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Description
The A1120 and A1125 Hall-effect, unipolar switches are extremely temperature-stable and stress-resistant sensor ICs, 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. Each 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. An on-board regulator permits operation with supply voltages of 3 to 24 V . The advantage of operating down to 3 V is that the device can be used in 3 V applications or with additional external resistance in series with the supply pin for greater protection against high voltage transient events. For the A1120, a south pole of sufficient strength turns the output on. Removal of the magnetic field turns the output off. The A1125 is complementary to the A1120 in that, for the A1125, a south pole turns the output off, and removal of the magnetic field turns the output on. Two package styles provide a magnetically optimized package for most applications. Package type LH is a modified SOT23W, surface mount package, while UA is a three-lead ultra-mini SIP for through-hole mounting. Each package type is lead (Pb) free (suffix, –T), with a 100% matte tin plated leadframe. A1120-DS, Rev. 9 Features and Benefits ▪ Unipolar switchpoints ▪ Resistant to physical stress ▪ Superior temperature stability ▪ Output short-circuit protection ▪ Operation from unregulated supply ▪ Reverse battery protection ▪ Solid-state reliability ▪ Small package sizes Chopper Stabilized Precision Hall Effect Switches Packages: Functional Block Diagram Not to scale A1120 and A1125 3-pin SOT23W (suffix LH) 3-pin SIP (suffix UA) Regulator GND VCC VOUT Control Current Limit Dynamic Offset Cancellation Sample and Hold To All Subcircuits Amp Low-Pass Filter
Chopper Stabilized Precision Hall Effect SwitchesA1120 and A1125 2Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A. Absolute Maximum Ratings Characteristic Symbol Notes Rating Units Forward Supply Voltage V CC 26.5 V Reverse Supply Voltage V RCC –30 V Output Off Voltage V OUT 26 V Continuous Output Current I OUT 25 mA Reverse Output Current I ROUT –50 mA Operating Ambient Temperature T A Range E –40 to 85 ºC Range L –40 to 150 ºC Maximum Junction Temperature T J(max) 165 ºC Storage Temperature T stg –65 to 170 ºC Pin-out Diagrams Terminal List Name Description Number Package LH Package UA VCC Connects power supply to chip 1 1 VOUT Output from circuit 2 3 GND Ground 3 2 1 32GND VOUT VCC Package UAPackage LH 1 2
3 GND
Part Number Packing 1 Mounting Ambient, T A Output In South (Positive) Magnetic Field A1120ELHLX-T 13-in. reel, 10000 pieces/reel 3-pin SOT23W surface mount –40ºC to 85ºC On (logic low) A1120ELHLT-T2 7-in. reel, 3000 pieces/reel 3-pin SOT23W surface mount A1120EUA-T Bulk, 500 pieces/bag 3-pin SIP through hole A1120LLHLX-T 13-in. reel, 10000 pieces/reel 3-pin SOT23W surface mount –40ºC to 150ºCA1120LLHLT-T 2 7-in. reel, 3000 pieces/reel 3-pin SOT23W surface mount A1120LUA-T Bulk, 500 pieces/bag 3-pin SIP through hole A1125ELHLX-T 13-in. reel, 10000 pieces/reel 3-pin SOT23W surface mount –40ºC to 85ºC Off (logic high) A1125EUA-T Bulk, 500 pieces/bag 3-pin SIP through hole A1125LLHLX-T 13-in. reel, 10000 pieces/reel 3-pin SOT23W surface mount –40ºC to 150ºC A1125LUA-T Bulk, 500 pieces/bag 3-pin SIP through hole *Contact Allegro for additional packing options. 2Available through authorized Allegro distributors only.
Chopper Stabilized Precision Hall Effect SwitchesA1120 and A1125 3Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. ELECTRICAL CHARACTERISTICS Valid valid over full operating voltage and ambient temperature ranges; unless otherwise noted Characteristics Symbol Test Conditions Min. Typ. 1 Max. Unit 2
Electrical Characteristics
Forward Supply Voltage V CC Operating, TJ < 165°C 3 – 24 V Output Leakage Current I OUTOFF A1120 V OUT = 24 V, B < BRP –– 1 0 μA A1125 V OUT = 24 V, B > BOP –– 1 0 μA Output Saturation Voltage V OUT(SAT) A1120 I OUT = 20 mA, B > BOP – 185 500 mV A1125 I OUT = 20 mA, B < BRP – 185 500 mV Output Current Limit I OM A1120 B > B OP 30 – 60 mA A1125 B < B RP 30 – 60 mA Power-On Time3 tPO VCC > 3.0 V, B < BRP(min) – 10 G, B > BOP(max) + 10 G –– 2 5 μs Chopping Frequency f C – 800 – kHz Output Rise Time3,4 tr RL = 820 Ω, CS = 20 pF – 0.2 2 μs Output Fall Time3,4 tf RL = 820 Ω, CS = 20 pF – 0.1 2 μs Supply Current ICC(ON) A1120 V CC = 12 V, B > BOP ––4m A A1125 V CC = 12 V, B < BRP ––4m A ICC(OFF) A1120 V CC = 12 V, B < BRP ––4m A A1125 V CC = 12 V, B > BOP ––4m A Reverse Supply Current I RCC VRCC = –30 V – – –5 mA Supply Zener Clamp Voltage V Z ICC = 5 mA; TA = 25°C 28 – – V Zener Impedance I Z ICC = 5 mA; TA = 25°C – 50 – Ω Magnetic Characteristics Operate Point B OP A1120 – 35 50 G A1125 – 35 50 G Release Point B RP A1120 5 25 – G A1125 5 25 – G Hysteresis B HYS (BOP – BRP)– 1 0 – G 1Typical data are are at TA = 25°C and VCC = 12 V, and are for initial design estimations only. 21 G (gauss) = 0.1 mT (millitesla). 3Guaranteed by device design and characterization. 4CS = oscilloscope probe capacitance.
