A3340 Chopper-Stabilized, Precision Hall-Effect Switch Features and Benefits Description ▪ ▪ ▪ ▪ ▪ ▪ ▪ The A3340 Hall effect switch is an extremely temperature-stable and stress-resistant sensor especially suited for operation over extended temperature ranges up to 150°C. Superior high-temperature performance is made possible through dynamic offset cancellation, which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress. Resistant to physical stress Superior temperature stability Output short-circuit protection Operation from unregulated supply Reverse battery protection Solid-state reliability Small size The device includes on a single silicon chip a voltage regulator, Hall-voltage generator, small-signal amplifier, chopper stabilization, Schmitt trigger, and a short-circuit protected open-collector output to sink up to 25 mA. A south pole of sufficient strength will turn the output off. An on-board regulator permits operation with supply voltages of 4.2 to 24 volts. Two package styles provide a magnetically optimized package for most applications. Suffix LH is an SOT23W surface mount package and while suffix UA is a three-lead ultramini SIP for through hole mounting. Packages: 3 pin SOT23W (suffix LH), and 3 pin SIP (suffix UA) The A3340 complements the A3240, which offers the same features, but with the opposite output polarity. Not to scale Functional Block Diagram VCC Regulator Amp Sample and Hold Dynamic Offset Cancellation To All Subcircuits Amp VOUT Control Current Limit <17 GND A3340-DS, Rev. 1 A3340 Chopper-Stabilized, Precision Hall-Effect Switch Selection Guide Part Number Packing* Mounting Ambient, TA A3340ELHLT-T 7-in. reel, 3000 pieces/reel 3-pin SOT23W surface mount A3340EUA-T Bulk, 500 pieces/bag 3-pin SIP through hole A3340LLHLT-T 7-in. reel, 3000 pieces/reel 3-pin SOT23W surface mount A3340LUA-T Bulk, 500 pieces/bag 3-pin SIP through hole BRP (Min) BOP (Max) 5 50 –40ºC to 85ºC –40ºC to 150ºC *Contact Allegro for additional packing options. Absolute Maximum Ratings Rating Units Supply Voltage Characteristic Symbol VCC Notes 26.5 V Reverse Supply Voltage VRCC –30 V Output Off Voltage VOUT 26 V Reverse Output Voltage VROUT –0.5 V 25 mA Internal current limiting (intended to protect the device from output short circuits) Continuous Output Current IOUT Reverse Output Current IROUT –50 mA B Unlimited G Magnetic Flux Density Range E –40 to 85 ºC Range L –40 to 150 ºC Operating Ambient Temperature TA Maximum Junction Temperature TJ(max) 165 ºC Tstg –65 to 170 ºC Storage Temperature Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 2 A3340 Chopper-Stabilized, Precision Hall-Effect Switch Operating Characteristics, valid over TA, unless otherwise noted Characteristic Symbol Test Conditions Min. Typ.1 Max. Units Electrical Characteristics Supply Voltage Range2 VCC Operating, TJ < 165°C 4.2 – 24 V Output Leakage Current IOFF VOUT = 24 V, B > BOP – – 10 μA VOUT(SAT) Output Saturation Voltage IOUT = 20 mA, B < BRP – 185 500 mV Output Current Limit IOM B > BOP 30 – 60 mA Power-On Time tPO VCC > 4.2 V – – 50 μs Chopping Frequency fC – 340 – kHz Output Rise Time tr RLOAD = 820 Ω, CLOAD = 20 pF – 0.2 2.0 μs Output Fall Time tf RLOAD = 820 Ω, CLOAD = 20 pF – 0.1 2.0 μs Supply Current ICC B < BRP, VCC = 12 V – 3.0 6.0 mA B > BOP, VCC = 12 V – 4.0 6.0 mA Reverse Battery Current IRCC VRCC = –30 V – – -5.0 mA Zener Voltage VZD VZ + VD, ICC = 15 mA, TA = 25°C 28 32 37 V Zener Impedance ZZD ZZ + ZD, ICC = 15 mA, TA = 25°C – 50 – Ω Magnetic Characteristics3 Operate Point4 BOP – 35 50 G Point4 BRP 5.0 25 – G – 6 – G Release Hysteresis Bhys BOP – BRP 1Typical data are for initial design estimations only, and assume optimum manufacturing and application conditions, such as TA = 25°C and VCC = 12 V. Performance may vary for individual units, within the specified maximum and minimum limits. 