AAT001-10E

AAT00x Angle Sensors AAT00x Ultralow Power TMR Angle Sensors Features Tunneling Magnetoresistance (TMR) technology Sub-microwatt power consumption High output signal without amplification Immune to airgap variations Operates with as little as 30 Oersted field Sine and cosine and outputs −40°C to +125°C operating temperature Ultraminiature TDFN6 packages • • • • • • • • Applications • Battery-powered applications • Knob position sensors • Rotary encoders • Automotive rotary position sensors • Motor shaft position sensors Description AAT00x angle sensors use unique Tunneling Magnetoresistance (TMR) elements for large signals and low power consumption. Functional Diagram The sensors provide sine and cosine signals defining the angle of rotation. Outputs are proportional to the supply voltage and peak-to-peak output voltages are much larger than conventional sensor technologies. Vcc Vcc Rota tio n Cos GND Sin AAT00x sensors consist of two half-bridges. The AAT001 has a typical bridge resistance of 1.25 MΩ for ultra-low power, and the AAT009 has a bridge resistance of 6 MΩ for ultra-ultra-low power. GND Parts are packaged in NVE’s 2.5 mm x 2.5 mm x 0.8 mm TDFN6 surface-mount package. 1 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors Absolute Maximum Ratings Parameter Supply voltage Reverse supply voltage Storage temperature ESD (Human Body Model) Applied magnetic field Min. −40 Max. 7 −12 170 2000 Unlimited1 Units Volts Volts °C Volts Oe Operating Specifications Parameter Operating temperature Device resistance AAT001 AAT009 Peak-to-peak output signal Offset voltage Supply voltage Required applied magnetic field Repeatability, fixed bias2 Repeatability, variable bias3 Symbol Tmin; Tmax VPP-SIN VPP-COS VOFFSET-SIN VOFFSET-COS VCC Min. −40 Typ. Max. 125 Units °C 0.6 4 1.25 6 2.5 10 MΩ MΩ 130 200 mV/V −10 +10 mV/V 0 30 5.5 200 ±0.5 ±3 Test Condition 25°C with required magnetic field. Over full rotation. Temperature coefficient of resistance TCOR +0.09 V Oe deg. deg. % of peak-to-peak output; 50 Oe applied field; 25°C %/°C Output voltage temperature coefficient TCOV −0.13 %/°C Nonsinusoidality4 Notes: 1. 2. 3. 4. ±1.5% Constant supply voltage. Large magnetic fields CANNOT damage NVE sensors. “Fixed Bias” means a fixed airgap between the bias magnet and sensor so the magnetic field at the sensor is constant. “Variable Bias” means the magnetic field strength at the sensor can vary across the specification range. Maximum deviation of either output from an ideal sine wave. 2 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors Operation Overview—Unique TMR technology The heart of the unique sensor is an array of four Tunneling Magnetoresistance (TMR) elements in each quadrant. TMR technology enables low power and miniaturization, making the sensors ideal for battery operation. In a typical configuration, an external magnet provides a saturating magnetic field in the plane of the sensor, as illustrated below for a bar magnet and a radially-magnetized disk magnet: Figure 1. Sensor operation. The device contains four sensing resistors at 90 degree intervals. The resistors are connected as two half-bridges, providing the sine and cosine voltage outputs. For each half bridge, the resistance of one element increases and the other decreases as the field rotates. Thus the bridge resistance, device resistance, and output impedances remain constant with rotation. Transfer function The half-bridge configuration provides a simple interface and can simplify external circuitry such as amplifiers and comparators. Outputs are sinusoidal, centered around half the supply, and ratiometric with supply voltage. Mathematically, the outputs can be expressed as: VSIN = [VCC-SIN][(VSIN-MAX – VSIN-MIN) / 2)Sin θ + VCC-SIN / 2 + VOFFSET-SIN] VCOS = [VCC-COS][(VCOS-MAX – VCOS-MIN) / 2)Cos θ + VCC-COS / 2 + VOFFSET-COS] Where: θ is the magnetic field angle; VCOS and VSIN are the sensor output voltages (mV/V); VCC-SIN and VCC-COS are the sensor supply voltages (normally tied together); VSIN-MAX, VCOS-MAX, VSIN-MIN, and VCOS-MIN are the sensor output peak signal levels (mV/V); and VOFFSET-SIN and VOFFSET-COS are the sensor offset voltages (mV/V), defined as the average of the maximum and minimum outputs minus half the supply voltage. Wide range of magnets and magnet locations The sensors operate with fields from 30 Oe to 200 Oe. This wide magnetic field range allows inexpensive magnets and operation over a wide range of magnet spacing. Larger or stronger magnets require more distance to avoid oversaturating the sensor; smaller or weaker magnets may require closer spacing. Low-cost radially-magnetized ferrite disk magnets can be used with these sensors in production. Bar magnets are also used in some configurations. 