A1262 2D, Dual-Channel, Ultrasensitive Hall-Effect Latch FEATURES AND BENEFITS DESCRIPTION • 2D magnetic sensing via planar and vertical Hall elements • Phase separation between the two channels is inherently 90° • 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 □□ Output short-circuit protection □□ Resistant to physical stress □□ Reverse-battery protection □□ Solid-state reliability □□ Superior temperature stability □□ Supply voltage Zener clamp • Small size The A1262 integrated circuit is an ultrasensitive Hall-effect latch. It features operation with traditional planar magnetic field direction as well as vertical. The dual operation of the planar and vertical Hall elements allows the end user to achieve 90° of phase separation that is inherently independent of magnetic pole spacing. The quadrature outputs of the A1262 allow rotation direction to be determined, such as when sensing a rotating ring-magnet target. PACKAGES: The A1262 is available in two 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). The primary option features a vertical Hall plate that is sensitive to magnetic fields parallel with the face of the package across the leaded edges of the package (Y). The -X option features a vertical Hall plate that is sensitive to magnetic fields parallel with the face of the package across the leadless edges of the package (X), resulting in lower total effective air gap. On a single silicon chip, the device includes: two Hall plates (one planar and one vertical), a multiplexer, a small-signal amplifier, chopper stabilization, a Schmitt trigger, and two short-circuit protected NMOS output transistors to sink up to 20 mA. The A1262 features circuitry that provides automotive ruggedness and allows operation from 4 to 24 V over a temperature range 5-Pin SOT23W (Suffix LH) Continued on the next page… 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 GND Functional Block Diagram A1262-DS, Rev. 1 A1262 2D, Dual-Channel, Ultrasensitive Hall-Effect Latch Description (continued) of –40°C to 85°C (E temperature range option) or –40°C to 150°C (K temperature range option). The A1262 is available in a 5-pin SOT23W surface-mount package, magnetically optimized for a variety of orientations. The package is RoHS compliant and lead (Pb) free, with 100% matte-tin leadframe plating. The small geometries of the BiCMOS process allow these devices to be offered in an ultrasmall package suitable for most applications. SPECIFICATIONS Selection Guide Part Number A1262ELHLT-T A1262ELHLX-T A1262LLHLT-T A1262LLHLX-T A1262ELHLT-X-T* A1262ELHLX-X-T* A1262LLHLT-X-T* A1262LLHLX-X-T* Packing 7-in. reel, 3000 pieces/reel 13-in. reel, 10000 pieces/reel 7-in. reel, 3000 pieces/reel 13-in. reel, 10000 pieces/reel 7-in. reel, 3000 pieces/reel 13-in. reel, 10000 pieces/reel 7-in. reel, 3000 pieces/reel 13-in. reel, 10000 pieces/reel Package 5-pin SOT-23W surface mount 5-pin SOT-23W surface mount 5-pin SOT-23W surface mount 5-pin SOT-23W surface mount 5-pin SOT-23W surface mount 5-pin SOT-23W surface mount 5-pin SOT-23W surface mount 5-pin SOT-23W surface mount RoHS COMPLIANT Temperature Range, TA (°C) Description –40 to 85 2 Outputs of Y and Z –40 to 150 –40 to 85 2 Outputs of X and Z –40 to 150 * Contact Allegro regarding availability. Terminal List Table 4 OUTPUTA 2 3 Number GND Symbol 1 VDD 2 OUTPUTA 3 OUTPUTB 4 GND Ground 5 GND Ground GND OUTPUTB Description Connects power supply to chip Output of Z magnetic field direction1 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. 1 Package LH, 5-Pin SOT23W Pinout ΔZ ΔZ Y Δ Y Δ 1 1 Δ X 5 X 1 Δ VDD Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; 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 VOUT 26.5 V Magnetic Flux Density Output Off Voltage Output Sink Current IOUT(Sink) Internally Limited mA Range E –40 to 85 °C Range L Operating Ambient Temperature TA –40 to 150 °C Maximum Junction Temperature2 TJ(MAX) 165 °C Tstg –65 to 170 °C Storage Temperature THERMAL CHARACTERISTICS: May require derating at maximum conditions; see application information Characteristic Symbol Package Thermal Resistance Notes RθJA Package LH-5 4-layer board based on the JEDEC standard Rating Unit 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 er P (R CB, θJ P A= 12 ack 4ºC ag /W e LH ) -5 20 40 60 80 100 120 140 160 180 Temperature (°C) Maximum Power Dissipation versus Ambient Temperature Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 3 A1262 2D, Dual-Channel, Ultrasensitive Hall-Effect Latch ELECTRICAL CHARACTERISTICS: Valid over full operating voltage and ambient temperature ranges, unless otherwise specified. Characteristics Supply Voltage Symbol VDD Output Leakage Current Output On Voltage IOUTOFF VOUT(SAT) Supply Current IDD Reverse-Battery Current IRDD Supply Zener Clamp Voltage 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 – 3 7.5 mA VRDD = –16 V – – –5 mA ICC = 5 mA; TA = 25°C 28 34 – V – – 20 mA – 60 mA Output Sink Current IOUTPUT(SINK) Output Sink Current, Continuous IOUTPUT(SINK)C TJ < TJ(max), VOUT = 12 V 30 Output Sink Current, Peak IOUTPUT(SINK)P t < 3 seconds – – 110 mA – 800 – kHz Chopping Frequency fC Output Rise Time 2,3 tr RL = 820 Ω, CS = 20 pF – 0.2 – µs Output Fall Time 2,3 tf RL = 820 Ω, CS = 20 pF – 0.1 – µs Both channels – 32 48 µs Power-On Time 2 Power-On State 1 2 3 tON POS Low Typical data are at TA = 25°C and VDD = 4 V, and are for initial design estimations only. Power-on time, rise time, and fall time are guaranteed through device characterization. CS = oscilloscope probe capacitance. