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Description
The A3290 and A3291 Hall effect latches are extremely temperature-stable and stress-resistant sensor ICs, especially suited for operation over extended temperature ranges (up to 125°C). Superior high-temperature performance is made possible through Dynamic Offset Cancellation, which reduces the residual offset voltage normally caused by device package overmolding, temperature dependencies, and thermal stress. The two devices are identical except for their magnetic switchpoints. They are not intended for automotive applications. Both devices include, on a single silicon chip, a voltage regulator, a Hall-voltage generator, a small-signal amplifier, chopper stabilization, a Schmitt trigger, and a short-circuit protected open-drain output to sink up to 25 mA. A south polarity magnetic field of sufficient strength is required to turn the output on. A north polarity field of sufficient strength is necessary to turn the output off. An onboard regulator permits operation with supply voltages in the range of 4.2 to 24 V . Two package styles provide a magnetically optimized package for most applications. Type LH is a miniature SOT23W low- profile surface-mount package, and type UA is a three-pin ultramini SIP for through-hole mounting. Both packages are lead (Pb) free with 100% matte tin leadframe plating. A3290-DS, Rev. 9 Features and Benefits ▪ Symmetrical switchpoints ▪ Resistant to physical stress ▪ Superior temperature stability ▪ Output short-circuit protection ▪ Operation from unregulated supply ▪ Reverse battery protection ▪ Solid-state reliability ▪ Small package size Chopper Stabilized, Precision Hall Effect Latches for Consumer and Industrial Applications Functional Block Diagram A3290 and A3291 Amp Regulator Low-Pass Filter GND VCC OUT Control Current Limit Dynamic Offset Cancellation Sample and Hold Packages: Not to scale 3-pin SOT23W (suffix LH) 3-pin SIP (suffix UA)
Chopper Stabilized, Precision Hall Effect Latches for Consumer and Industrial Applications A3290 and A3291 2Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A. Selection Guide Part Number Packing 1 Package Type Magnetic Switchpoints* Operate, BOP (G) Release, BRP (G) A3290KLHLT-T 3000 pieces per 7-in. reel Surface mount SOT23W 5 to 50 –50 to –5A3290KUA-T 500 pieces per bulk bag Through hole ultramini SIP A3291KLHLT-T 3000 pieces per 7-in. reel Surface mount SOT23W 10 to 100 –100 to –10A3291KUA-T 500 pieces per bulk bag Through hole ultramini SIP *Algebraic convention used: (+) south polarity, (–) north polarity. Pin-out Diagrams Terminal List Name Number FunctionLH UA VCC 1 1 Power supply OUT 2 3 Output GND 3 2 Ground Package LH 1 32 PTCT 1 2 PTCT Package UA Absolute Maximum Ratings Characteristic Symbol Notes Rating Units Supply Voltage V CC 26.5 V Reverse Battery Voltage V RCC –30 V Output Off Voltage V OUT 26 V Continuous Output Current I OUT Device provides internal current limiting to help protect itself from output short circuits 25 mA Reverse Output Current I ROUT –50 mA Magnetic Flux Density B Unlimited G Operating Ambient Temperature T A Range K –40 to 125 ºC Maximum Junction Temperature T J(max) 165 ºC Storage Temperature T stg –65 to 170 ºC
Chopper Stabilized, Precision Hall Effect Latches for Consumer and Industrial Applications A3290 and A3291 3Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. ELECTRICAL CHARACTERISTICS over operating temperature range, unless otherwise noted Characteristic Symbol Test Conditions Min. Typ. 1 Max Units Supply Voltage Range2 VCC Operating, TJ < 165°C 4.2 – 24 V Output Leakage Current I OFF VOUT = 24 V, B < BRP –– 1 0 μA Output Saturation Voltage V OUT(SAT) IOUT = 20 mA, B > BOP – 185 500 mV Output Current Limit I ON B > BOP 30 – 60 mA Power-On Time t PO VCC > 4.2 V – – 50 μs Chopping Frequency f C – 800 – kHz Output Rise Time t R RLOAD = 820 Ω, CLOAD = 20 pF – 0.2 2.0 μs Output Fall Time t F RLOAD = 820 Ω, CLOAD = 20 pF – 0.1 2.0 μs Supply Current I CC B < BRP , VCC = 12 V – 3.0 8.0 mA B > BOP , VCC = 12 V – 4.0 8.0 mA Reverse Battery Current I RCC VRCC = –30 V – – –5.0 mA Zener Voltage V Z + VD ICC = 15 mA, TA = 25°C 28 – – V Zener Impedance Z Z + ZD ICC = 15 mA, TA = 25°C – 50 – Ω 1Typical data at TA = 25°C, 12 V. 2Maximum VCC must be derated for power dissipation and junction temperature. See application information. MAGNETIC CHARACTERISTICS1 over VCC range, unless otherwise noted Characteristic Symbol Test Conditions Min. Max. Units Operate Point2 BOP A3290 TA = 25°C and TA(max) 55 0 G TA = –40°C 55 0 G A3291 TA = 25°C and TA(max) 10 100 G TA = –40°C 10 100 G Release Point3 BRP A3290 TA = 25°C and TA(max) –50 –5 G A3291 TA = 25°C and TA(max) –100 –10 G TA = –40°C –100 –10 G Hysteresis (BOP – BRP) B HYS A3290 TA = 25°C and TA(max) 10 100 G TA = –40°C – 100 G A3291 TA = 25°C and TA(max) 20 200 G TA = –40°C – 200 G 1The positive polarity symbol (+) indicates south magnetic field, and the negative polarity symbol (–) indicates north magnetic field. 2Required polarity observed and transition of magnetic gradient through BOP . See functional description. 3Required polarity observed and transition of magnetic gradient through BRP after BOP . See functional description.