2Maximum voltage must be adjusted for power dissipation and junction temperature. 31 G (gauss) = 0.1 mT (millitesla). 3B OP = operate point (output turns off); BRP = release point (output turns on). Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 3 A3340 Chopper-Stabilized, Precision Hall-Effect Switch THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information Characteristic Symbol Test Conditions RθJA Maximum Allowable VCC (V) Package Thermal Resistance Value Units Package LH, 1-layer PCB with copper limited to solder pads 228 ºC/W Package LH, 2-layer PCB with 0.463 in.2 of copper area each side connected by thermal vias 110 ºC/W Package UA, 1-layer PCB with copper limited to solder pads 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) Package LH, 2-layer PCB (RQJA = 110 ºC/W) Package UA, 1-layer PCB (RQJA = 165 ºC/W) Package LH, 1-layer PCB (RQJA = 228 ºC/W) 20 40 60 80 100 VCC(min) 120 140 160 180 Power Dissipation, PD (mW) Power Dissipation versus Ambient Temperature 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 Pa (R cka ge QJ A = L 11 H, 2 0 º -la Pac C/ ye W (R kage ) r PC UA QJA = B , 165 1-la ºC/ yer W) PC B Pac k (R age LH , QJA = 228 1-laye ºC/W r PC B ) 20 40 60 80 100 120 Temperature (°C) 140 160 180 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 4 A3340 Chopper-Stabilized, Precision Hall-Effect Switch TYPICAL OPERATING CHARACTERISTICS as a function of temperature SWITCH POINTS 50 SWITCH POINTS IN GAUSS 40 OPERATE POINT 30 RELEASE POINT 20 VCC = 4.5 V VCC = 24 V 10 0 -50 -25 0 25 50 75 100 125 AMBIENT TEMPERATURE IN °C 150 Dwg. GH-026-5 OUTPUT SATURATION VOLTAGE SUPPLY CURRENT 300 6.0 IOUT = 20 mA VCC = 12 V 5.0 SUPPLY CURRENT IN mA SATURATION VOLTAGE IN mV VCC = 12 V 200 100 0 -50 -25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE IN ° C 4.0 3.0 2.0 -50 OUTPUT ON, B < BRP OUTPUT OFF, B > BOP -25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE IN ° C Dwg. GH-029-4 Dwg. GH-028-5 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 5 A3340 Chopper-Stabilized, Precision Hall-Effect Switch TYPICAL OPERATING CHARACTERISTICS as a function of supply voltage SWITCH POINTS 40 OPERATE POINT SWITCH POINT IN GAUSS 30 RELEASE POINT TA = 150°C TA = -40°C 20 10 0 3.0 3.5 4.0 4.5 24 5.0 SUPPLY VOLTAGE IN VOLTS Dwg. GH-021-2 OUTPUT SATURATION VOLTAGE SUPPLY CURRENT 250 8.0 OUTPUT ON TA = 150°C TA = +25°C TA = -40°C 7.0 225 6.0 SUPPLY CURRENT IN mA SATURATION VOLTAGE IN mV IOUT = 20 mA TA = 150°C TA = +25°C TA = -40°C 200 175 5.0 4.0 3.0 2.0 1.0 150 3.0 3.5 4.0 4.5 5.0 24 0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 SUPPLY VOLTAGE IN VOLTS SUPPLY VOLTAGE IN VOLTS Dwg. GH-055-1 10 11 12 Dwg. GH-058-4 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 6 A3340 Chopper-Stabilized, Precision Hall-Effect Switch FUNCTIONAL DESCRIPTION More detailed descriptions of the circuit operation can be found in: Technical Paper STP 97-10, Monolithic Magnetic Hall Sensor Using Dynamic Quadrature Offset Cancellation and Technical Paper STP 99-1, Chopper-Stabilized Amplifiers With A Track-andHold Signal Demodulator. Operation. The output of these devices switches high (turns off) when a magnetic field (south pole) perpendicular to the Hall sensor exceeds the operate point threshold (BOP). When the magnetic field is reduced below the release point (BRP), the device output goes