HMC1052

HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS 1, 2 AND 3-AXIS MAGNETIC SENSORS Features x x x x x Miniature Surface-Mount Packages Wide Field Range of ± 6 Gauss 1.0 mV/V/gauss Sensitivity Low Power Operation Down to 1.8V Patented On-chip Set/Reset and Offset Straps Product Description The Honeywell HMC1051, HMC1052 and HMC1053 are high performance magnetoresistive sensor designs on a single chip (HMC1051, HMC1052) or two chips (HMC1053). The advantages of these patented chips include orthogonal two-axis sensing (HMC1052), ultra small size and low cost in miniature surface mount packages. Each of the magneto-resistive sensors are configured as a 4-element wheatstone bridge to convert magnetic fields to differential output voltages. Capable of sensing fields down to 120 micro-gauss, these sensors offer a compact, high sensitivity and highly reliable solution for low field magnetic sensing. APPLICATIONS HMC1052 Circuit Diagram x Compassing x Navigation Systems x Attitude Reference x Traffic Detection x Medical Devices (9) x Position Sensing Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 1 (3) HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS SPECIFICATIONS Characteristics Conditions* Min Typ Max Units Vbridge referenced to GND 1.8 3.0 20 Volts Resistance Bridge current = 10mA 800 1000 1500 ohms Operating Ambient -40 125 °C Ambient, unbiased -55 150 °C 85 % +6 gauss Bridge Elements Supply Temperature Storage Temperature Humidity Field Range Tested at 85°C Full scale (FS) – total applied field Linearity Error -6 Best fit straight line ± 1 gauss 0.1 ± 3 gauss 0.5 ± 6 gauss 1.8 Hysteresis Error 3 sweeps across ±3 gauss 0.06 %FS Repeatability Error 3 sweeps across ±3 gauss 0.1 %FS Bridge Offset Offset = (OUT+) – (OUT-) %FS -1.25 ±0.5 +1.25 mV/V 0.8 1.0 1.2 mV/V/gauss Field = 0 gauss after Set pulse Sensitivity Set/Reset Current = 0.5A Noise Density @ 1kHz, Vbridge=5V 50 nV/sqrt Hz Resolution 50Hz Bandwidth, Vbridge=5V 120 Pgauss Bandwidth Magnetic signal (lower limit = DC) 5 MHz Disturbing Field Sensitivity starts to degrade. 20 gauss Use S/R pulse to restore sensitivity. Sensitivity TA= -40 to 125°C, Vbridge=5V 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 Tempco Bridge Ohmic Vbridge=5V, TA= -40 to 125°C -3000 2100 -2700 2500 -2400 ppm/°C ppm/°C 2900 ppm/°C Tempco Cross-Axis Effect Max. Exposed Cross field = 1 gauss, Happlied = ±1 gauss ±3 No perming effect on zero reading %FS 10000 gauss 105 % 0.01 degree Field Sensitivity Ratio of TA= -40 to 125°C 95 100 X,Y Sensors (HMC1052 Only) X,Y sensor Sensitive direction in X and Y sensors Orthogonality (HMC1052) * Tested at 25°C except stated otherwise. Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 2 HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS SPECIFICATIONS Characteristics Conditions* Min Typ Max Units Measured from S/R+ to S/R- 3 4.5 6 ohms 0.1% duty cycle, or less, 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 Set/Reset Strap Resistance Current 2Psec current pulse Resistance Tempco Offset Straps Resistance Offset DC Current Constant 10 mA/gauss Field applied in sensitive direction Resistance TA= -40 to 125°C 3500 3900 4300 ppm/°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) HMC1051ZL HMC1051ZL Pinout 8 VB Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 3 7 6 5 4 3 2 1 VO+ OFF+ GND VO- S/R- S/R+ OFF- HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS HMC1052 HMC1052 Pinout Vcc (5) 10 9 8 7 6 HMC1052 B BRIDGE A OUT(10) GND2 GND1 (9) (3) HMC 1052 BRIDGE B OUT+ (4) OUT(7) GND (1) A OUT+ (2) 1 2 3 4 5 Set/Reset Strap S/R+ (6) S/R(8) HMC1052L HMC1052L Pinout HMC1053 HMC1053 Pinout Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 4 HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS PACKAGE OUTLINES PACKAGE DRAWING HMC1051Z (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 PACKAGE DRAWING HMC1051ZL (8-PIN IN-LINE LCC) PACKAGE DRAWING HMC1052 (10-PIN MSOP) Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 5 43 5.9 11.8 122 122 199 HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS PACKAGE DRAWING HMC1052L (16-PIN LCC) Symbol A A1 A3 b D D2 E E2 e L N ND NE r aaa bbb ccc PACKAGE DRAWING HMC1053 (16-PIN LCC) Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 6 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 HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS Basic Device Operation The Honeywell HMC105X family of magnetoresistive sensors are Wheatstone bridge devices to measure