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Technical content
Description
The A1126 integrated circuit is an omnipolar, ultrasensitive Hall-effect switch with a digital output. This device has an integrated regulator permitting operation to 24 V . This device is especially suited for operation through 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 A1126 Hall-effect switch includes 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 omnipolar operation of the A1126 allows activation with either a north or a south polarity field of sufficient strength. In the absence of a magnetic field, the output is off. This patented magnetic-polarity–independence feature makes this device an excellent replacement for reed switches, with improved ease of manufacturing, because the A1126 does not A1126-DS Features and Benefits
- Omnipolar operation
- Low switchpoint drift
- Superior temperature stability
- Insensitive to physical stress
- Reverse battery protection
- Robust EMC capability
- Robust ESD protection Chopper Stabilized Omnipolar Hall-Effect Switch Functional Block Diagram Not to scale A1126 To all subcircuits GND VOUT Omnipolar Switchpoints Dynamic Offset Cancellation Amplifier Regulator VCC Control Signal Recovery Current Limit Continued on the next page… Packages: Approximate footprint 3-pin SOT23-W 2 mm × 3 mm × 1 mm (suffix LH) 3-pin ultramini SIP 1.5 mm × 4 mm × 3 mm (suffix UA)
Chopper Stabilized Omnipolar Hall-Effect SwitchA1126 2Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A. Pin-out Diagrams 3-pin SOT23W 3-pin SIP Absolute Maximum Ratings Characteristic Symbol Notes Rating Unit Forward Supply Voltage V CC 28 V Reverse Supply Voltage V RCC –18 V Output Off Voltage V OUT 28 V Reverse Supply Current I RCC –2 mA Continuous Output Current I OUT Internally limited – Operating Ambient Temperature T A L temperature range –40 to 150 ºC Maximum Junction Temperature T J(max) 165 ºC Storage Temperature T stg –65 to 170 ºC Terminal List Table Name Number Function LH UA VCC 1 1 Connects power supply to chip VOUT 2 3 Output from circuit GND 3 2 Ground require manufacturers to orient their magnets. These devices allow simple on/off switching in industrial, consumer, and automotive applications. The A1126 is rated for operation between the ambient temperatures –40°C to 150°C. The available package styles 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 leadframe. Description (continued) Selection Guide Part Number Packing 1 Package A1126LLHLT-T2 3,000 pieces per reel 3-pin SOT-23W surface mount A1126LLHLX-T 10,000 pieces per reel 3-pin SOT-23W surface mount A1126LUA-T 500 pieces per bag 3-pin ultramini SIP through-hole mount 1Contact Allegro® for additional packing options 2Available through authorized Allegro distributors only. 1 321 2
Chopper Stabilized Omnipolar Hall-Effect SwitchA1126 3Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. OPERATING CHARACTERISTICS Valid through TA and VCC ranges, TJ < TJ(max), CBYP = 0.1 μF; unless otherwise specified Characteristics Symbol Test Conditions Min. Typ. Max. Unit 1
Electrical Characteristics
Supply Voltage V CC Operating, TJ < 165°C 3 – 24 V Output Leakage Current I OUTOFF VOUT = 24 V, B < BRPS –– 1 0 μA Output On Voltage V OUT(SAT) IOUT = 20 mA, B > BOP – 185 500 mV Output Current Limit I OM B > BOP 30 – 60 mA Power-On Time2,3 tPO –– 2 5 μs Chopping Frequency f C – 800 – kHz Output Rise Time3,4 tr RLOAD = 820 Ω, CS = 20 pF – 0.2 2 μs Output Fall Time3,4 tf RLOAD = 820 Ω, CS = 20 pF – 0.1 2 μs Supply Current ICC(ON) B > BOP , VCC = 12 V – – 4 mA ICC(OFF) B < BRP , VCC = 12 V – – 4 mA Supply Zener Clamp Voltage V Z I CC = 6.5 mA; TA = 25°C 28 – – V Supply Zener Current I ZSUPPLY VS = 28 V – – 6.5 mA Magnetic Characteristics Operate Point BOPS South pole adjacent to branded face 15 38 55 G BOPN North pole adjacent to branded face -55 -38 -15 G Release Point BRPS South pole adjacent to branded face 5 20 50 G BRPN North pole adjacent to branded face -50 -20 -5 G Hysteresis B HYS | BOPS – BRPS |, | BOPN – BRPN |5 – 3 0 G 11 G (gauss) = 0.1 mT (millitesla). 2B < BRP (min) – 10 G , B > BOP (max) + 10 G. 3Guaranteed by device design and characterization. 4CS = oscilloscope probe capacitance.
