A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall-Effect Switches Package LH, 3-pin SOT 3 1. VCC 2. No connection 3. GND NC 1 2 Package UA, 3-pin SIP PTCT 1. VCC 2. GND 3. GND 1 2 3 ABSOLUTE MAXIMUM RATINGS Supply Voltage, VCC .......................................... 28 V Reverse-Supply Voltage, VRCC ........................ –18 V Magnetic Flux Density, B .........................Unlimited Operating Temperature Ambient, TA, Range E.................. –40ºC to 85ºC Ambient, TA, Range L................ –40ºC to 150ºC Maximum Junction, TJ(max)........................165ºC Storage Temperature, TS .................. –65ºC to 170ºC The A1140, A1141, A1142, and A1143 devices are sensitive, two-wire, unipolar, Hall effect switches that are factory-programmed at end-of-line to optimize magnetic switchpoint accuracy. These devices are produced on the Allegro MicroSystems advanced BiCMOS wafer fabrication process, which implements a patented, high-frequency, chopper-stabilization technique that achieves magnetic stability and eliminates the offsets that are inherent in single-element devices exposed to harsh application environments. Commonly found in a number of automotive applications, the A1140-43 family of devices are utilized to sense: seat track position, seat belt buckle presence, hood/trunk latching, and shift selector position. Two-wire unipolar switches are particularly advantageous in price-sensitive applications, because they require one less wire than the more traditional open-collector output switches. Additionally, the system designer gains inherent diagnostics because output current normally flows in either of two narrowly-specified ranges. Any output current level outside of these two ranges is a fault condition. The A1140-43 family of devices also features on-chip transient protection, and a Zener clamp to protect against overvoltage conditions on the supply line. The output currents of the A1141 and A1143 switch HIGH in the presence of a south polarity magnetic field of sufficient strength; and switch LOW otherwise, including when there is no significant magnetic field present. The A1140 and A1142 have inverted output current levels: switching LOW in the presence of a south polarity magnetic field of sufficient strength, and HIGH otherwise. The devices also differ in their specified LOW current supply levels. All family members are offered in two package styles: SOT-23W, a miniature lowprofile package for surface-mount applications (suffix –LH), and TO-92, threelead ultra-mini Single Inline Package (SIP) for through-hole mounting (suffix –UA). Field-programmable versions are also available. Refer to: A1180, A1181, A1182, and A1183. Features and Benefits Chopper stabilization Low switchpoint drift over operating temperature range Low stress sensitivity Factory programmed at end-of-line for optimized switchpoints A1140-DS On-chip protection Supply transient protection Reverse-battery protection On-board voltage regulator 3.5 V to 24 V operation Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches Functional Block Diagram V+ VCC Program/Lock Programming Logic Offset Regulator Clock/Logic Amp Low-Pass Filter Sample and Hold Dynamic Offset Cancellation 0.01 uF GND GND Package UA Only Product Selection Guide Use the complete part numbers when ordering Part Number Package A1140ELH Surface Mount A1140EUA SIP A1140LLH Surface Mount A1140LUA SIP A1141ELH Surface Mount A1141EUA SIP A1141LLH Surface Mount A1141LUA SIP A1142ELH Surface Mount A1142EUA SIP A1142LLH Surface Mount A1142LUA SIP A1143ELH Surface Mount A1143EUA SIP A1143LLH Surface Mount A1143LUA SIP 1South TA (ºC) Output Supply Current at Low Output, ICC(L) (mA) South (+) Field1 Other Field2 2 to 5 Low High 2 to 5 High Low 5 to 6.9 Low High 5 to 6.9 High Low –40 to 85 –40 to 150 –40 to 85 –40 to 150 –40 to 85 –40 to 150 –40 to 85 –40 to 150 (+) magnetic fields must be of sufficient strength. north (–) magnetic fields of sufficient strength, and weak fields of either polarity. 