Chopper Stabilized Precision Hall Effect SwitchesA1120 and A1125 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 20 40 60 80 100 120 140 160 180 Maximum Allowable VCC (V) TJ(max) = 165ºC; ICC = ICC(max) Power Derating Curve (RQJA = 228 ºC/W) Package LH, 1-layer PCB (RQJA = 110 ºC/W) Package LH, 2-layer PCB (RQJA = 165 ºC/W) Package UA, 1-layer PCB 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 QJA = 165 ºC/W) Package UA, 1-layer PCB QJA = 228 ºC/W) Package LH, 1-layer PCB QJA = 110 ºC/W) Package LH, 2-layer PCB
Chopper Stabilized Precision Hall Effect SwitchesA1120 and A1125 5Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. CBYP A1125 A1120 VOUT GND0.1 μF VCC Output RL VS Operation The output of the A1120 devices switches low (turns on) when a magnetic field perpendicular to the Hall element exceeds the operate point threshold, B OP (see panel A of figure 1). When the magnetic field is reduced below the release point, BRP , the device output goes high (turns off). The output of the A1125 devices switches high (turns off) when a magnetic field perpendicular to the Hall element exceeds the operate point threshold, B OP (see panel B of figure 1). When the magnetic field is reduced below the release point, B RP , the device output goes low (turns on). After turn-on, the output voltage is VOUT(SAT) . The output tran- sistor is capable of sinking current up to the short circuit current limit, I OM, which is a minimum of 30 mA. 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 range (less than BOP and higher than BRP) will give an indeterminate output state. The correct state is attained after the first 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 external noise in the application. As is shown in panel B of figure 1, a 0.1 μF capacitor is typical. Extensive applications information for Hall effect devicers is available in:
- Hall-Effect IC Applications Guide, Application Note 27701
- Guidelines for Designing Subassemblies Using Hall-Effect Devices, Application Note 27703.1
- Soldering Methods for Allegro’ s Products – SMT and Through- Hole, Application Note 26009 All are provided in Allegro Electronic Data Book, AMS-702, and the Allegro Web site, www.allegromicro.com.
Figure 1. Device switching behavior. In panels A and B, on the horizontal axis, the B+ direction indicates increasing south polarity magnetic field strength. This behavior can be exhibited when using an electrical circuit such as that shown in panel C.
Worcester, Massachusetts 01615-0036 U.S.A. temperature and voltage ranges. of the output drift induced by thermal and mechanical stresses. Allegro sales representative. Figure 2. Model of chopper stabilization technique
Chopper Stabilized Precision Hall Effect SwitchesA1120 and A1125 7Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. Power Derating 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 appli- cation. This section presents a procedure for correlating factors affecting operating T J. (Thermal data is also available on the Allegro MicroSystems website.) The Package Thermal Resistance, RJA, is a figure of merit sum- marizing 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, R JC, is relatively small component of RJA. 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 T J, at PD. PD = VIN × IIN (1) T J = TA + ΔT (3) For example, given common conditions such as: TA= 25°C, VCC = 12 V, ICC = 1.6 mA, and RJA = 165 °C/W, then: P D = VCC × ICC = 12 V × 1.6 mA = 19 mW T = PD × RJA = 19 mW × 165 °C/W = 3°C A worst-case estimate, PD(max), represents the maximum allow- able power level (VCC(max), ICC(max)), without exceeding TJ(max), at a selected RJA and TA. Example: Reliability for VCC at TA = 150°C, package LH, using a minimum-K PCB. Observe the worst-case ratings for the device, specifically: RJA = 228°C/W, TJ(max) = 165°C, VCC(max) = 24 V , and ICC(max) = 4 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 ÷ RJA = 15°C ÷ 228 °C/W = 66 mW Finally, invert equation 1 with respect to voltage: VCC(est) = PD(max) ÷ ICC(max) = 66 mW ÷ 4 mA = 16.5 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 reli- able operation between VCC(est) and VCC(max) requires enhanced RJA. If VCC(est) ≥ VCC(max), then operation between VCC(est) and VCC(max) is reliable under these conditions.
Chopper Stabilized Precision Hall Effect SwitchesA1120 and A1125 8Allegro 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 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 Standard Branding Reference View Branded Face N = Last two digits of device part number T = Temperature code NNT 2.90 +0.10 –0.20 4° +4° –0° 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 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 Package LH, 3-Pin (SOT-23W)
Chopper Stabilized Precision Hall Effect SwitchesA1120 and A1125 9Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. Copyright ©2009, 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 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 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 2.04 1.44 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