3 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors Ideal for battery and harvested power AAT-Series sensors are resistive devices with no active components, so they have no minimum voltage and can be powered from single cells. With their low power, the sensors are well-suited for operation from batteries or harvested power. The AAT009 is especially ideal for such applications because of its extremely high bridge resistance. AAT009 sensors can run continuously for many years on small alkaline, silver oxide, or lithium button cells. Harvested power is often intermittent, and AAT-Series sensors detect and maintain absolute position information. The sensors immediately powers up indicating the correct position after power is restored. The following chart shows a typical sensor output versus the angle of applied field at different air gaps: 2.9 Cosine, 3mm 2.8 Sine, 3mm Cosine, 4mm 2.7 Sine, 4mm Cosine, 5mm Voltage 2.6 Sine, 5mm 2.5 2.4 2.3 2.2 2.1 2 0 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 Degrees of Rotation Figure 2. AAT001 Typical Output with Variations in Airgap (5V supply; 12 mm diameter, 4 mm thick split-pole ferrite magnet; 5 V supply). One cycle per revolution Other sensor types such as AMR have two cycles per revolution, so they cannot determine absolute position for 360-degree rotation. AAT-Series sensors output one cycle per revolution and can unambiguously determine position within a full rotation. Detects absolute position Unlike some encoder types, AAT-Series sensors detect absolute position, and maintain position information when power is removed. The sensor immediately powers up indicating the correct position. 4 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors Application Circuitry External comparators A dual comparator can provide digital outputs from AAT angle sensors. Low-power comparators and large resistors are used to avoid adding power consumption to low-power applications: 3.3 V AAT00x Sensor 1 Vcc 6 Vcc R3 (Cosine) + 5M 100 nF R2 (Sine) - R1 (Sine) 5M GND 3 MCP 6542 0 + GND 4 R4 (Cosine) Sgn(Cos) Sgn(Sin) - 5 Sin 2 Cos 90˚ 180˚ 270˚ Rotation 360˚ Figure 2. External dual comparator for digital outputs. Inherent comparator hysteresis eliminates noise at the transition points. The MCP6542 comparator hysteresis of 3.3 mV corresponds to about 1 angular degree of hysteresis. Higher hysteresis comparators can be used for more noise immunity at the expense of hysteresis. NVE also offers ADT-Series sensors that include integrated comparators to replicate the circuit of Figure 2. Quadrant outputs A 2-to-4 line decoder can provide digital signals to indicate the quadrant of rotation: 3.3 V AAT00x Sensor 1 Vcc 100 nF R3 (Cosine) 6 Vcc 5M R2 (Sine) 5 Sin 2 Cos + R1 (Sine) GND 3 R4 (Cosine) 750 A Y3 Y2 Y1 B Y0 GND 4 5M MCP 6542 + 0˚-90˚ 270˚-360˚ 90˚-180˚ 180˚-270˚ SN74LV C1G139 Figure 3. Digital Quadrant Outputs. 5 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors Speed and direction signals Commodity CMOS circuits can be added to create a precise encoder with direction and speed outputs. A flip-flop determines direction by detecting the phasing between the two outputs. An exclusive-OR gate provides a digital signal with two cycles per revolution, and transitions every 90 degrees: 3.3 V AAT00x Sensor 1 Vcc 100 nF 6 Vcc R3 (Cosine) 5M R2 (Sine) - R1 (Sine) 5M GND 3 R4 (Cosine) 7SZ86 Speed (2/rev) - 5 Sin 2 Cos + GND 4 TLV 3502 0 90˚ 180˚ 270˚ 360˚ D + Q Direction CLK SN74 AUP1G79 Figure 4. Speed and direction signals. Rotation reference signals An AAT angle sensor and a single comparator can provide a precise angular reference point and a one cycle-per-rotation signal. Comparing the sine and cosine outputs is more precise than comparing either to a reference because it corrects for temperature. 