low (turns on). After turn-on, the output is capable of sinking 25 mA and the output voltage is VOUT(SAT). The difference in the magnetic operate and release points is the hysteresis (Bhys) of the device. This built-in hysteresis allows clean switching of the output even in the presence of external mechanical vibration and electrical noise. Applications. It is strongly recommended that an external bypass 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 chopperstabilization technique. X B +V C C Dwg. EH-012 +VHALL –V HALL +V VCC OUT P UT V OL T A G E Chopper-Stabilized Technique. The Hall element can be considered as a resistor array similar to a Wheatstone bridge. A large portion of the offset is a result of the mismatching of these resistors. These devices use a proprietary dynamic offset cancellation technique, with an internal high-frequency clock to reduce the residual offset voltage of the Hall element that is normally caused by device overmolding, temperature dependencies, and thermal stress. The chopper-stabilizing technique cancels the mismatching of the resistor circuit by changing the direction of the current flowing through the Hall plate using CMOS switches and Hall voltage measurement taps, while maintaing the Hallvoltage signal that is induced by the external magnetic flux. The signal is then captured by a sample-andhold circuit and further processed using low-offset bipolar circuitry. This technique produces devices that have an extremely stable quiescent Hall output voltage, are immune to thermal stress, and have precise recoverability after temperature cycling. This technique will also slightly degrade the device output repeatability. A relatively high sampling frequency is used in order that faster signals can be processed. SAMPLE & HOLD REG B RP B OP V OUT (S AT ) 0 0 +B F L UX DE NS IT Y SUPPLY The simplest form of magnet that will operate these devices is a ring magnet. Other methods of operation, such as linear magnets, are possible. Extensive applications information on magnets and Hall-effect sensors is also available in Application Note 27701, or at www.allegromicro.com. OUTPUT PTCT VOUT GND X 0.1 μF VCC SUPPLY Dwg. EH-013 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 7 A3340 Chopper-Stabilized, Precision Hall-Effect Switch Package LH, 3-Pin (SOT-23W) 2.975 1.49 B A 3 4º 0.28 0.180 0.96 B 2.90 1.91 B 0.38 2 1 0.25 Seating Plane Gauge Plane 10º 1.00 10º 0.95 0.40 All dimensions nominal, not for tooling use Dimensions in millimeters 0.05 A Active Area Depth B Hall element, not to scale Pin-out Diagrams Package UA G Package LH 3 X X PTCT PTCT 1 2 1 2 3 Terminal List Name VCC VOUT GND Description Connects power supply to chip Output from circuit Ground Number Package LH Package UA 1 1 2 3 3 2 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 8 A3340 Chopper-Stabilized, Precision Hall-Effect Switch Package UA, 3-Pin SIP .161 [4.09] 45° A .0195 [0.50] B .081 2.06 .060 [1.52] B .057 1.45 .119 [3.02] 45° B .085 [2.16] MAX .031 [0.79] .016 [0.41] .590 [14.99] 1 .017 [0.43] .050 [1.27] 2 3 All dimensions nominal, not for tooling use Dimensions in inches, metric dimensions (mm) in brackets, for reference only A Active Area Depth B Hall element (not to scale) Copyright ©2004, 2007, Allegro MicroSystems, Inc. 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’s products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system. 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. For the latest version of this document, visit our website: www.allegromicro.com Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 9