A1262ELHLT-T

A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch FEATURES AND BENEFITS DESCRIPTION • 2 D magnetic sensing via planar and vertical Hall elements □□ Quadrature outputs □□ 90° phase separation between channels • Dual-channel output allows independent use of Z-axis planar Hall in conjunction with vertical Hall: □□ Y-axis (default option) □□ X-axis (with -X option) • High sensitivity, BOP typically 17 G • Automotive grade □□ AEC-Q100 qualified for use in automotive applications (L temperature range option) □□ Output short-circuit protection □□ Resistant to physical stress □□ Reverse-battery protection □□ Superior temperature stability □□ Supply voltage Zener clamp • Small size The A1262 is a two channel, latching Hall-effect sensor IC that features both vertical and planar Hall elements. The vertical and planar Hall elements feature sensing axes that are orthogonal to one another and provide 90° of phase separation for ring magnets that is inherently independent of magnet pole spacing and air gap. TYPICAL APPLICATIONS Continued on the next page… • Automotive □□ Blower fans □□ Electric pumps □□ Electronic power steering □□ Seat motors □□ Trunk/liftgate motors □□ Window/sunroof motors • Industrial, Commercial, and Consumer □□ Garage doors □□ Industrial motors □□ Motorized window blinds □□ Motorized gates □□ Pumps □□ White goods The 2D architecture of the A1262 simplifies the design of motors and magnetic encoders by providing quadrature output signals in a very small footprint. The A1262 outputs allow the speed and direction of a rotating ring magnet to be determined. The A1262 is available in two sensing options that allow flexibility in end-system magnetic design. Both options feature a planar Hall plate that is sensitive to magnetic fields perpendicular to the face of the package (Z). Two options of vertical Hall plate orientation (X or Y) in both packages offer flexibility in system design and magnet to sensor placement. PACKAGES: 5-Pin SOT23W (Suffix LH) 4-Pin SIP (Suffix K) Not to scale VDD Regulator To All Subcircuits OUTPUTA Z Hall Low-Pass Filter Amp Sample, Hold & Averaging Demultiplexer X/Y Hall Dynamic Offset Cancellation & Multiplexer Current Limit OUTPUTB Current Limit Functional Block Diagram A1262-DS, Rev. 7 MCO-0000158 GND November 18, 2020 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch DESCRIPTION (continued) On a single silicon chip, the A1262 includes: voltage regulator, reverse battery protection, two Hall plates (one planar and one vertical), a multiplexer, a small-signal amplifier, chopper stabilization, a Schmitt trigger, and two short-circuit protected open-drain outputs that can sink up to 20 mA continuously. (E temperature range option) or –40°C to 150°C (L temperature range option). The A1262 is available in a 5-pin SOT23W surface-mount package (LH) and a 4 pin SIP package (K). Each is offered in two options for a variety of magnet to sensor orientations. The packages are RoHS compliant and lead (Pb) free, with 100% matte-tin leadframe plating. The A1262 is available in two temperature ranges: –40°C to 85°C RoHS COMPLIANT SELECTION GUIDE Part Number Packing Package Temperature Range, TA (°C) A1262ELHLT-T 7-in. reel, 3000 pieces/reel 5-pin SOT-23W surface mount A1262ELHLX-T 13-in. reel, 10000 pieces/reel 5-pin SOT-23W surface mount Description –40 to 85 2 Outputs of Y and Z A1262LK-Y-T Bulk bag, 500 pieces/bag 4-pin SIP through-hole A1262LLHLT-T 7-in. reel, 3000 pieces/reel 5-pin SOT-23W surface mount A1262LLHLX-T 13-in. reel, 10000 pieces/reel 5-pin SOT-23W surface mount A1262ELHLT-X-T 7-in. reel, 3000 pieces/reel 5-pin SOT-23W surface mount A1262ELHLX-X-T 13-in. reel, 10000 pieces/reel 5-pin SOT-23W surface mount A1262LK-X-T Bulk bag, 500 pieces/bag 4-pin SIP through-hole A1262LLHLT-X-T 7-in. reel, 3000 pieces/reel 5-pin SOT-23W surface mount A1262LLHLX-X-T 13-in. reel, 10000 pieces/reel 5-pin SOT-23W surface mount –40 to 150 –40 to 85 2 Outputs of X and Z –40 to 150 Terminal List Table Number 4 GND 3 OUTPUTB VCC 2 OUTPUTA 1 Package K, 4-Pin SIP Pinout 4 GND 3 OUTPUTB VDD 2 2 OUTPUTA 3 3 OUTPUTB 4 4 GND Ground – 5 GND Ground Connects power supply to chip Output of Z magnetic field direction [1] Default option: Output of Y magnetic field