A3241ELHLT;A3241EUA;A3241EUA-T;A3241LLHLT;A3242ELHLT;中文规格书,Datasheet资料

Chopper-Stabilized Unipolar Hall-Effect Switches

Last Time Buy

This part is in production but has been determined to be

LAST TIME BUY. This classification indicates that the product is obsolete and notice has been given. Sale of this device is currently restricted to existing customer applications. The device should not be purchased for new design applications because of obsolescence in the near future. Samples are no longer available.Date of status change: January 31, 2011

Deadline for receipt of LAST TIME BUY orders: July 29, 2011

Recommended Substitutions:

For existing customer transition, and for new customers or new appli-cations, refer to the A1122.

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 respon-sibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use.

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A3241 and A3242

Chopper-Stabilized Unipolar Hall-Effect Switches

Features and Benefits

▪ Chopper stabilization

▫ Superior temperature stability▫ Extremely low switchpoint drift▫ Insensitive to physical stress▪ Reverse battery protection▪ Output short circuit protection▪ Solid state reliability▪ Small size

▪ Robust EMC capability▪ High ESD ratings (HBM)

Description

The A3241 and A3242 integrated circuits are unipolar Hall-effect switches with digital outputs. These devices are suited for operation over extended temperature ranges, up to +150°C. Superior high-temperature performance is made possible through an Allegro® patented dynamic offset cancellation, which reduces the residual offset voltage normally caused by device overmolding, temperature excursions, and thermal stress.

The A3241 and A3242 Hall-effect switches include the following on a single silicon chip: voltage regulator, Hall-voltage generator, small-signal amplifier, chopper stabilization, Schmitt trigger, and a short circuit protected open-drain output. Advanced BiCMOS wafer fabrication processing is used to take advantage of low-voltage requirements, component matching, very low input-offset errors, and small component geometries.

The integrated voltage regulator permits operation from 3.6 to 24 V. The unipolar family members operate with a sufficient south polarity field only, turning off in the absence of such a south polarity field.

Packages: 3 pin SOT23W (suffix LH), and 3 pin SIP (suffix UA)

Continued on the next page…

Not to scale

Functional Block Diagram

VCCRegulatorTo All SubcircuitsSample and HoldDynamic OffsetCancellationLow-PassFilterVOUTAmpAmpControlCurrent Limit<1Ω GNDA3241-DS, Rev. 16

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A3241 and A3242

Chopper-Stabilized Unipolar Hall Effect Switches

Description (continued)

The A3241 and A3242 are rated for operation between the ambient temperatures –40°C and 85°C for the E temperature range, and –40°C to 150°C for the L temperature range. The small geometries of the BiCMOS process allow these devices to be provided in ultrasmall packages. The package styles available provide magnetically

optimized solutions for most applications. Package LH is an SOT23W, a miniature low-profile surface-mount package, while package UA is a three-lead ultramini SIP for through-hole mounting. Each package is lead (Pb) free, with 100% matte tin plated leadframes.

Selection Guide

Part NumberA3242LLHLT-T2

Packing1

7-in. reel, 3000 pieces/reel

Mounting

3-pin SOT23W surface mount

Ambient, TA

(°C)–40 to 150

BRP(MIN)(G)110

BOP(MAX)

(G)200

1Contact Allegro for additional packing options.

2This device is in production, however, it has been deemed Pre-End of Life. The product is approaching end of life. Within a minimum of

6 months, the device will enter its fi nal, Last Time Buy, order phase. Status change: August 16, 2010. Recommended substitution: A1122.

Absolute Maximum Ratings

Characteristic

Supply Voltage

Reverse-Supply VoltageReverse-Supply CurrentOutput Off VoltageOutput CurrentMagnetic Flux Density

Operating Ambient TemperatureMaximum Junction TemperatureStorage Temperature

SymbolVCCVRCCIRCCVOUTIOUTSINK

BTATJ(max)Tstg

Range ERange L

Notes

Rating28–18–228

Internally Limited

Unlimited–40 to 85–40 to 150

165–65 to 170

UnitsVVmAV–GºCºCºCºC

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000www.allegromicro.com

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A3241 and A3242

Chopper-Stabilized Unipolar Hall Effect Switches

OPERATING CHARACTERISTICS valid over full operating voltage and ambient temperature ranges, unless otherwise noted

Characteristic

Electrical CharacteristicsSupply Voltage1

Output Leakage CurrentOutput On VoltageOutput Current LimitPower-On TimeChopping FrequencyOutput Rise Time2Output Fall Time2Supply Current

Reverse Battery CurrentSupply Zener Clamp VoltageSupply Zener Current3Magnetic Characteristics4Operate PointRelease PointHysteresis

2 C

SymbolVCCIOUTOFFVOUT(SAT)