Chopper Stabilized, Precision Hall Effect Latches for Consumer and Industrial Applications A3290 and A3291 4Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information Characteristic Symbol Test Conditions* Value Units Package Thermal Resistance RθJA 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 *Additional thermal information available on Allegro website. 20 40 60 80 100 120 140 160 180 Temperature (ºC) Maximum Allowable VCC (V) Power Derating Curve (RQJA = 228 ºC/W) 1-layer PCB, Package LH (RQJA = 110 ºC/W) 2-layer PCB, Package LH (RQJA = 165 ºC/W) 1-layer PCB, Package UA VCC(min) VCC(max) 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 20 40 60 80 100 120 140 160 180 Temperature (°C) Power Dissipation, PD (mW) Power Dissipation versus Ambient Temperature θJA = 165 ºC/W) 1-layer PCB, Package UA θJA = 228 ºC/W) 1-layer θJA = 110 ºC/W) 2-layer PCB, Packag e LH
Worcester, Massachusetts 01615-0036 U.S.A. Figure 2. Chopper stabilization circuit (dynamic quadrature offset overmolding, temperature dependencies, and thermal stress. induced by the external magnetic flux. sampling frequency is used in order to process faster signals. Figure 3. Output voltage responds to sensed magnetic flux density. Figure 1. Hall element, basic circuit operation
Chopper Stabilized, Precision Hall Effect Latches for Consumer and Industrial Applications A3290 and A3291 6Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A.
Application Information
Note that these devices latch; that is, after a south (+) polarity magnetic field of sufficient strength impinging on the branded face of the device turns on the device, the device remains on until the magnetic field is reduced below the Release Point threshold, B RP . At that transition, the device output goes high (turns off). The difference in the magnetic operate and release points is the hysteresis, B HYS, of the device. This built-in hysteresis allows clean switching of the output, even in the presence of external mechanical vibration and electrical noise. When the devices are powered on, if the ambient magnetic field has an intensity that is between BOP and BRP , the initial output state is indeterminate. The first time that the level of B either rises through B OP , or falls through BRP , however, the correct output state is obatined. 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. This configuration is shown in figure 4. The simplest form of magnet that will operate these devices is a ring magnet.Other methods of operation, such as linear magnets, are possible. The device must be operated below the maximum junction temperature of the device, T J(max). Under certain combinations of peak conditions, reliable operation may require derating supplied power or improving the heat dissipation properties of the applica- tion. The Package Thermal Resistance, R JA, is a figure of merit summarizing the ability of the application and the device to dissi- pate 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, R JC, is relatively small component of RJA. Ambient air temperature, TA, and air motion are significant external factors, damped by overmolding. Sample power dissipation results are given in the Thermal Characteristics section. Additional thermal data is also available on the Allegro website. Extensive applications information for Hall-effect devices is available in: Hall-Effect IC Applications Guide, Application Note 27701 and Guidelines for Designing Subassemblies Using Hall- Effect Devices, Application Note 27703.1 Figure 4. Typical basic application circuit. A bypass capacitor is highly
Chopper Stabilized, Precision Hall Effect Latches for Consumer and Industrial Applications A3290 and A3291 7Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A.
0.55 REF
0.25 BSC
0.95 BSC
0.95 1.00 0.70 2.40 A Active Area Depth, 0.28 mm REF B C 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 Branding scale and appearance at supplier discretion A PCB Layout Reference View Branded Face C Standard Branding Reference View N = Last two digits of device part number T = Temperature code (letter) NNT N = Last three digits of device part number NNN 2.90 +0.10 –0.20 8X 10° REF 0.180+0.020 –0.053 0.05 +0.10 –0.05
0.25 MIN
1.91 +0.19 –0.06 2.98 +0.12 –0.08 1.00 ±0.13 0.40 ±0.10 4°±4° 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 D Hall element, not to scale D D D1.49 0.96
Chopper Stabilized, Precision Hall Effect Latches for Consumer and Industrial Applications A3290 and A3291 8Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. Package UA, 3-Pin SIP 231
0.79 REF
1.27 NOM
2.16 MAX 0.51 REF 45° C 45° B E E E 2.06 1.45 Gate burr area A B C Dambar removal protrusion (6X) A D E D Branding scale and appearance at supplier discretion Hall element, not to scale Active Area Depth, 0.50 mm REF 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 Standard Branding Reference View = Supplier emblem N = Last two digits of device part number T = Temperature code NNT Mold Ejector Pin Indent Branded Face 4.09 +0.08 –0.05 0.41 +0.03 –0.06 3.02 +0.08 –0.05 0.43 +0.05 –0.07 15.75 ±0.51 1.52 ±0.05
Chopper Stabilized, Precision Hall Effect Latches for Consumer and Industrial Applications A3290 and A3291 9Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. Copyright ©2005-2012, Allegro MicroSystems, Inc. Allegro MicroSystems, Inc. reserves the right to make, from time to time, such de par tures from the detail spec i fi ca tions as may be required to per- mit improvements in the per for mance, 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 in for ma tion in clud ed herein is believed to be ac cu rate and reliable. How ev er, Allegro MicroSystems, Inc. assumes no re spon si bil i ty for its use; nor for any in fringe ment 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
Revision History
Revision Revision Date Description of Revision Rev. 9 May 24, 2012 Update LH package branding