direction With -X option: Output of X magnetic field direction Z-axis recommended for use as the speed channel in a speed and direction application, due to better repeatability. ΔZ ΔZ OUTPUTA 2 Δ X Δ X 1 GND 1 1 5 1 Y Δ 1 Description LH Y Δ VDD [1] Symbol K Package LH, 5-Pin SOT23W Pinout Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 2 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch ABSOLUTE MAXIMUM RATINGS Characteristic Symbol Notes Rating Unit 26.5 V Forward Supply Voltage VDD Reverse Supply Voltage VRDD –16 V B Unlimited G Magnetic Flux Density Output Off Voltage Output Sink Current Maximum Junction Temperature VOUT 26.5 V IOUT(SINK) Internally Limited mA 165 °C 175 °C –65 to 170 °C TJ(MAX) Storage Temperature For 500 hours Tstg THERMAL CHARACTERISTICS: May require derating at maximum conditions; see application information Characteristic Symbol Package Thermal Resistance RθJA Notes Rating Unit Package K, single-sided PCB with copper limited to solder pads 177 °C/W Package LH-5 4-layer board based on the JEDEC standard 124 °C/W Power Dissipation, PD (mW) * Additional thermal information available on the Allegro website. 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 4-L ay Sin er P (R CB, θJ P A= 12 ack 4ºC ag /W e LH ) -5 gle -Sid e dP (R C θJA = 177 B, Pa ºC/ W) ckage K 20 40 60 80 100 120 140 160 180 Temperature (°C) Maximum Power Dissipation versus Ambient Temperature Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 3 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch ELECTRICAL CHARACTERISTICS: Valid over full operating voltage and TA = –40°C to 85°C (Range E) or TA = –40°C to 150°C (Range L), unless otherwise specified. Characteristics Symbol Forward Supply Voltage VDD Output Leakage Current IOUTOFF Output On Voltage VOUT(SAT) Supply Current IDD Reverse-Battery Current IRDD Supply Zener Clamp Voltage Output Current VZ Test Conditions Min. Typ. [1] Max. Unit Operating, TJ < 165°C 4 – 24 V B < BRP – – 10 µA IOUT = 20 mA, B > BOP – 180 500 mV 2 3 4.5 mA VRDD = –16 V – – –5 mA ICC = 5 mA; TA = 25°C 28 34 – V – – 20 mA Output Short-Circuit Current Limit IOUT(SINK)LIM IOUT TJ < TJ(max), VOUT = 12 V 30 – 60 mA Output Sink Current, Peak IOUT(SINK)PK t < 3 seconds – – 110 mA – 800 – kHz – µs Chopping Frequency fC Output Rise Time [2][3] tr RL = 820 Ω, CS = 20 pF – 0.2 tf RL = 820 Ω, CS = 20 pF – 0.1 – µs Both channels, VDD > VDD(MIN) – 32 48 µs Output Fall Time [2][3] Power-On Time [2] Power-On State tON POS VDD > VDD(MIN), t< tON Low – Typical data are at TA = 25°C and VDD = 4 V. Power-on time, rise time, and fall time are guaranteed through device characterization. [3] C = oscilloscope probe capacitance. S [1] [2] Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 4 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch MAGNETIC CHARACTERISTICS: Valid over full operating voltage and TA = –40°C to 85°C (Range E) or TA = –40°C to 150°C (Range L), unless otherwise specified. Characteristics Operate Point Symbol [5] BOP Release Point [5] BRP Hysteresis Min. BOP – BRP Typ. Max. Unit [4] 1 17 40 G –40 –17 –1 G 15 34 68 G Symmetry: Channel A, Channel B, BOP(A) + BRP(A), BOP(B) + BRP(B) BSYM(A), BSYM(B) –35 – 35 G Operate Symmetry: BOP(A) – BOP(B) BSYM(AB,OP) –25 – 25 G Release Symmetry: BRP(A) – BRP(B) BSYM(AB,RP) –25 – 25 G [4] 1 BHYS Test Conditions G (gauss) = 0.1 mT (millitesla) to all directions (X/Y and Z). [5] Applicable N N S N N S S X S S N 1 Y Y X S Z Z N The A1262 output is turned on when presented with a south polarity magnetic field beyond BOP in the orientations illustrated above. The X-axis field response is only applicable to the -X option; the Y-axis field response is only applicable to the default option. Note that magnetic polarity between the LH and K X-axis options are opposite. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 5 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch CHARACTERISTIC DATA Average Supply Current vs. Supply Voltage 8 8 7 7 6 4V 5 24 V 4 3 2 1 0 Supply Current, IDD (mA) Supply Current, IDD (mA) Average Supply Current vs. Ambient Temperature -40°C 6 25°C 5 150°C 4 3 2 1 0 -60 -40 -20 0 20 40 60 80 100 120 140 160 2 6 10 Ambient Temperature, TA (°C) VOUT(SAT)-B 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) Output Leakage Current, IOUTOFF (µA) Output On Voltage, VOUT(SAT) (mV) VOUT(SAT)-A -60 -40 -20 Avg. OUTPUTA Operate Point vs. Ambient Temperature 30 25 20 4V 24 V 5 26 0 10 8 IOUT(OFF)-A 6 IOUT(OFF)-B 4 2 0 -60 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) 40 Operate Point, BOP (G) Operate Point, BOP (G) 35 10 22 Avg. OUTPUTA Operate Point vs. Supply Voltage 40 15 18 Avg. Output Leakage Current vs. Ambient Temperature Avg. Output On Voltage vs. Ambient Temperature 500 450 400 350 300 250 200 150 100 50 0 14 Supply Voltage, VDD (V) 35 -40°C 30 25°C 25 150°C 20 15 10 5 0 -60 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) 2 6 10 14 18 22 26 Supply Voltage, VDD (V) Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 6 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch CHARACTERISTIC DATA (continued) Avg. OUTPUTB Operate Point vs. Ambient Temperature Avg. OUTPUTB Operate Point vs. Supply Voltage 40 35 30 25 20 15 4V 10 24 V 5 Operate Point, BOP (G) Operate Point, BOP (G) 40 0 -60 -40 -20 0 20 40 60 80 35 25°C 25 150°C 20 15 10 5 0 100 120 140 160 2 Ambient Temperature, TA (°C) 6 14 18 22 26 Avg. OUTPUTA Release Point vs. Supply Voltage 0 0 -5 -10 -15 -20 -25 4V -30 24 V -35 Release Point, BRP (G) -5 -40 -10 -15 -20 -25 -40°C -30 25°C -35 150°C -40 -60 -40 -20 0 20 40 60 80 100 120 140 160 2 6 Ambient Temperature, TA (°C) 10 14 18 22 26 Supply Voltage, VDD (V) Avg. OUTPUTB Release Point vs. Supply Voltage Avg. OUTPUTB Release Point vs. Ambient Temperature 0 0 -5 -5 -10 -15 -20 -25 4V -30 24 V -35 Release Point, BRP (G) Release Point, BRP (G) 10 Supply Voltage, VDD (V) Avg. OUTPUTA Release Point vs. Ambient Temperature Release Point, BRP (G) -40°C 30 -10 -15 -20 -25 -40°C -30 25°C -35 150°C -40 -40 -60 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) 2 6 10 14 18 22 26 Supply Voltage, VDD (V) Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 7 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch CHARACTERISTIC DATA (continued) Avg. OUTPUTA Hysteresis vs. Ambient Temperature Avg. OUTPUTA Hysteresis vs. Supply Voltage 70 60 4V 50 24 V 40 30 20 10 Hysteresis, BHYS (G) Hysteresis, BHYS (G) 70 -40°C 60 25°C 50 150°C 40 30 20 10 -60 -40 -20 0 20 40 60 80 100 120 140 160 2 6 10 Ambient Temperature, TA (°C) Avg. OUTPUTB Hysteresis vs. Ambient Temperature 40 30 Hysteresis, BHYS (G) Hysteresis, BHYS (G) 24 V 20 10 26 -40°C 60 25°C 50 150°C 40 30 20 10 -60 -40 -20 0 20 40 60 80 100 120 140 160 2 6 10 Ambient Temperature, TA (°C) 14 18 22 26 Supply Voltage, VDD (V) Avg. BOP(A)+BRP(A) Symmetry vs. Ambient Temperature Avg. BOP(B)+BRP(B) Symmetry vs. Ambient Temperature 15 10 4V 5 24 V 0 -5 -10 -15 Symmetry, BSYM(B) (G) 15 Symmetry, BSYM(A) (G) 22 70 4V 50 18 Avg. OUTPUTB Hysteresis vs. Supply Voltage 70 60 14 Supply Voltage, VDD (V) 10 4V 5 24 V 0 -5 -10 -15 -60 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) -60 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 8 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch CHARACTERISTIC DATA (continued) Avg. BOP(A)–BOP(B) Symmetry vs. Ambient Temperature Avg. BRP(A)–BRP(B) Symmetry vs. Ambient Temperature 15 10 4V 5 24 V 0 -5 -10 -15 Symmetry, BSYM(AB,RP) (G) Symmetry, BSYM(AB,OP) (G) 15 10 4V 5 24 V 0 -5 -10 -15 -60 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) -60 -40 -20 0 20 40 60 80 100 120 140 160 Ambient Temperature, TA (°C) Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 9 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch FUNCTIONAL DESCRIPTION Operation V+ This built-in hysteresis allows clean switching of the output even in the presence of external mechanical vibration and electrical noise. The device will power-on in the low output state, even when powering-on in the hysteresis region, between BOP and BRP. Unlike dual-planar Hall-effect sensors, which have two planar Hall-effect sensing elements spaced apart across the width of the package, both the vertical and planar sensing elements on the A1262 are located in essentially the same location on the IC. dual planar Switch to High VOUTPUT B- BRP VOUT(ON) 0 BOP Removal of the magnetic field will leave the device output latched on if the last crossed switch point is BOP, or latched off if the last crossed switch point is BRP. VOUT(OFF) Switch