IOMtPOfctrtfICCONICCOFFIRCCVZSupplyIZSupply

Test Conditions

Operating, TJ < 165°CVOUT = 24 V, B < BRPIOUT = 20 mA, B > BOPB > BOPVCC > VCC(MIN)

RLOAD = 820 Ω, CS = 20 pFRLOAD = 820 Ω, CS = 20 pFB > BOPB < BRPVRCC = –18 V

ICC = 6.5 mA; TA = 25°CVS = 28 VA3241A3242A3241A3242A3241A3242

BOP – BRP

Min.3.6––30–––––––28–50120401101010

Typ.–––––200––1.51.5–––95150701252525

Max.24105006050–113.53.5–2–6.51352001101904240

UnitsVμAmVmAμskHzμsμsmAmAmAVmA

GGGGGG

BOPBRPBHYS

1 Maximum voltage must be adjusted for power dissipation and junction temperature, see Power Derating section.S = oscilloscope probe capacitance.

3 Maximum current limit is equal to the maximum I

CC(MAX) + 3 mA.

4 Magnetic fl ux density, B, is indicated as a negative value for north-polarity magnetic fi elds, and as a positive value for south-polarity magnetic fi elds.

This so-called algebraic convention supports arithmetic comparison of north and south polarity values, where the relative strength of the fi eld is indicated by the absolute value of B, and the sign indicates the polarity of the fi eld (for example, a –100 G fi eld and a 100 G fi eld have equivalent strength, but opposite polarity).

DEVICE QUALIFICATION PROGRAM

Contact Allegro for information.

EMC (Electromagnetic Compatibility) REQUIREMENTS

Contact Allegro for information.

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000www.allegromicro.com

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A3241 and A3242

Chopper-Stabilized Unipolar Hall Effect Switches

Characteristic Data

Supply Current (On) versus Ambient Temperature5.04.0ICCON (mA)Supply Current (On) versus Supply Voltage5.04.0VCC (V)243.63.02.01.0 0TA (°C)–4025150ICCON (mA)3.02.01.00.0-50050TA (°C)1001500510VCC (V)152025Supply Current (Off) versus Ambient Temperature5.04.0ICCOFF (mA)ICCOFF (mA)Supply Current (Off) versus Supply Voltage5.04.0VCC (V)243.63.02.01.0 0TA (°C)-40°C–4025°C25150°C1503.02.01.00.0-50050TA (°C)1001500510VCC (V)152025Output Voltage (On) versus Ambient Temperature500450400VOUT(SAT) (mV)Output Voltage (On) versus Supply Voltage500450400VCC (V)243.6VOUT(SAT) (mV)350300250200150100500-50050TA (°C)1001503503002502001501005000510VCC (V)152025TA (°C)150°C–4025°C25-40°C150Continued on the next page... Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000www.allegromicro.com

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A3241 and A3242

Chopper-Stabilized Unipolar Hall Effect Switches

Operate Point versus Ambient Temperature(A3241)130120110BOP (G)BOP (G)Operate Point versus Supply Voltage(A3241)130120110VCC (V)243.610090807060500510VCC (V)152025TA (°C)–40251501009080706050-50050TA (°C)100150Release Point versus Ambient Temperature(A3241)11010090BRP (G)BRP [G]Release Point versus Supply Voltage(A3241)11010090VCC (V)243.68070605040TA (°C)–40251508070605040-50050TA (°C)1001500510VCC (V)152025Hysteresis versus Ambient Temperature(A3241)4035BHYS (G)BHYS (G)Hysteresis versus Supply Voltage(A3241)4035VCC (V)243.63025201510TA (°C)–40251503025201510-50050TA (°C)1001500510VCC (V)152025Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000www.allegromicro.com

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A3241 and A3242

Chopper-Stabilized Unipolar Hall Effect Switches

Operate Point versus Ambient Temperature(A3242)200190180BOP (G)BOP (G)Operate Point versus Supply Voltage(A3242)200190180VCC (V)243.6170160150140130120TA (°C)–4025150170160150140130120-50050TA (°C)1001500510VCC (V)152025Release Point versus Ambient Temperature(A3242)190180170VCC (V)243.6BRP (G)BRP (G)Release Point versus Supply Voltage(A3242)190180170160150140130120110TA (°C)–4025150160150140130120110-50050TA (°C)1001500510VCC (V)152025Hysteresis versus Ambient Temperature(A3242)403530BHYS (G)Hysteresis versus Supply Voltage(A3242)4035VCC (V)243.630BHYS (G)25201510-50050TA (°C)100150252015100510VCC (V)152025TA (°C)–4025150Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000www.allegromicro.com