2Includes 2 A1140-DS Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches ELECTRICAL CHARACTERISTICS over the operating voltage and temperature range, unless otherwise specified Characteristic Supply Voltage Supply Current1 Symbol VCC ICC(L) ICC(H) Zener Clamp Supply Voltage VZ(supply) Zener Clamp Supply Current2 IZ(supply) Output Slew Rate3 Chopping Frequency di/dt Test Conditions Min. Typ. Max. Units 3.5 – 24 V B >BOP for A1140; B <BRP for A1141 2 – 5 mA B >BOP for A1142; B <BRP for A1143 5 – 6.9 mA B >BOP for A1141, A1143 B <BRP for A1140, A1142 12 – 17 mA ICC = ICC(max) + 3 mA; TA = 25°C 28 – 40 V VZ(supply) = 28 V – – 10 mA No bypass capacitor; capacitance of the oscilloscope performing the measurement = 20 pF – 36 – mA/µs Device powered on fC Power-On Time4 ton Power-On State5 POS – 400 – kHz After factory programming; with and without bypass capacitor (CBYP = 0.01 µF) – – 25 µs ton ≤ ton(max); VCC slew rate ≥ 25 mV/µs – HIGH – – 1Relative values of B use the algebraic convention, where positive values indicate south magnetic polarity, and negative values indicate north magnetic polarity; therefore greater B values indicate a stronger south polarity field (or a weaker north polarity field, if present). 2The maximum value for I Z(supply) is equal to ICC(L)MAX + 3 mA. 3The value of di is the difference between 90% of I CC(H) and 10% of ICC(L), and the value of dt is time period between those two points. The value of di/dt depends on the value of the bypass capacitor, if one is used, with greater capacitances resulting in lower rates of change. 4The value of t depends on the value of the bypass capacitor, if one is used, with greater capacitances resulting in longer t . on on 5A V slew rate less than 25 mV/µs affects device performance, both while powering-on and while running. For t > t CC on on(max), and BRP < B < BOP, POS is undefined. MAGNETIC CHARACTERISTICS* over the operating voltage and temperature range, unless otherwise specified Characteristic Symbol Operate Point BOP Release Point BRP Hysteresis BHYS Test Conditions ICC(H) → ICC(L) ICC(L) → ICC(H) ICC(L) → ICC(H) ICC(H) → ICC(L) for A1140, A1142 for A1141, A1143 for A1140, A1142 for A1141, A1143 BHYS = BOP – BRP Min. Typ. Max. Units 50 85 115 G 45 – 110 G 5 15 30 G *Relative values of B use the algebraic convention, where positive values indicate south magnetic polarity, and negative values indicate north magnetic polarity; therefore greater B values indicate a stronger south polarity field (or a weaker north polarity field, if present). 3 A1140-DS Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches Characteristic Data 10 ICC(L) versus Ambient Temperature at Various Levels of VCC (A1140, A1141, A1142, A1143) ICC(H) versus Ambient Temperature at Various Levels of VCC (A1140, A1141, A1142, A1143) 20 8 ICC(L) (mA) 6 3.8 V 12.0 V 24.0 V 4 2 0 ICC(H) (mA) 18 VCC VCC 16 3.8 V 12.0 V 24.0 V 14 12 –40 25 10 150 –40 Ambient Temperature, TA (°C) 110 Switchpoint versus Ambient Temperature (A1143) 30 25 150 Ambient Temperature, TA (°C) Hysteresis versus Ambient Temperature (A1143) 105 100 25 95 BHYS (G) BOP (G) 90 85 80 75 20 15 70 10 65 60 55 –50 0 50 100 150 200 5 –50 0 Ambient Temperature, TA (°C) 50 100 150 200 Ambient Temperature, TA (°C) Device Qualification Program Contact Allegro MicroSystems for information. EMC (Electromagnetic Compatibility) Requirements Contact your local representative for EMC results. Test Name Reference Specification ESD – Human Body Model AEC-Q100-002 ESD – Machine Model AEC-Q100-003 Conducted Transients ISO 7637-1 Direct RF Injection ISO 11452-7 Bulk Current Injection ISO 11452-4 TEM Cell ISO 11452-3 4 A1140-DS Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information Characteristic Symbol Test Conditions Package LH, minimum-K PCB (single-sided with copper limited to solder pads) Package LH, low-K PCB (double-sided with 0.926 in2 copper area) Package UA, minimum-K PCB (single-sided with copper limited to solder pads) RθJA