to Low The outputs of the A1262 switch low (turn on) when the corresponding Hall element is presented with a perpendicular south magnetic field of sufficient strength. OUTPUTA switches low if the Z-axis direction exceeds the operate point (BOP), and OUTPUTB switches low if the Y-axis direction (A1262 with default option) or X-axis direction (A1262 with -X option) exceeds BOP. After turn-on, the output voltage is VOUT(SAT). The device outputs switch high (turn off) when the strength of a perpendicular north magnetic field exceeds the release point (BRP). The difference in the magnetic operate and release points is the hysteresis (BHYS) of the device. See Figure 1. B+ BHYS Figure 1: Switching Behavior of Latches On the horizontal axis, the B+ direction indicates increasing south polarity magnetic field strength, and the B– direction indicates decreasing south polarity field strength (including the case of increasing north polarity With dual-planar Hall sensors, the ring magnet must be properly designed and optimized for the physical Hall spacing (distance) in order to have the outputs of the two latches to be in quadrature, or 90 degrees out of phase. With the A1262, which uses one planar and one vertical Hall-effect sensing element, no target optimization is required. When the face of the IC is facing the ring magnet, the planar Hall senses the magnet poles and the vertical Hall senses the transition between poles, therefore the A1262 Dual-Planar Sensor A1262 Figure 2: Ring magnet optimized for a dual-planar Hall-effect sensor resulting in output quadrature also results in quadrature for the A1262. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 10 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch two channels will inherently be in quadrature, irrespective of the ring-magnet pole spacing. Figure 2 above shows a ring magnet optimized for the E1-to-E2 spacing of a dual-planar sensor, resulting in quadrature, or 90 degrees phase separation between channels. This same target also results in quadrature for the 2D sensing A1262. However when a different ring magnet is used which is not optimized for dual planar the E1-to-E2 spacing, the dual-planar sensor exhibits diminished phase separation, making signal processing the outputs into speed and direction less robust. Using a different ring-magnet geometry has no effect on the A1262, and the two channels remain in quadrature (see Figure 3 below). The relationship of the various signals and the typical system timing is shown in Figure 4. A1262 Dual-Planar Sensor A1262 Figure 3: Ring magnet not optimized for a dual-planar Hall-effect sensor resulting in significantly reduced output phase separation, however still results in quadrature for the A1262. Figure 4: Typical System Timing The Planar (P) and Vertical (V) signals represent the magnetic input signal, which is converted to the device outputs, OUTPUTA and OUTPUTB, respectively. While the A1262 does not process the signals into Speed and Direction, these could be determined by the user based on the individual output signals. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 11 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch Output Response to a Speed and Direction Part 2 Clockwise Rotation 1 Bx Bz Counterclockwise Rotation Bz Time (s) Bx Vertical Time (s) Planar 3 Bx A1262 4 Time (s) Figure 5: Typical System Timing The two active Hall signals represent the magnetic input signal, which is converted to the device outputs, OUTPUTA and OUTPUTB. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 12 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch Sampling Cycle Channel A Channel B Channel A Channel B Channel A Channel B Channel A Channel B Channel A Channel B t BOP(A) 0 BRP(A) t BOP(B) 0 BRP(B) t Signal OUTPUTA 0 t Signal OUTPUTB 0 Sampling Cycle Channel B t Channel A Channel B Sampling Cycle Channel A Channel B Channel A Channel B Channel A t t BOP(A) BOP(A) 0 BRP(A) Signal OUTPUTA 0 t t 0 BRP(A) t Signal OUTPUTA 0 Figure 6: Output signal updating with respect to the channel sampling The two active channels are multiplexed with a typical 16 µs sampling period per channel. If the magnetic signal crosses the respective BOP or BRP of a particular channel, that channel’s output will not be updated until the end of its sampling period. If the signal crosses the thresholds while the alternate channel is sampling, the update will occur at the end of the next sampling period (as long as the signal does not cross back over the t thresholds). This is illustrated in Figure 6. The sampling error introduced by the multiplexing increases with magnetic input frequency, which can affect the output duty cycle and phase separation between outputs. Contact your Allegro representative for more information regarding suitability to high frequency applications. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 13 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch A1262 Sensor and Relationship to Target The A1262 is available in two sensing options: with Z-axis planar Hall and the Y-axis vertical Hall active (default option), or with the Z-axis planar Hall and the X-axis vertical Hall active (-X option). This offers incredible flexibility for positioning the IC within various applications. Figure 7a: LH (-Y option) The Z-Y option supports the traditional configuration with the face of the package facing the ring magnet (Figure 7a or 7c), with the axis of rotation going cross the leads, or opposide the leaded side(s) of the package facing the ring magnet (Figure 7b or 7d). Figure 7b: LH (-Y option) Figure 7c: K (-Y option) Figure 7d: K (-Y option) Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 14 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch The Z-X option supports having the IC positioned with the face of the package facing the ring magnet, and the axis of rotation (Figure 8a or 8c) lengthwise along the package body, or with either of the non-leaded sides of the package facing the ring mag- net (Figure 8b or 8d). This latter configuration has the advantage of being able to be mounted extremely close to the ring magnet, since there are no leads or solder pads to accommodate for in that dimension. Figure 8a: LH (-X option) Figure 8b: LH (-X option) Figure 8c: K (-X option) Figure 8d: K (-X option) Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 15 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch Power-On Sequence and Timing Applications The states of OUTPUTA and OUTPUT B are only valid when the supply voltage is within the specified operating range (VDD(MIN) ≤ VDD ≤ VDD(MAX)) and the power-on time has elapsed (t > tON). Refer to Figure 9: Power-On Sequence and Timing for an illustration of the power-on sequence. It is strongly recommended that an external capacitor be connected (in close proximity to the Hall sensor) between the supply and ground of the device to reduce both external noise and noise generated by the chopper stabilization technique. As shown in Figure 10, a 0.1 µF capacitor is typical. V VS VOUT(OFF) Planar (Z) Output Undefined for VDD < VDD(MIN) VOUT(ON) 0 POS V Output Responds According to Magnetic Field Input B > BOP or B < BRP t > tON(MAX) time Output Undefined for VDD < VDD(MIN) VOUT(ON) 0 POS Output Responds According to Magnetic Field Input B > BOP or B < BRP t > tON(MAX) time V RLOAD OUTPUTA OUTPUTB Sensor Outputs GND Figure 10: Typical Application Circuit Extensive applications information on magnets and Hall-effect sensors is available in: VDD(MIN) • Hall-Effect IC Applications Guide, AN27701, VDD 0 CBYP 0.1 µF RLOAD GND VOUT(OFF) Vertical (X/Y) VDD A1262 t ON time Figure 9: Power-On Sequence and Timing Once the supply voltage is within the operational range, the outputs will be in the low state (power-on state), irrespective of the magnetic field. The outputs will remain low until the sensor is fully powered on (t > tON), at which point, both outputs will respond to the corresponding magnetic field presented to the sensor (the vertical Hall channel typically responds before the planar Hall channel). • Hall-Effect Devices: Guidelines for Designing Subassemblies Using Hall-Effect Devices, AN27703.1 • Soldering Methods for Allegro’s Products – SMD and Through-Hole, AN26009 • Air-Gap-Independent Speed and Direction Sensing Using the Allegro A1262, AN296124 • Improved Speed and Direction Sensing Using Vertical Hall Technology, AN296130 All are provided on the Allegro website: www.allegromicro.com Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 