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A3241 and A3242

Chopper-Stabilized Unipolar Hall Effect Switches

THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information

Characteristic

Symbol

Test Conditions

Package LH-3, 1-layer PCB with copper limited to solder pads

Package LH-3, 2-layer PCB with 0.926 in2 on each side, connected by thermal vias

Package UA, 1-layer PCB with copper limited to solder pads

Value110228165

UnitsºC/WºC/WºC/W

Package Thermal Resistance

RθJA

Power Derating Curve252423222120191817161514131211109876543220VCC(max)Maximum Allowable VCC (V)1-layer PCB, Package LH = 110 °C/W) (RθJA1-layer PCB, Package UA = 165 °C/W)(RθJA2-layer PCB, Package LH = 228 °C/W) (RθJAVCC(min)406080100120140160180Temperature (°C)Power Dissipation versus Ambient Temperature

1900180017001600150014001300120011001000900800700600500400300200100020Power Dissipation, PD (mW)1-l(Rayer PθJCA = 11B, P0 ºCack1-la/yWage(Rer P) LHCBθJA= 16, Pa5 ºCcka/W)ge UA2-lay(Rer PCBθJA= 228, Package L ºC/W)H406080100120Temperature (°C)140160180 Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000www.allegromicro.com

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A3241 and A3242

Chopper-Stabilized Unipolar Hall Effect Switches

Functional Description

Operation

The output of these devices switches low (turns on) when a magnetic fi eld (south polarity) perpendicular to the Hall ele-ment exceeds the operate point threshold, BOP. After turn-on, the output voltage is VOUT(SAT). The output transistor is capable of sinking current up to the short circuit current limit, IOM, which is a minimum of 30 mA. When the magnetic fi eld 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.

Powering-on the device in the hysteresis region, less than BOP and higher than BRP, allows an indeterminate output state. The correct state is attained after the fi rst excursion beyond BOP or BRP.

Applications

It is strongly recommended that an external bypass capacitor be connected (in close proximity to the Hall element) between the supply and ground of the device to reduce both external noise and noise generated by the chopper stabilization technique. As is shown in Panel B of fi gure 1, a 0.1μF capacitor is typical. Extensive applications information on magnets and Hall-effect devices is available in:

• Hall-Effect IC Applications Guide, AN27701,

• Hall-Effect Devices: Gluing, Potting, Encapsulating, Lead Welding and Lead Forming, AN27703.1

• Soldering Methods for Allegro’s Products – SMT and Through-Hole, AN26009

All are provided in Allegro Electronic Data Book, AMS-702 and the Allegro Web site: www.allegromicro.com

(A)

V+VS(B)

VCCSwitch to HighVCCCBYP0.1 µFRLOADOutputSwitch to LowVCCA324xVOUTVOUT(SAT)0GNDBRPB–0B+BOPBHYSFigure 1: Switching Behavior of Unipolar Switches. In Panel A, on the horizontal axis, the B+ direction indicates increasing south polarity magnetic fi eld strength, and the B– direction indicates decreasing south polarity fi eld strength (including the case of increasing north polarity). This behavior can be exhibited when using a circuit such as that shown in panel B.

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000www.allegromicro.com

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A3241 and A3242

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 element. This makes it diffi cult to process the signal while maintaining an accurate, reliable output over the specifi ed oper-ating 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 modulation-demodulation process. The undesired offset signal is separated from the magnetic-fi eld-induced signal in the frequency domain, through modulation. The subsequent demodulation acts as a modulation process for the offset, causing the magnetic-fi eld-induced signal to recover its original spectrum at baseband, while the DC offset becomes a high-frequency signal. The magnetic-fi eld-induced signal then can pass through a low-pass fi lter, while the modulated DC offset is suppressed. This con-fi guration is illustrated in fi gure 2.

The chopper stabilization technique uses a 200 kHz high-fre-quency clock. For demodulation process, a sample and hold

technique is used, where the sampling is performed at twice the chopper frequency (400 kHz). This high-frequency operation allows a greater sampling rate, which results in higher accuracy and faster signal-processing capability. This approach desensi-tizes 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 amplifi ers in combination with high-density logic integration and sample-and-hold circuits.

The repeatability of magnetic-fi eld-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 fi elds; for

example, speed sensing of ring-magnet targets. For such applica-tions, Allegro recommends its digital device families with lower sensitivity to jitter. For more information on those devices, contact your Allegro sales representative.

RegulatorClock/LogicHall ElementAmpSample andHoldFigure 2. Chopper Stabilization Circuit (Dynamic Quadrature Offset Cancellation)

Low-PassFilterAllegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000www.allegromicro.com

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分销商库存信息:

ALLEGROA3241ELHLTA3241LLHLTA3242EUAA3242LUA-TA3241ELHLT-T

A3241EUAA3242ELHLTA3242EUA-TA3241LLHLT-TA3241LUA-T

A3241EUA-TA3242ELHLT-TA3242LLHLTA3242LLHLT-T