Maximum Allowable VCC (V) Package Thermal Resistance Typ. Max Units 110 – – ºC/W 228 – – ºC/W 165 – – ºC/W Power Derating Curve TJ(max) = 165ºC; ICC = ICC(max) 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 VCC(max) Low-K PCB, Package LH (RθJA = 110 ºC/W) Minimum-K PCB, Package UA (RθJA = 165 ºC/W) Minimum-K PCB, Package LH (RθJA = 228 ºC/W) 20 Power Dissipation, PD (m W) Min. 40 60 80 100 120 VCC(min) 140 160 180 Maximum Power Dissipation, PD(max) TJ(max) = 165ºC; VCC = VCC(max); ICC = ICC(max) 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 Lo (R w-K PC θJ A = 11 B, P 0 º ac Min C/ ka W ge (R imum ) LH KP θJA = 165 CB ºC/ , Pac W) kag eU A Min imu m-K (R P θJA = 228 CB, Pa ºC/W ckag e LH ) 20 40 60 80 100 120 Temperature (°C) 140 160 180 5 A1140-DS Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches Functional Description Operation The output, ICC, of the A1140 and A1142 devices switch low after the magnetic field at the Hall sensor exceeds the operate point threshold, BOP. When the magnetic field is reduced to below the release point threshold, BRP, the device output goes high. The differences between the magnetic operate and release point is called the hysteresis of the device, BHYS. This built- I+ in hysteresis allows clean switching of the output even in the presence of external mechanical vibration and electrical noise. The A1141 and A1143 devices switch with opposite polarity for similar BOP and BRP values, in comparison to the A1140 and A1142 (see figure 1). I+ Switch to High ICC ICC ICC(H) Switch to Low Switch to Low Switch to High ICC(H) ICC(L) BRP BHYS (A) A1140, A1142 B+ B– BRP BOP B– ICC(L) 0 BOP 0 B+ BHYS (B) A1141, A1143 Figure 1. Alternative switching behaviors are available in the A114x device family. 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). 6 A1140-DS Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches 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 unique approach used to minimize Hall offset on the chip. The patented Allegro technique, namely dynamic quadrature offset cancellation, removes key sources of the output drift induced by thermal and mechanical stresses. This offset reduction technique is based on a signal modulationdemodulation process. The undesired offset signal is separated from the magnetic field-induced signal in the frequency domain, through modulation. The subsequent demodulation acts as a modulation process for the offset, causing the magnetic fieldinduced signal to recover its original spectrum at baseband, while the dc offset becomes a high-frequency signal. The magneticsourced signal then can pass through a low-pass filter, while the modulated dc offset is suppressed. The chopper stabilization technique uses a 200 kHz high frequency clock. The chopping occurs on each clock edge, result- ing in a 400 kHz chop frequency. 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 integration and sample-and-hold circuits. This process is illustrated in figure 2. The repeatability of magnetic field-induced switching is affected slightly by a chopper technique. However, the Allegro high-frequency chopping approach minimizes the affect 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. Regulator Hall Element Amp Sample and Hold Clock/Logic Low-Pass Filter Figure 2. Chopper stabilization circuit (dynamic quadrature offset cancellation) 7 A1140-DS Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches Application Information For additional general application information, visit the Allegro MicroSystems Web site at www. allegromicro.com. Typical Application Circuit The A114x family of devices must be protected by an external bypass capacitor, CBYP, connected between the supply, VCC, and the ground, GND, of the device. CBYP reduces both external noise and the noise generated by the chopper-stabilization function. As shown in figure 3, a 0.01 µF capacitor is typical. V+ VCC A114x Installation of CBYP must ensure that the traces that connect it to the