a single chip. The advantages of these patented chips include perfectly orthogonal two-axis sensing (HMC1052), ultra small size and low power capability in miniature surface mount packages. Each of the magnetoresistive sensors are configured as a 4-element wheatstone bridge to convert magnetic fields to differential output voltages. Capable of sensing fields below 0.1 milligauss, these sensors offer a compact, low cost, high sensitivity and highly reliable solution for low field magnetic sensing. APPLICATIONS HMC1052 Circuit Diagram · Compassing · Navigation Systems · Attitude Reference · Traffic Detection · Medical Devices · Position Sensing Web Sites: www.magneticsensors.com www.ssec.honeywell.com Email: [email protected] 2001 HMC1051/1052 Published Jul 2001 Page 1 Honeywell Solid State Electronics Center 12001 State Highway 55 Plymouth, Minnesota 55441-4799 1-800-323-8295 HMC1051 / HMC1052 SENSOR PRODUCTS SPECIFICATIONS Characteristics Conditions* Min Typ Max Units Vbridge referenced to GND 1.8 2.5 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 1.0 1.2 mV/V/gauss Bridge Offset Offset = (OUT+) – (OUT-) -2.5 +/-1 +2.5 mV/V Bridge Elements Supply Field = 0 gauss after Set pulse Bandwidth Magnetic signal (lower limit = DC) 5 MHz @ 1kHz, Vbridge=5V 50 nV/sqrt Hz Resolution 50Hz Bandwidth, Vbridge=5V 120 mgauss Disturbing Field Sensitivity starts to degrade. Noise Density 20 gauss Use S/R pulse to restore sensitivity. Max. Exposed No perming effect on zero reading 10000 gauss Field Operating Ambient -40 125 °C Ambient, unbiased -55 150 °C Sensitivity TA=-40 to 125°C, Vbridge=5V -3200 -2800 ppm/°C Tempco TA=-40 to 125°C, Ibridge=5mA -600 Bridge Offset TA=-40 to 125°C, No Set/Reset +/-500 TA=-40 to 125°C, With Set/Reset +/-10 Temperature Storage Temperature Tempco Bridge Ohmic -3000 ppm/°C Vbridge=5V, TA=-40 to 125°C 2100 2500 2900 ppm/°C TA=-40 to 125°C 99 101 103 % 0.01 degree Tempco Sensitivity Ratio of X,Y Sensors (HMC1052 Only) X,Y sensor Sensitive direction in X and Y sensors Orthogonality (HMC1052) Linearity Error Best fit straight line +/- 1 gauss 0.1 +/- 3 gauss 0.5 +/- 6 gauss 1.8 3 sweeps across +/-3 gauss 0.06 %FS Repeatability Error 3 sweeps across +/-3 gauss * Tested at 25°C except stated otherwise. 0.1 %FS Hysteresis Error Web Sites: www.magneticsensors.com www.ssec.honeywell.com Email: [email protected] 2001 HMC1051/1052 Published Jul 2001 Page 2 %FS Honeywell Solid State Electronics Center 12001 State Highway 55 Plymouth, Minnesota 55441-4799 1-800-323-8295 HMC1051 / HMC1052 SENSOR PRODUCTS SPECIFICATIONS Characteristics Conditions* Min Typ Max Units Measured from S/R+ to S/R- 3 4 5 ohms 0.1% duty cycle, or less, 0.4 0.5 4 Amp Set/Reset Strap Resistance Current 2msec current pulse Resistance TA=-40 to 125°C 3700 ppm/°C Tempco (available on die) Offset Straps Resistance Measured from OFFSET+ to OFFSET- Offset 12 15 DC Current Constant 18 ohms 10 mA/gauss 3900 ppm/°C Field applied in sensitive direction Resistance TA=-40 to 125°C Tempco * Tested at 25°C except stated otherwise. Pin Configurations (Arrow indicates direction of applied field that generates a positive output voltage after a SET pulse.) HMC1051 Vcc (3) HMC1051Z Pinout HMC1051 HONEYWELL HMC1051Z BRIDGE A BRIDGE B 1 2 3 4 5 6 7 8 Vo+(A) (2) GND Plane (4) Vo-(A) (8) GND1(B) GND2(B) (1) (5) Set/Reset Strap S/R+ (6) S/R(7) HMC1052 HMC1052 Pinout Vcc (5) 10 9 8 7 6 HMC1052 BRIDGE A B BRIDGE B HMC 1052 OUT(10) GND2 GND1 (3) (9) OUT+ (4) OUT(7) GND (1) Set/Reset Strap S/R+ (6) S/R(8) Web Sites: www.magneticsensors.com www.ssec.honeywell.com Email: [email protected] 2001 HMC1051/1052 Published Jul 2001 Page 3 A OUT+ (2) 1 2 3 4 5 Honeywell Solid State Electronics Center 12001 State Highway 55 Plymouth, Minnesota 55441-4799 1-800-323-8295 HMC1051 / HMC1052 SENSOR PRODUCTS Basic Device Operation The HMC1051 and HMC1052 are single-axis and two-axis linear magnetic sensors designed as a Wheatstone bridges formed by a magnetoresistive metal film. With the power supply applied to the bridge, the sensors converts any incident magnetic field in the sensitive direction to a balanced voltage output. The magnetoresistive sensors are made of a nickel-iron (Permalloy) thin-film deposited on a silicon wafer in pattern of resistive strips. In the presence of a magnetic field, a change in the bridge resistive elements causes a corresponding change in voltage across the bridge outputs. In addition to the bridge circuits, the sensors each have two on-chip magnetically coupled straps; the Offset Strap and the Set/Reset Strap. The patented straps eliminate the need for external coils surrounding the bridge elements. The offset strap (available on bare die only) allows for several modes of operation when a direct current is driven through it. These modes are: 1) Subtraction of an unwanted magnetic field, 2) Zero-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. Application Notes Low Cost 2-Axis Compass Very high precision measurements can be made using the HMC1051 and HMC1052 sensors when interfaced with low noise amplifiers and 12 to 16-bit Analog-to-Digital (A/D) converters. For lower resolution (1°) or low cost compass applications, 8 or 10-bit A/D converters may be used with general purpose operational amplifiers. Figure 1 shows a typical 2-axis compassing application using readily available off-the-shelf components. The basic principle of two-axis compassing is to orient the sensor bridge element horizontal to the ground (perpendicular to the gravitational field) and to measure the X and Y analog voltages. With the amplified sensor bridge voltages near-simultaneously converted (measured) to their digital equivalents, the arc-tangent Y/X can be computed to derive the heading information. See the application notes on compassing at Honeywell Magnetic Sensors website (www.magneticsensors.com) for basic principles and detailed application information. Figure 1 U1 Vcc 1nf 2.5 to 3.6v 5.00k 500k LMV358 5.00k U3 500k Vref/2 U2 HMC1052 1nf 500k 1 enable MAX1118 0 data_out clk_in Vref 5.00k LMV358 5.00k 500k Vref/2 .1uf set/reset U4 (2) IRF7507 offset Web Sites: www.magneticsensors.com www.ssec.honeywell.com Email: [email protected] 2001 HMC1051/1052 Published Jul 2001 Page 4 U5 set/reset _set/reset Honeywell Solid State Electronics Center 12001 State Highway 55 Plymouth, Minnesota 55441-4799 1-800-323-8295 HMC1051 / HMC1052 SENSOR PRODUCTS Set/Reset Circuit Notes The set/reset circuit using the IRF7507 dual complementary MOSFETs is shown in Figure 2 with more detail in its Hbridge driven configuration. This configuration is used primarily in battery operated applications were the 0.5 ampere nominal set/reset pulsed currents are best obtained under low voltage conditions. For operation at normal 3.3 or 5 volt logic levels, a single complementary MOSFET pair can be used in a single ended circuit shown in Figure 3. Other complementary MOSFET pairs can be used