0.9 to 5.5 V AAT00x Sensor 1 Vcc 100 nF R3 (Cosine) 6 Vcc R2 (Sine) Sin Cos 5 Sin 2 Cos R1 (Sine) GND 3 R4 (Cosine) OUT GND 4 0 45˚ + OUT - TLV3691 225˚ 360˚ Figure 5. Angular Reference Point Rotation Signal. In this circuit, the output is high from nominal 45 to 225 degrees, and low from 225 to 45 degrees. A low voltage, low quiescent current comparator is used to preserve the AAT sensors’ ultra-low power and wide supply range. Inherent comparator hysteresis eliminates noise at the transition points. The TLV3691 comparator hysteresis of 17 mV corresponds to approximately 6 degrees of hysteresis with a 1.5 V supply. A TS881 or similar comparator has a typical hysteresis of 4 mV, corresponding to 1.5 angular degrees of hysteresis. 6 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors Low-power amplification AAT-Series sensors have high output signals without amplification, but if amplification is required, a circuit like the one below can be used. The 10 megohm resistors and nanopower TLV522 op-amp minimize the added power consumption of the amplifier. A gain of three amplifies the sensor’s typical peak-to-peak signal level of 200 mV/V to 60% of rail-to-rail (one volt/volt), providing more usable signal without risk of saturating the amplifier for a sensor at the high end of the output signal range: 1.7 V to 5.5 V AAT00x Sensor 1 Vcc 100 nF 10M 6 Vcc R3 (Cosine) - R2 (Sine) R1 (Sine) + TLV522 10M 10M GND 4 R4 (Cosine) 3Sin 10M 5 Sin 2 Cos GND 3 10M 10M 3Cos + 2x 10 pF Figure 6. 3x Preamplifier. Although AAT00x sensors are designed to be used primarily as two half bridges, if quadrature outputs are not required, a similar differential amplifier circuit can provide a larger signal, more precision, and less temperature dependence than either the sine or cosine output alone: 5V AAT00x Sensor 1 Vcc 100 nF R3 (Cosine) 6 Vcc R2 (Sine) 5 Sin 2 Cos Sin-Cos 45˚ R1 (Sine) GND 3 R4 (Cosine) 225˚ 2x 1K GND 4 + RG=33K (Gain = 2.5) (Vp-p) REF 2x 100 pF INA826 Figure 7. 2.5x Differential Amplifier. The differential (VSIN − VCOS) voltage has an amplitude of 1.41 times the amplitude of either output, or typically 282 mV/V peak-topeak. Therefore the amplifier gain of 2.5 provides a typical peak-to-peak output of 71% of rail-to-rail (one volt/volt). Note that the zero crossing is at 45 degrees, versus to 0 degrees for the Sin output and 90 degrees for the Cos output. An instrumentation amplifier can be used to minimize parts count when power consumption is not critical. 7 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors Noise mitigation High-impedance circuitry is inherently susceptible to noise. Common noise mitigation steps include: • Power supply decoupling capacitors near the sensor (100 nF typical). • Limiting the sensor output bandwidth to only what is needed. Because the sensor outputs are resistive, filter capacitors can be connected directly to the outputs. The sensor output impedances are half the bridge resistance, so the cutoff frequency is: fc = 1/(π RB C) where RB is the bridge resistance and C is the output capacitance. • Digital filtering or averaging in microcontroller systems. External comparator considerations Low voltage, low quiescent current comparators are generally used to preserve the AAT sensors’ ultra-low power and wide supply range. Some hysteresis in external comparators is desirable to reduce noise and jitter at transition points. Too much hysteresis, however, may cause undesirable errors. Low-hysteresis comparators are especially important in low voltage applications, since hysteresis is a larger portion of the signals. Angular hysteresis relates to comparator hysteresis as follows: θH = (360/π)(VHC) (VCC)(VPP) Where: θH the angular hysteresis in degrees; VHC is the comparator’s hysteresis; VCC is the sensor power supply; and VPP is the sensor’s peak-to-peak sensitivity (typically 200 mV/V). For example, MCP6542 comparators have hysteresis of 3.3 mV, corresponding to about 1 angular degree of hysteresis. TLV3691 or similar comparators have hysteresis of 17 mV, corresponding to approximately 6 degrees of hysteresis with a 1.5 V supply. Ultralow power external CMOS Any of the application circuits described in this section can use 74AUP-family logic rather than 74LVC if lower power is required and five-volt operation is not needed. 