A114x pins are no greater than 5 mm in length. All high-frequency interferences conducted along the supply lines are passed directly to the load through CBYP, and it serves only to protect the A114x internal circuitry. As a result, the load ECU (electronic control unit) must have sufficient protection, other than CBYP, installed in parallel with the A114x. A series resistor on the supply side, RS (not shown), in combination with CBYP, creates a filter for EMI pulses. (Additional information on EMC is provided on the Allegro MicroSystems Web site.) When determining the minimum VCC requirement of the A114x device, the voltage drops across RS and the ECU sense resistor, RSENSE, must be taken into consideration. The typical value for RSENSE is approximately 100 Ω. B GND CBYP 0.01 uF GND B A A Package UA Only B Maximum separation 5 mm RSENSE ECU Figure 3. Typical application circuit 8 A1140-DS Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches 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 Web site.) 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. PD = VIN × IIN (1) ∆T = PD × RθJA (2) TJ = TA + ∆T (3) Example: Reliability for VCC at TA = 150°C, package UA, using minimum-K PCB. Observe the worst-case ratings for the device, specifically: RθJA = 165°C/W, TJ(max) = 165°C, VCC(max) = 24 V, and ICC(max) = 17 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 ÷ 165 °C/W = 91 mW Finally, invert equation 1 with respect to voltage: VCC(est) = PD(max) ÷ ICC(max) = 91 mW ÷ 17 mA = 5 V The result indicates that, at TA, the application and device can dissipate adequate amounts of heat at voltages ≤VCC(est). Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then reliable operation between VCC(est) and VCC(max) requires enhanced RθJA. If VCC(est) ≥ VCC(max), then operation between VCC(est) and VCC(max) is reliable under these conditions. For example, given common conditions such as: TA= 25°C, VCC = 12 V, ICC = 4 mA, and RθJA = 140 °C/W, then: PD = VCC × ICC = 12 V × 4 mA = 48 mW ∆T = PD × RθJA = 48 mW × 140 °C/W = 7°C TJ = TA + ∆T = 25°C + 7°C = 32°C A worst-case estimate, PD(max), represents the maximum allowable power level (VCC(max), ICC(max)), without exceeding TJ(max), at a selected RθJA and TA. 9 A1140-DS Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches Package LH, 3-Pin; (SOT-23W) 3.10 .122 2.90 .114 1.49 .059 NOM 3 8º 0º 0.28 .011 NOM 0.70 .028 BSC 0.20 .008 0.13 .005 C 0.96 .038 NOM 2.10 .083 1.85 .073 2.40 .094 BSC A 0.25 .010 MIN 3.00 .118 2.70 .106 1.00 .039 BSC 1 2 0.95 .037 BSC 0.25 .010 BSC Seating Plane Gauge Plane 0.50 .020 0.30 .012 1.13 .045 0.87 .034 0.55 .022 REF A Dimensions in millimeters U.S. Customary dimensions (in.) in brackets, for reference only Hall element B Active Area Depth 0.28 [.011] C Fits SC–59A Solder Pad Layout 0.15 .006 0.00 .000 0.95 .037 BSC Package UA, 3-Pin; (TO-92) .164 4.17 .159 4.04 45° BSC .0195 0.50 NOM .0805 2.04 NOM .122 3.10 .117 2.97 .062 1.57 .058 1.47 .0565 1.44 NOM 45° BSC B .085 2.16 MAX .640 16.26 .600 15.24 .031 0.79 REF A 1 2 3 .017 0.44 .014 0.35 .019 0.48 .014 0.36 .050 1.27 BSC Dimensions in inches Metric dimensions (mm) in brackets, for reference only A Dambar removal protrusion B Hall element 10 A1140-DS Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1140/41/42/43 Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches The products described herein are manufactured under one or more of the following U.S. patents: 5,045,920; 5,264,783; 5,442,283; 5,389,889; 5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719; 5,686,894; 5,694,038; 5,729,130; 5,917,320; and other patents pending. Allegro MicroSystems, Inc. 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 products are not authorized for use as critical components in life-support devices or systems without express written approval. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. Copyright © 2004 Allegro MicroSystems, Inc. 11 A1140-DS Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com