16 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch Chopper Stabilization Technique When using Hall-effect technology, a limiting factor for switchpoint accuracy is the small signal voltage developed across the Hall element. This voltage is disproportionally small relative to the offset that can be produced at the output of the Hall sensor. This makes it difficult to process the signal while maintaining an accurate, reliable output over the specified operating temperature and voltage ranges. Chopper stabilization is a proven approach used to minimize Hall offset on the chip. The Allegro technique, namely Dynamic Quadrature Offset Cancellation, removes key sources of output drift induced by thermal and mechanical stresses. This technique is based on a signal modulation-demodulation process. The undesired offset signal is separated from the magnetic fieldinduced signal in the frequency domain, through modulation. The subsequent demodulation acts as a modulation process for the offset, causing the magnetic field induced signal to recover its original spectrum at baseband, while the DC offset becomes a high-frequency signal. The magnetic sourced signal then can pass through a low-pass filter, while the modulated DC offset is suppressed. This configuration is illustrated in Figure 11. The chopper stabilization technique uses a 400 kHz highfrequency clock. For demodulation process, a sample, hold, and averaging technique is used, where the sampling is performed at twice the chopper frequency (800 kHz). This high-frequency operation allows a greater sampling rate, which results in higher accuracy and faster signal-processing capability. This approach desensitizes the chip to the effects of thermal and mechanical stresses, and produces devices that have extremely stable quiescent Hall output voltages and precise recoverability after temperature cycling. This technique is made possible through the use of a BiCMOS process, which allows the use of low-offset, low-noise amplifiers in combination with high-density logic and sample-and-hold circuits. Multiplexer VDD Low-Pass Filter Sample, Hold & Averaging Amp. Figure 11: Model of Chopper Stabilization Technique Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 17 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch POWER DERATING The device must be operated below the maximum junction temperature of the device, TJ(max). Under certain combinations of peak conditions, reliable operation may require derating supplied power or improving the heat dissipation properties of the application. This section presents a procedure for correlating factors affecting operating TJ. (Thermal data is also available on the Allegro MicroSystems website.) The Package Thermal Resistance (RθJA) is a figure of merit summarizing the ability of the application and the device to dissipate heat from the junction (die), through all paths to the ambient air. Its primary component is the Effective Thermal Conductivity (K) of the printed circuit board, including adjacent devices and traces. Radiation from the die through the device case (RθJC) is relatively small component of RθJA. Ambient air temperature (TA) and air motion are significant external factors, damped by overmolding. The effect of varying power levels (Power Dissipation, PD), can be estimated. The following formulas represent the fundamental relationships used to estimate TJ at PD. A worst-case estimate (PD(max)) represents the maximum allowable power level (VDD(max), IDD(max)), without exceeding TJ(max), at a selected RθJA and TA. Example: Reliability for VDD at TA = 150°C, package LH5, using low-K PCB. Observe the worst-case ratings for the device, specifically: RθJA = 124°C/W, TJ(max) = 165°C, VDD(max) = 24 V, and IDD(max) = 7.5 mA. Calculate the maximum allowable power level (PD(max)). First, invert equation 3: ∆Tmax = TJ(max) – TA = 165°C – 150°C = 15°C This provides the allowable increase to TJ resulting from internal power dissipation. Then, invert equation 2: PD(max) = ∆Tmax ÷ RθJA = 15°C ÷ 124°C/W = 121 mW Finally, invert equation 1 with respect to voltage: PD = VIN × IIN (1) VDD(est) = PD(max) ÷ IDD(max) ∆T = PD × RθJA (2) VDD(est) = 121 mW ÷ 7.5 mA TJ = TA + ∆T (3) For