8 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors Pinout 1 Vcc 6 Vcc Rota tio n 0˚ 5 Sin 2 Cos 3 GND 4 GND AAT00x Pin 1 2 3 4 5 6 Symbol VCC-COS Cos GND GND Sin VCC-SIN Description Supply voltage (up to 5.5 V) for the Cos sensor elements. Corresponds to the cosine of the rotation angle. Ground for the Cos sensor elements. Ground for the Sin sensor elements. Corresponds to the sine of the rotation angle. Supply voltage for the Sin sensor elements. Notes: • Clockwise rotation as viewed from the top of the package is interpreted as increasing angle. • The package center pad may be left floating or connected to ground. • This product has been tested for electrostatic sensitivity to the limits stated in the specifications. However, NVE recommends that all integrated circuits be handled with appropriate care to avoid damage. Damage caused by inappropriate handling or storage could range from performance degradation to complete failure. Available Parts Part Number AAT001-10E AAT009-10E Typ. Bridge Resistance 1.25 MΩ 6 MΩ Marking FCVe FDZe 9 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors 2.5 mm x 2.5 mm TDFN6 Package 2.00 ± 0.05 0.80 MAX. 6 4 6 2.50±0.10 1.30±0.05 4 C0.10 PIN 1 ID 1 1 3 3 0.30±0.05 (6X) 2.50 ± 0.10 0.0-0.05 0.30±0.05 0.65 TYP. (4X) 1.30 REF (2X) 0.20 REF RoHS Notes: • Dimensions in millimeters. • Soldering profile per JEDEC J-STD-020C, MSL 1. COMPLIANT 10 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors Revision History April 2017 Changes • Clarified repeatability vs. accuracy (p. 2). • Added nonsinusoidality specification (p. 2). • Lower-power amplifier circuit (p. 7). November 2016 Changes • Split out AAT003 into a separate datasheet. • Revised applications section. June 2016 Changes • Consolidated AAT001, AAT003, and AAT009 datasheets. • Added application circuits. • Added microcontroller interface application section. 11 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors Datasheet Limitations The information and data provided in datasheets shall define the specification of the product as agreed between NVE and its customer, unless NVE and customer have explicitly agreed otherwise in writing. All specifications are based on NVE test protocols. In no event however, shall an agreement be valid in which the NVE product is deemed to offer functions and qualities beyond those described in the datasheet. Limited Warranty and Liability Information in this document is believed to be accurate and reliable. However, NVE does not give any representations or warranties, expressed or implied, as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information. In no event shall NVE be liable for any indirect, incidental, punitive, special or consequential damages (including, without limitation, lost profits, lost savings, business interruption, costs related to the removal or replacement of any products or rework charges) whether or not such damages are based on tort (including negligence), warranty, breach of contract or any other legal theory. Right to Make Changes NVE reserves the right to make changes to information published in this document including, without limitation, specifications and product descriptions at any time and without notice. This document supersedes and replaces all information supplied prior to its publication. Use in Life-Critical or Safety-Critical Applications Unless NVE and a customer explicitly agree otherwise in writing, NVE products are not designed, authorized or warranted to be suitable for use in life support, life-critical or safety-critical devices or equipment. NVE accepts no liability for inclusion or use of NVE products in such applications and such inclusion or use is at the customer’s own risk. Should the customer use NVE products for such application whether