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 4 A1262 2D, Dual-Channel, Ultrasensitive Hall-Effect Latch MAGNETIC CHARACTERISTICS: Valid over full operating voltage and temperature ranges, unless otherwise specified. Characteristics Operate Point 5 Release Point 5 Hysteresis Symbol Test Conditions BOP BRP BHYS BOP – BRP Min. 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 41 G (gauss) = 0.1 mT (millitesla) 5 Applicable to all directions (X/Y and Z). N S N N S Y X S Z 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. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; 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, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; 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, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; 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, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; 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, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; 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. 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 switchpoint is BOP, or latched off if the last crossed switchpoint 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 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, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; 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 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. 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, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 11 A1262 2D, Dual-Channel, Ultrasensitive Hall-Effect Latch A1262 Sensor and Relationship to Target Power-On Sequence and Timing 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. 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 7: Power-On Sequence and Timing for an illustration of the power-on sequence. The Z-Y option supports the traditional configuration with the face of the package facing the ring magnet (Figure 5a), with the axis of rotation going cross the leads, or with the either of the leaded sides of the package facing the ring magnet (Figure 5b). V 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 VOUT(OFF) Vertical (X/Y) 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 VDD(MIN) Figure 5a Figure 5b 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 6a) lengthwise along the package body, or with either of the non-leaded sides of the package facing the ring magnet (Figure 6b). 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 6a VDD 0 t ON time Figure 7: 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). Figure 6b Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 12 A1262 2D, Dual-Channel, Ultrasensitive Hall-Effect Latch Applications 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 8, a 0.1 µF capacitor is typical. VS VDD CBYP 0.1 µF A1262 RLOAD RLOAD OUTPUTA OUTPUTB Sensor Outputs GND GND Figure 8: Typical Application Circuit Extensive applications information on magnets and Hall-effect sensors is available in: • Hall-Effect IC Applications Guide, AN27701, • Hall-Effect Devices: Guidelines for Designing Subassemblies Using Hall-Effect Devices AN27703.1 • Soldering Methods for Allegro’s Products – SMD and Through-Hole, AN26009 All are provided on the Allegro website: www.allegromicro.com Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 13 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 patented 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 3. 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. The repeatability of magnetic field-induced switching is affected slightly by a chopper technique. However, the Allegro highfrequency chopping approach minimizes the effect of jitter and makes it imperceptible in most applications. Applications that are more likely to be sensitive to such degradation are those requiring precise sensing of alternating magnetic fields—for example, speed sensing of ring-magnet targets. For such applications, Allegro recommends its digital sensor families with lower sensitivity to jitter. For more information on those devices, contact your Allegro sales representative. Multiplexer VDD Low-Pass Filter Sample, Hold & Averaging Amp. Figure 9: Model of Chopper Stabilization Technique Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 14 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) VDD(est) = 16.1 V 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 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, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 15 A1262 2D, Dual-Channel, Ultrasensitive Hall-Effect Latch PACKAGE OUTLINE DRAWING For Reference Only – Not for Tooling Use (Reference DWG-9069) 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 +0.12 2.98 –0.08 +0.020 0.180 –0.053 D 0.11 REF 2.90 4° ±4° A 5 D1 D D1 D +0.10 –0.20 1.91 +0.19 –0.06 D3 D D D2 1 0.17 D REF 2 D2 D 0.25 MIN D D3 0.55 REF D3 D 0.25 BSC Branded Face SEATING PLANE GAUGE PLANE 8X 12° 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 1.00 0.70 0.95 B PCB Reference Layout View C Standard Branding Reference View A Active Area Depth, 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 10: Package LH, 5-Pin SOT23-W Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 16 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 switchpoint symmetry specifications Copyright ©2016, Allegro MicroSystems, LLC Allegro MicroSystems, LLC 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, LLC assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. For the latest version of this document, visit our website: www.allegromicro.com Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 17