with the caution that the chosen devices should have less than 0.5 ohms ON resistance and be able to handle the needed supply voltages and set/reset currents. Note that even a 1Hz rate of set/reset function draws an average current of less than 2 microamperes. Vsr 1mf Figure 2 200W Vcc + S - IRF7509(P) G .1mf D set/reset D G Vsr Rset/reset S IRF7509(P) S 4W IRF7509(N) G D _set/reset D G S IRF7509(N) Vsr 1mf Figure 3 200W Vcc + S - IRF7509(P) G .1mf D set/reset D G Rset/reset 4W S IRF7509(N) Magnetic Field Detection For simple magnetic field sensing applications such Magnetic Anomaly Detectors (MADs) and Magnetometers, a similar circuit to the compass application can be implemented. In the example circuit in Figure 4, a HMC1051Z sensor bridge is used with a low voltage capable dual op-amp to detect sufficient intensity of a magnetic field. Uses of the circuit include ferrous object detection such as vehicle detection, a “sniffer” for moderate currents in nearby conductors, and magnetic proximity switching. By using two circuits with a HMC1052, a more omni-directional sensing pattern can implemented. There is nothing special in choosing the resistors for the differential op-amp gain stages other than having like values (e.g. the two 5kW and the 500kW resistors) matched at 1% tolerance or better to reject common-mode interference signals (EMI, RFI). The ratio of the 500kW/5kW resistors sets the stage gain and can be optimized for a specific purpose. The choice of the 5kW value sets impedance loading seen by the sensor bridge network and should be about 4 kilo-ohms or higher for best voltage transfer or matching. Web Sites: www.magneticsensors.com www.ssec.honeywell.com Email: [email protected] 2001 HMC1051/1052 Published Jul 2001 Page 5 Honeywell Solid State Electronics Center 12001 State Highway 55 Plymouth, Minnesota 55441-4799 1-800-323-8295 HMC1051 / HMC1052 SENSOR PRODUCTS U1 Figure 4 Vcc Vcc 500k .1mf 5.0v 5.00k - 10kW pot Threshold Set TLC072 + 5.00k U2 500k - Vcc/2 output TLC072 + LED HMC1051 10kW Vcc * Low ESR Tantalum RLED 200W 1mf* - + 10kW 0.1mf FMMT717 .1uf set/reset set/reset FMMT617 S R 0.1mf offset 10kW Alternating or Direct Current Sensing The HMC1051 and HMC1052 sensors can be utilized in a novel way for moderate to high current sensing applications using a nearby external conductor providing the sensed magnetic field to the bridge. Figure 5 shows a HMC1051Z used as a current sensor with thermistor element performing a temperature compensation function for greater accuracy over a wide range of operational temps. Selection of the temperature compensation (tempco) resistors used depends on the thermistor chosen and is dependant on the thermistor’s %/°C shift of resistance. For best op-amp compatibility, the thermistor resistance should be above about 1000 ohms. The use of a 9-volt alkaline battery supply permits fairly common operational amplifiers such as the 4558 types to be used. Note that the circuit must be calibrated based on the final displacement of the sensed conductor to the measuring bridge. Typically, an optimally oriented measurement conductor can be placed about one centimeter away from the bridge and have reasonable capability of measuring from tens of milliamperes to beyond 20 amperes of alternating or direct currents. See application note AN-209 for the basic principles of current sensing using AMR bridges. U1 Vcc = 9Vdc Figure 5 .1mf 5.00k Rth 500k - RC4458 - RC4558 + + 5.00k