Chopper Stabilized Omnipolar Hall-Effect SwitchA1126 4Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. Characteristic Performance Supply Current, ICC(OFF) (mA) Supply Voltage, VCC (V) TA = 150°C TA = –40°C TA = 25°C 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 Average Supply Current (Off) versus Supply Voltage 0 5 10 15 20 25 Ambient Temperature, TA (°C) Supply Current, ICC(OFF) (mA) -60 -40 -20 0 20 40 60 80 100 140 120 160 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 Ambient Temperature, TA (°C) -60 -40 -20 0 20 40 60 80 100 140 120 160 VCC = 3.0 V VCC = 24 V Average Supply Current (Off) versus Temperature TA = 150°CTA = –40°C TA = 25°C 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 5 10 15 20 25 Supply Voltage, VCC (V) Supply Current, ICC(ON) (mA) Average Supply Current (On) versus Supply Voltage VCC = 3.0 V VCC = 24 V 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 -60 -40 -20 0 20 40 60 80 100 140 120 160 Ambient Temperature, TA (°C) Supply Current, ICC(ON) (mA) Average Supply Current (On) versus Temperature
Chopper Stabilized Omnipolar Hall-Effect SwitchA1126 5Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. Release Point (BRP) Applied Flux Density (G) Supply Voltage, VCC (V) TA = 150°C TA = –40°C TA = 25°C Average Release Point (South) versus Supply Voltage 0 5 10 15 20 25 Ambient Temperature, TA (°C) Release Point (BRP) Applied Flux Density (G) -60 -40 -20 0 20 40 60 80 100 140 120 160 Ambient Temperature, TA (°C) -60 -40 -20 0 20 40 60 80 100 140 120 160 VCC = 3.0 V VCC = 24 V Average Release Point (South) versus Temperature TA = 150°CTA = –40°C TA = 25°C 0 5 10 15 20 25 Supply Voltage, VCC (V) Operate Point (BOP) Applied Flux Density (G) Average Operate Point (South) versus Supply Voltage VCC = 3.0 V VCC = 24 V -60 -40 -20 0 20 40 60 80 100 140 120 160 Ambient Temperature, TA (°C) Operate Point (BOP) Applied Flux Density (G) Average Operate Point (South) versus Temperature
Chopper Stabilized Omnipolar Hall-Effect SwitchA1126 6Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. Release Point (BRP) Applied Flux Density (G) Supply Voltage, VCC (V) TA = 150°C TA = –40°C –10 –15 –20 –25 –30 –35 –40 –45 –50 Average Release Point (North) versus Supply Voltage 0 5 10 15 20 25 TA = 25°C Ambient Temperature, TA (°C) Release Point (BRP) Applied Flux Density (G) -60 -40 -20 0 20 40 60 80 100 140 120 160 –10 –15 –20 –25 –30 –35 –40 –45 –50 Ambient Temperature, TA (°C) -60 -40 -20 0 20 40 60 80 100 140 120 160 VCC = 3.0 V VCC = 24 V Average Release Point (North) versus Temperature TA = 150°CTA = –40°C TA = 25°C –15 –20 –25 –30 –35 –40 –45 –50 –55 0 5 10 15 20 25 Supply Voltage, VCC (V) Operate Point (BOP) Applied Flux Density (G) Average Operate Point (North) versus Supply Voltage VCC = 3.0 V VCC = 24 V –15 –20 –25 –30 –35 –40 –45 –50 –55 -60 -40 -20 0 20 40 60 80 100 140 120 160 Ambient Temperature, TA (°C) Operate Point (BOP) Applied Flux Density (G) Average Operate Point (North) versus Temperature
Chopper Stabilized Omnipolar Hall-Effect SwitchA1126 7Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. -60 -40 -20 0 20 40 60 80 100 140 120 160 Ambient Temperature, TA (°C) Output Saturation Voltage VOUT(SAT), (mV) 500 450 400 350 300 250 200 150 100 Average Output Saturation Voltage versus Temperature IOUT = 20 mA, VCC = 12 V, B > BOP Switchpoint Hysteresis (BHYS) Applied Flux Density (G) Supply Voltage, VCC (V) TA = 150°C TA = –40°C Average Hysteresis (North) versus Supply Voltage 0 5 10 15 20 25 TA = 25°C Ambient Temperature, TA (°C) Switchpoint Hysteresis (BHYS) Applied Flux Density (G) -60 -40 -20 0 20 40 60 80 100 140 120 160 Ambient Temperature, TA (°C) -60 -40 -20 0 20 40 60 80 100 140 120 160 VCC = 3.0 V Average Hysteresis (North) versus Temperature VCC = 24 V TA = 150°C TA = –40°C TA = 25°C 0 5 10 15 20 25 Supply Voltage, VCC (V) Switchpoint Hysteresis (BHYS) Applied Flux Density (G) Average Hysteresis (South) versus Supply Voltage VCC = 3.0 V VCC = 24 V -60 -40 -20 0 20 40 60 80 100 140 120 160 Ambient Temperature, TA (°C) Switchpoint Hysteresis (BHYS) Applied Flux Density (G) Average Hysteresis (South) versus Temperature
Chopper Stabilized Omnipolar Hall-Effect SwitchA1126 8Allegro 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 Web site. 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 º C/W) 1-lay er PC B, Packa ge UA θJA = 228 ºC /W) 1-layer PCB, Pa ckage LH θJA = 110 ºC/ 2-layer PCB, Pa ckag e LH
Worcester, Massachusetts 01615-0036 U.S.A. vibration and electrical noise. field results in the device output high (off). and greater than BRPx ) will allow an indeterminate output state. Figure 1. Switching behavior of omnipolar switches. On the horizontal axis, the when using a circuit such as that shown in figure 2.
Chopper Stabilized Omnipolar Hall-Effect SwitchA1126 10Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A.
Application Information
Figure 2. Typical Application Circuit Figure 3. Concept of Chopper Stabilization Technique density logic integration and sample-and-hold circuits.
Chopper Stabilized Omnipolar Hall-Effect SwitchA1126 11Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. The device must be operated below the maximum junction temperature of the device, T J(max) . Under certain combina- tions of peak conditions, reliable operation may require derating supplied power or improving the heat dissipation properties of the application. This section presents a procedure for correlating factors affecting operating T J. (Thermal data is also available on the Allegro MicroSystems Web site.) 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. P D = VIN × IIN (1) T J = TA + ΔT (3) For example, given common conditions such as: TA= 25°C, VIN = 12 V, IIN = 4 mA, and RJA = 140 °C/W, then: P D = VIN × IIN = 12 V × 4 mA = 48 mW T = PD × RJA = 48 mW × 140 °C/W = 7°C A worst-case estimate, PD(max) , represents the maximum allow- able power level, without exceeding TJ(max) , at a selected RJA and TA. Example: Reliability for VCC at TA = 150°C, package UA, using a single-layer PCB. Observe the worst-case ratings for the device, specifically: RJA = 165 °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 ÷ 165 °C/W = 91 mW Finally, invert equation 1 with respect to voltage: VCC(est) = PD(max) ÷ ICC(max) = 91 mW ÷ 4 mA = 23 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 reliable 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 condi- tions. Power Derating
Chopper Stabilized Omnipolar Hall-Effect SwitchA1126 12Allegro 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 three digits of device part number NNN 2.90 +0.10 –0.20 4°±4° 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-2840) 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 Omnipolar Hall-Effect SwitchA1126 13Allegro 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 2.04 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 three digits of device part number NNN 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 Omnipolar Hall-Effect SwitchA1126 14Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. Copyright ©2010-2011, 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 Final September 22, 2011 Final release