magnetic fields. With power supply applied to a bridge, the sensor converts any incident magnetic field in the sensitive axis direction to a differential voltage output. In addition to the bridge circuit, the sensor has two onchip 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 magnetoresistive sensors are made of a nickeliron (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 onedimensional 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. Cross-Axis Effect Cross-Axis effect for the HMR105X series is typically specified at ±3% of full scale to 1 gauss. See application note AN215 regarding this effect and methods for nulling. Offset Strap The offset strap is a spiral of metalization that couples in the sensor element’s sensitive axis. In two-axis designs, the strap is common to both bridges and must be multiplexed if each bridge requires a different strap current. In three-axis designs, the A and B bridges are together with the C bridge sharing a common node for series driving all three bridges’ offset straps. Each 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 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) Autocalibration 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. Noise Characteristics The noise density for the HMR105X series is around 50nV/sqrt Hz at the 1 Hz corner, and quickly drops below 10nV/sqrt Hz at 5Hz and begins to fit the Johnson Noise value at just below 5nV/sqrt Hz beyond 50Hz. The 10Hz noise voltage averages around 1.4 micro-volts with a 0.8 micro-volts standard deviation. The set/reset strap is another spiral of metalization that couples to the sensor elements easy axis (perpendicular to the sensitive axis on the sensor die). Like the offset strap, the set/reset strap runs through a pair of bridge elements to keep the overall die size compact. Each set/reset strap has a nominal resistance of 3 to 6 ohms with a minimum required peak current of 400mA 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 Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 7 HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS accuracy, a single polarity pulse circuit may be employed (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 unipolar application of pulses to the set/reset strap. result would be the magnetic domains aligned in a reverse easy-axis direction so that sensor 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 Iset 5 volts Application Notes Figure 1 Set Pulse Circuit Low Cost 2-Axis Compass Very high precision measurements can be made using the HMC105X family of sensors when interfaced with low noise amplifiers and 12 to 16-bit Analog-to-Digital (A/D) converters. For lower resolution (3° accuracy or more) or low cost compass applications, 8 or 10-bit A/D converters may be used with general purpose operational amplifiers. Figure 2 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 two sensor bridge elements horizontal to the ground (perpendicular to the gravitational field) and to measure the resulting X and Y analog output voltages. With the amplified sensor bridge voltages near-simultaneously converted (measured) to their digital equivalents, the arctangent Y/X can be computed to derive the heading information relative to the X-axis sensitive direction. See the application notes on compassing at Honeywell Magnetic Sensors website (www.magneticsensors.com) for basic principles and detailed application information. U1 1nf Vcc 500k 2.5 to 3.6v 5.00k LMV358 5.00k U3 500k Vref/2 U2 HMC1052 1nf 500k enable 1 MAX1118 data_out clk_in 0 Vref 5.00k LMV358 5.00k 500k Vref/2 set/reset .1uf U4 (2) IRF7509 offset U5 Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 8 set/reset _set/reset Figure 2 Two-Axis Compass HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS Set/Reset Circuit Notes The above set/reset circuit in Figure 1using the IRF7507 dual complementary MOSFETs is shown in detail by Figure 2 in its H-bridge driven configuration. This configuration is used primarily in battery operated applications were the 500mA nominal set/reset pulsed currents can be best obtained under low voltage conditions. Vsr 1Pf 200: S - IRF7509(P) G .1Pf D set/reset D The 200-ohm resistor trickle charges the 1uf supply reservoir capacitor to the Vcc level, and isolates the battery from the high current action of the capacitors and MOSFET switches. Under conventional logic states one totem pole switch holds one node of the 0.1uf capacitor low, while the other switch charges Vcc into the capacitors opposite node. At the first logic change, the capacitor exhibits almost a twice Vcc flip of polarity, giving the series set/reset strap load plenty of pulse current. A restoring logic state flip uses the 0.1uf capacitors stored energy to create a second nearly equal but opposite polarity current pulse through the set/reset strap. G Vsr Rset/reset S IRF7509(P) S 4: IRF7509(N) G D _set/reset D G S Figure 3 H-Bridge Driver IRF7509(N) Vsr 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 4. 