Ra tempco network Rb standoff distance output U2 500k Vcc/2 ~ +4.5Vdc HMC1051 Vcc =9Vdc * Low ESR Tantalum 200W 1mf* - + Iac Idc set/reset .1uf set/reset Si1553DL offset U3 Conductor to be Current Measured Web Sites: www.magneticsensors.com www.ssec.honeywell.com Email: [email protected] 2001 HMC1051/1052 Published Jul 2001 Page 6 Honeywell Solid State Electronics Center 12001 State Highway 55 Plymouth, Minnesota 55441-4799 1-800-323-8295 HMC1051 / HMC1052 SENSOR PRODUCTS Three Axis Compassing with Tilt Compensation For full three-axis compassing, the circuit depicted in Figure 6 shows both a HMC1051Z and a HMC1052 used for sensing the magnetic field in three axes. A two-axis accelerometer is also shown to provide pitch and roll (tilt) sensing to correct the three-axis data into to the corrected two-axis heading. The accelerometer can be substituted with a fluidic 2-axis tilt sensor if desired. For lower voltage operation with Lithium battery supplies (2.5 to 3.6Vdc), the Set/Reset circuit should be upgraded from a single IRF7507 to the dual IRF7507 implementation to permit a minimum 1.0 ampere pulse (0.5 ampere per set/reset strap resistance) to both the HMC1052 and HMC1051 sensors. Figure 6 U1 Vcc 1nf 500k 3.3 to 5.0v Vcc 5.00k AN0 LMV324 AN1 5.00k AN2 U3 500k Vcc/2 Vcc/2 HMC1052 1nf AN3 set/reset DO0 500k 5.00k U6 LMV324 5.00k mC 500k Vcc/2 .1uf set/reset with Multiplexed A/D Conv. U4 IRF7507 Vcc offset U5 set/reset .1mf Vcc 500k Two-axis accelerometer U2 5.00k - LMV324 + 5.00k xout DI0 yout DI1 500k Vcc/2 HMC1051 Duty Cycling for Lower Energy Consumption For battery powered and other applications needing limited energy consumption, the sensor bridge and support electronics can be switched “off” between magnetic field measurements. The HMC1051Z and HMC1052 are very low capacitance (Bandwidth > 5MHz) sensor bridges and can stabilize typically before the support electronics can. Also minimizing the quantity of set/reset pulses will save energy too. Figure 7 shows a simple supply switching circuit that can be microprocessor controlled to duty cycle (toggle) the electronics in moderate current (<25mA) applications. Web Sites: www.magneticsensors.com www.ssec.honeywell.com Email: [email protected] 2001 HMC1051/1052 Published Jul 2001 Page 7 Honeywell Solid State Electronics Center 12001 State Highway 55 Plymouth, Minnesota 55441-4799 1-800-323-8295 HMC1051 / HMC1052 SENSOR PRODUCTS Figure 7 Vcc MMBT2907ALT1 To Sensor Circuits Vcc 0.01mf + 10mf - * Used when Vcc = 5.0 volts, jumper when using Vcc = 3.3 volts or less. Gnd mC *MMBD7001LT1 Off On toggle 10kW PACKAGE DRAWING 8-PIN SIP Symbol Millimeters Min Max 1.371 1.728 0.101 0.249 0.355 0.483 9.829 11.253 3.810 3.988 1.270 ref 6.850 7.300 0.381 0.762 Inches x 10E-3 Min Max 54 68 4 10 14 19 387 443 150 157 50 ref 270 287 15 30 Symbol Millimeters Min Max Inches x 10E-3 Min Max A A1 B D E1 e E L1 1.10 0.05 0.15 0.15 0.30 2.90 3.10 2.90 3.10 0.50 BSC 4.75 5.05 0.95 BSC 2.0 5.9 114 114 2.0 BSC 187 37.4 A A1 B D E e H h 43 5.9 11.8 122 122 199 Ordering Information Ordering Number Product HMC1051Z One Axis Magnetic Sensor – SIP8 Package HMC1052 Two Axis Magnetic Sensors – MSOP8 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. Web Sites: www.magneticsensors.com www.ssec.honeywell.com Email: [email protected] 2001 HMC1051/1052 Published Jul 2001 Page 8 Honeywell Solid State Electronics Center 12001 State Highway 55 Plymouth, Minnesota 55441-4799 1-800-323-8295