example, given common conditions such as: TA = 25°C, VDD = 12 V, IDD = 3 mA, and RθJA = 124°C/W for the LH5 package, then: PD = VDD × IDD = 12 V × 3.0 mA = 36.0 mW ∆T = PD × RθJA = 36.0 mW × 124°C/W = 4.5°C VDD(est) = 16.1 V The result indicates that, at TA, the application and device can dissipate adequate amounts of heat at voltages ≤ VDD(est). Compare VDD(est) to VDD(max). If VDD(est) ≤ VDD(max), then reliable operation between VDD(est) and VDD(max) requires enhanced RθJA. If VDD(est) ≥ VDD(max), then operation between VDD(est) and VDD(max) is reliable under these conditions. TJ = TA + ∆T = 25°C + 4.5°C = 29.5°C Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 18 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch PACKAGE OUTLINE DRAWINGS E +0.08 5.21 –0.05 E1 45° E B E3 E2 2.60 0.11 1.32 +0.08 3.43 –0.05 E E1 E E2 D E 0.17 E2 E E3 1.55 ±0.05 2.16 MAX E E Branded Face E1 E E3 2 3 1 D Standard Branding Reference View 0.84 REF N = Device part number Y = Last two digits of year of manufacture W = Week of manufacture For Reference Only; not for tooling use (reference DWG-9010) Dimensions in millimeters Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown 4 14.73 ±0.51 +0.06 0.38 –0.03 +0.07 0.41 –0.05 YYWW 45° A 1 NNNN Mold Ejector Pin Indent A Dambar removal protrusion (8×) B Gate and tie bar burr area C Branding scale and appearance at supplier discretion D Active Area Depth, 0.42 mm E Hall Elements (E1, E2, and E3), not to scale; E2 and E3 are active in the A1262LK-T; E1 and E3 are active in the A1262LK-X-T 1.27 NOM Figure 12: Package K, 4-Pin SIP Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 19 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch For Reference Only – Not for Tooling Use (Reference DWG-0000628) Dimensions in millimeters – NOT TO SCALE Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown AY +0.12 2.98 –0.08 D 0.11 REF 2.90 4° ±4° AZ AX 5 +0.020 0.180 –0.053 D1 D D1 D +0.10 –0.20 1.91 +0.19 –0.06 D3 D D D2 1 2 0.17 D REF D2 D 0.25 MIN D D3 0.55 REF D3 D 0.25 BSC Branded Face SEATING PLANE GAUGE PLANE 8× 10° ±5° REF 1.00 ±0.13 D D2 +0.10 0.05 –0.05 0.40 ±0.10 0.95 BSC D1 D 0.20 MIN NNN 2.40 C Standard Branding Reference View AX Active Area Distance, X Axis, 1.49 nominally. AX is measured from the edge of the package to the sensitive element; therefore, the tolerances are reflected in the body length dimension. 1.00 0.70 AY Active Area Distance, Y Axis, 0.955 nominally. AY is measured from the edge of the package to the sensitive element; therefore, the tolerances are reflected in the body width dimension. 0.95 B PCB Reference Layout View AZ Active Area Depth, Z Axis, 0.28 ±0.04 B Reference land pattern layout; all pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and PCB layout tolerances C Branding Scale and appearance at supplier discretion D Hall Elements (D1, D2, and D3), not to scale; D2 and D3 are active in the A1262LLH-T; D1 and D3 are active in the A1262LLH-X-T Figure 13: Package LH, 5-Pin SOT23-W Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 20 A1262 2D Dual-Channel Ultrasensitive Hall-Effect Latch Revision History Number Date Description – September 21, 2015 Initial release 1 February 10, 2016 Added E temperature range option and magnetic switch point symmetry specifications 2 February 10, 2017 Updated Features and Benefits (page 1), Description (pages 1-2), Absolute Maximum Ratings table (page 3), Electrical Characteristics table (page 4), Figure 5 (page 12), Figure 6 (page 13), Figure 7 and 8 labels (pages 14-15), Chopper Stabilization section (page 17); added Typical Applications; added K package option; expanded Functional Description section. 3 May 19, 2017 Corrected Pinout Diagrams (page 2). 4 July 31, 2017 Updated Selection Guide table (page 2). 5 August 8, 2018 Minor editorial updates. 6 August 22, 2019 Minor editorial updates. 7 November 18, 2020 Update Package Outline Drawing active area distances (page 20). Copyright 2020, Allegro MicroSystems. Allegro MicroSystems reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. Copies of this document are considered uncontrolled documents. For the latest version of this document, visit our website: www.allegromicro.com Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 21