A3240 Chopper-Stabilized, Precision Hall-Effect Switch Not for New Design These parts are in production but have been determined to be NOT FOR NEW DESIGN. This classification indicates that sale of this device is currently restricted to existing customer applications. The device should not be purchased for new design applications because obsolescence in the near future is probable. Samples are no longer available. Date of status change: May 4, 2009 Recommended Substitutions: The replacement part is the A1120 next-generation chopper-stabilized switch. NOTE: For detailed information on purchasing options, contact your local Allegro field applications engineer or sales representative. Allegro MicroSystems, Inc. reserves the right to make, from time to time, revisions to the anticipated product life cycle plan for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use. A3240 Chopper-Stabilized, Precision Hall-Effect Switch Features and Benefits Description ▪ Resistant to Physical Stress ▪ Superior Temperature Stability ▪ Output Short-Circuit Protection ▪ Operation From Unregulated Supply ▪ Reverse Battery Protection ▪ Solid-State Reliability ▪ Small Size The A3240 Hall-effect switch is an extremely temperature-stable and stress-resistant sensor especially suited for operation over extended temperature ranges 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. 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 on. An on-board regulator permits operation with supply voltages of 4.2 to 24 volts. Packages: 3-pin SOT89 (LT package) 3-pin SOT23W (LH package) 3-pin SIP (UA package) Not to scale Three package styles provide a magnetically optimized package for most applications. Package type LH is a modified SOT23W surface-mount package, LT is a miniature SOT89/TO-243AA transistor package for surface-mount applications; while UA is a three-lead ultra-mini-SIP for through-hole mounting. The LH and UA packages are also available in a lead (Pb) free version (suffix, –T) , with a 100% matte tin plated leadframe. Functional Block Diagram SUPPLY TO ALL SUBCIRCUITS LOW-PASS FILTER OUTPUT SAMPLE & HOLD X DYNAMIC OFFSET CANCELLATION REG. CONTROL CURRENT LIMIT <17 GROUND Dwg. FH-020-1 27621.20h A3240 Chopper-Stabilized, Precision Hall-Effect Switch Selection Guide Part Number Packing* Mounting A3240ELHLT-T 7-in. reel, 3000 pieces/reel Surface Mount A3240ELTTR-T 7-in. reel, 1000 pieces/reel Surface Mount A3240EUA-T Bulk, 500 pieces/bag A3240LLHLT-T 7-in. reel, 3000 pieces/reel Surface Mount 7-in. reel, 1000 pieces/reel Surface Mount A3240LUA-T Bulk, 500 pieces/bag BRP(MIN) (G) BOP(MAX) (G) 5.0 50 –40 to 85 SIP through hole A3240LLTTR-T *Contact Ambient, TA (ºC) –40 to 150 SIP through hole Allegro for additional packing options. Absolute Maximum Ratings Rating Unit Supply Voltage Characteristic Symbol VCC Notes 26.5 V Reverse Battery Voltage VRCC –30 V Output Off Voltage VOUT 26 V Continuous Output Current IOUT 25 mA Reverse Output Current IROUT –50 mA See graph W Unlimited G Internal current limiting is intended to protect the device from output short circuits. Package Power Dissipation PD Magnetic Flux Density B 1 G = 0.1 mT (millitesla) Operating Ambient Temperature TA Range E –40 to 85 ºC Range L –40 to 150 ºC TJ(max) 165 ºC Tstg –65 to 170 ºC Maximum Junction Temperature Storage Temperature Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 2 A3240 Chopper-Stabilized, Precision Hall-Effect Switch Suffix ‘–LT’ & ‘–UA’ Pinning Suffix ‘–LH’ Pinning (SOT89/TO-243AA & ultra-min SIP) (SOT23W) 3 X PTCT V PTCT CC V CC 2 3 SUPPLY GROUND OUTPUT 1 1 2 Dwg. PH-003-4 Dwg. PH-003-2 Pinning is shown viewed from branded side. Package Power Dissipation 800 700 Suffix "–UA" R θJA = 165°C/W 600 500 Suffix "–LT" R θJA = 180°C/W Suffix "–LH" R θJA = 228°C/W 400 300 200 Suffix "E–" 100 Suffix "L–" 0 20 40 60 80 120 100 AMBIENT TEMPERATURE in °C 140 160 180 Dwg. GH-046-2D Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com Copyright © 2000, 2003 Allegro MicroSystems, Inc. 3 A3240 Chopper-Stabilized, Precision Hall-Effect Switch ELECTRICAL CHARACTERISTICS over operating temperature range. Limits Characteristic Symbol Test Conditions Min. Typ. Max. Units 4.2 – 24 V Supply Voltage Range VCC Operating, TJ < 170°C1 Output Leakage Current IOFF VOUT = 24 V, B < BRP – – 10 μA VOUT(SAT) IOUT = 20 mA, B > BOP – 185 500 mV Output Saturation Voltage 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 RL = 820 , CL = 20 pF – 0.2 2.0 μs Output Fall Time tf RL = 820 , CL = 20 pF – 0.1 2.0 μs B < BRP, VCC = 12 V – 3.0 6.0 mA B > BOP, VCC = 12 V – 4.0 6.0 mA VRCC = -30 V – – -5.0 mA Supply Current Reverse Battery Current ICC ICC Zener Voltage VZ + VD ICC = 15 mA, TA = 25°C 28 32 37 V Zener Impedance zz + zD ICC = 15 mA, TA = 25°C – 50 – NOTES: 1. Maximum voltage must be adjusted for power dissipation and junction temperature. 2. BOP = operate point (output turns on); BRP = release point (output turns off). 