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. Vcc + 1Pf 200: Vcc + S - IRF7509(P) G .1Pf D set/reset D G Rset/reset 4: S IRF7509(N) Figure 4 Single-Ended Driver 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 using one, two, or three magnetic sensors. In the example circuit in Figure 5, a HMC1051Z sensor bridge is used with a low voltage capable dual op-amp to detect sufficient intensity of a magnetic field in a single direction. Uses of the circuit include ferrous object detection such as vehicle detection, a “sniffer” for currents in nearby conductors, and magnetic proximity switching. By using two or three sensor circuits with HMC1051, HMC1052, or HMC1053 parts, a more omni-directional sensing pattern can be 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 5k: and the 500k: resistors) matched at 1% tolerance or better to reject commonmode interference signals (EMI, RFI). The ratio of the 500k:/5k: resistors sets the stage gain and can be optimized for a specific purpose. Typical gain ratios for compass and magnetometer circuits using the HMC105X family, range from 50 to 500. The choice of the 5k: 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. Note that Figure 5 also shows an alternative set/reset strap driver circuit using two darlington complentary paired BJTs as electronic switches. Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 9 HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS U1 Vcc .1Pf Vcc 500k 5.0v 5.00k 10k: pot Threshold Set - TLC072 + 5.00k U2 500k output - TLC072 + Vcc/2 LED HMC1051 10k: Vcc * Low ESR Tantalum RLED 200: 1Pf* - + 10k: 0.1Pf FMMT717 .1uf set/reset set/reset FMMT617 S 0.1Pf offset R Figure 5 Magnetic Field Detector 10k: Alternating or Direct Current Sensing The HMC105X family 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 6 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 temperatures. 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 is not critical to this application, but 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. tempco network Rb standoff distance U1 Vcc = 9Vdc .1Pf Rth 500k - 5.00k - RC4558 + + 5.00k Ra RC4458 output U2 500k Figure 6 Current Sensor Vcc/2 ~ +4.5Vdc HMC1051 Vcc =9Vdc * Low ESR Tantalum 200: 1Pf* - + Iac Idc set/reset .1uf set/reset Si1553DL offset Conductor to be Current Measured Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 10 U3 HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS Three Axis Compassing with Tilt Compensation For full three-axis compassing, the circuit depicted in Figure 7 shows both a HMC1051 and a HMC1052 used for sensing the magnetic field in three axes. Alternatively a single HMC1053 could be used for a single sensor package design. A two-axis accelerometer with digital (PWM) outputs is also shown to provide pitch and roll (tilt) sensing, to correct the three-axis magnetic sensors outputs into to the tilt-compensated 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 (per Figure 2) to permit a minimum 1-ampere pulse (500mA per set/reset strap resistance) to both the HMC1052 and HMC1051 sensors. 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 PC 500k Vcc/2 .1uf set/reset with Multiplexed A/D Conv. U4 IRF7509 Vcc offset U5 set/reset Vcc .1Pf 500k Two-axis accelerometer U2 5.00k - LMV324 + 5.00k 500k Vcc/2 HMC1051 Figure 7 Three Axis Compass Solid State Electronics Center • www.magneticsensors.com • (800) 323-8295 • Page 11 xout DI0 yout DI1 HMC1051/HMC1052/HMC1053 SENSOR PRODUCTS 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 HMC105X family of magnetic sensors are very low capacitance (Bandwidth > 5MHz) sensor bridges and can stabilize quickly, typically before the support electronics can. Other energy saving ideas would be to minimize the quantity of set/reset pulses which saves energy over the battery life. Figure 8 shows a simple supply switching circuit that can be microprocessor controlled to duty cycle (toggle) the electronics in moderate current (