authorized by NVE or not, the customer shall indemnify and hold NVE harmless against all claims and damages. Applications Applications described in this datasheet are illustrative only. NVE makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification. Customers are responsible for the design and operation of their applications and products using NVE products, and NVE accepts no liability for any assistance with applications or customer product design. It is customer’s sole responsibility to determine whether the NVE product is suitable and fit for the customer’s applications and products planned, as well as for the planned application and use of customer’s third party customers. Customers should provide appropriate design and operating safeguards to minimize the risks associated with their applications and products. NVE does not accept any liability related to any default, damage, costs or problem which is based on any weakness or default in the customer’s applications or products, or the application or use by customer’s third party customers. The customer is responsible for all necessary testing for the customer’s applications and products using NVE products in order to avoid a default of the applications and the products or of the application or use by customer’s third party customers. NVE accepts no liability in this respect. Limiting Values Stress above one or more limiting values (as defined in the Absolute Maximum Ratings System of IEC 60134) will cause permanent damage to the device. Limiting values are stress ratings only and operation of the device at these or any other conditions above those given in the recommended operating conditions of the datasheet is not warranted. Constant or repeated exposure to limiting values will permanently and irreversibly affect the quality and reliability of the device. Terms and Conditions of Sale In case an individual agreement is concluded only the terms and conditions of the respective agreement shall apply. NVE hereby expressly objects to applying the customer’s general terms and conditions with regard to the purchase of NVE products by customer. No Offer to Sell or License Nothing in this document may be interpreted or construed as an offer to sell products that is open for acceptance or the grant, conveyance or implication of any license under any copyrights, patents or other industrial or intellectual property rights. Export Control This document as well as the items described herein may be subject to export control regulations. Export might require a prior authorization from national authorities. Automotive Qualified Products Unless the datasheet expressly states that a specific NVE product is automotive qualified, the product is not suitable for automotive use. It is neither qualified nor tested in accordance with automotive testing or application requirements. NVE accepts no liability for inclusion or use of non-automotive qualified products in automotive equipment or applications. In the event that customer uses the product for design-in and use in automotive applications to automotive specifications and standards, customer (a) shall use the product without NVE’s warranty of the product for such automotive applications, use and specifications, and (b) whenever customer uses the product for automotive applications beyond NVE’s specifications such use shall be solely at customer’s own risk, and (c) customer fully indemnifies NVE for any liability, damages or failed product claims resulting from customer design and use of the product for automotive applications beyond NVE’s standard warranty and NVE’s product specifications. 12 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation AAT00x Angle Sensors An ISO 9001 Certified Company NVE Corporation 11409 Valley View Road Eden Prairie, MN 55344-3617 USA Telephone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com e-mail: sensor-info@nve.com ©NVE Corporation All rights are reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. SB-00-024_AAT00x-10E April 2017 13 NVE Corporation 11409 Valley View Road, Eden Prairie, MN 55344-3617 Phone: (952) 829-9217 Fax: (952) 829-9189 www.nve.com ©NVE Corporation