3. Typical Data is at TA = +25°C and VCC = 12 V and is for design information only. MAGNETIC CHARACTERISTICS over operating supply voltage and temperature ranges. Test Conditions Symbol Operate Point BOP – 35 50 G Release Point BRP 5.0 25 – G Hysteresis Bhys – 10 – G BOP - BRP Min. Limits Typ. Max. Characteristic Units NOTES: 1. Typical Data is at TA = +25°C and VCC = 12 V and is for design information only. 2. 1 gauss (G) is exactly equal to 0.1 millitesla (mT). Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 4 A3240 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 o 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 oC 4.0 3.0 2.0 -50 OUTPUT ON, B > BOP OUTPUT OFF, B < BRP -25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE IN o C Dwg. GH-029-4 Dwg. GH-028-5 Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 5 A3240 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 = 150oC TA = -40oC 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 = 150oC TA = +25oC TA = -40oC 7.0 225 6.0 SUPPLY CURRENT IN mA SATURATION VOLTAGE IN mV IOUT = 20 mA TA = 150oC TA = +25oC TA = -40oC 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 Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 6 A3240 Chopper-Stabilized, Precision Hall-Effect Switch FUNCTIONAL DESCRIPTION SAMPLE & HOLD REG X B +V Dwg. EH-012 — HALL VOLTAGE + Dwg. AH-011-2 +V VCC OUTPUT VOLTAGE B RP B OP VOUT(SAT) 0 0 +B FLUX DENSITY Dwg. GH-007-2 SUPPLY 3 OUTPUT 2 PTCT www.allegromicro.com V CC 0.1 MF 1 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-and-hold 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. 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-and-Hold Signal Demodulator. Operation. The output of these devices switches low (turns on) when a magnetic field (south pole) perpendicular to the Hall sensor exceeds the operate point threshold (BOP). After turn-on, the output is capable of sinking 25 mA and the output voltage is VOUT(SAT). When the magnetic field is reduced below the release point (BRP), the device output goes high (turns off). 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 chopper-stabilization technique. 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 SUPPLY Dwg. EH-013 Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 7 X A3240 Chopper-Stabilized, Precision Hall-Effect Switch Package LH, 3-Pin (SOT-23W) +0.12 2.98 –0.08 1.49 D 3 +4° 4° –0° A +0.020 0.180–0.053 0.96 D +0.10 2.90 –0.20 +0.19 1.91 –0.06 2.40 0.70 D 0.25 MIN 1.00 2 1 0.55 REF 0.25 BSC 0.95 Seating Plane Gauge Plane 8X 10° REF B PCB Layout Reference View Branded Face 1.00 ±0.13 +0.10 0.05 –0.05 0.95 BSC 0.40 ±0.10 For Reference Only; not for tooling use (reference dwg. 802840) Dimensions in millimeters Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown A Active Area Depth, 0.28 mm REF 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 element, not to scale NNT 1 C Standard Branding Reference View N = Last two digits of device part number T = Temperature code Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 8 A3240 Chopper-Stabilized, Precision Hall-Effect Switch Package LT, 3-Pin (SOT89/TO-243AA) 4.50±0.10 +0.10 1.73 –0.11 2.50 2.00 A 2.24 0.80 1.14 +0.15 4.10 –0.16 +0.15 2.45 –0.16 +0.09 2.20 –0.07 2.60 +0.20 1.00 –0.11 1 2 3 4.60 Parting Line 1.00 +0.04 0.40 –0.05 0.70 1.50±0.10 2X 1.50 BSC 0.42±0.06 B 1.50 PCB Layout Reference View Basic pads for low-stress, not self-aligning Additional pad for low-stress, self-aligning Additional area for IPC reference layout 0.50±0.06 For Reference Only; not for tooling use (reference JEDEC. TO-243AA) Dimensions in millimeters Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown A Active Area Depth, 0.78 mm REF B C Reference land pattern layout (reference IPC7351 SOT89N); All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and PCB layout tolerances Branding scale and appearance at supplier discretion D Hall element, not to scale NNT 1 C Standard Branding Reference View = Supplier emblem N = Last two digits of device part number T = Temperature code Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 9 A3240 Chopper-Stabilized, Precision Hall-Effect Switch Package UA, 3-Pin SIP +0.08 4.09 –0.05 45° B C E 2.06 1.52 ±0.05 1.45 E Mold Ejector Pin Indent +0.08 3.02 –0.05 E Branded Face 45° 1 2.16 MAX D Standard Branding Reference View = Supplier emblem N = Last two digits of device part number T = Temperature code 0.79 REF A 0.51 REF NNT 1 2 3 +0.03 0.41 –0.06 15.75 ±0.51 For Reference Only; not for tooling use (reference DWG-9049) Dimensions in millimeters Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown A Dambar removal protrusion (6X) B Gate burr area C Active Area Depth, 0.50 mm REF +0.05 0.43 –0.07 D Branding scale and appearance at supplier discretion E Hall element, not to scale 1.27 NOM Copyright ©2000-2008, 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 Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 10