A1171 ALLEGRO | Alldatasheet
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Description
The A1171 integrated circuit is an ultrasensitive, Hall effect switch with latched digital outputs and either unipolar or omnipolar magnetic actuation. It features operation at low supply currents and voltages, making it ideal for battery- operated electronics. The low operating supply voltage, 1.65 to 3.5 V , and unique clocking algorithm assist in reducing the average operating power consumption. For example, the power requirement is less than 15 μW with a 2.75 V supply. Unlike more traditional Hall effect switches, the A1171 allows the user to configure how the device is magnetically actuated. Under default conditions the device activates output switching with either a north or south polarity magnetic field of sufficient strength. The magnetic actuation can be set via an external selection pin to operate in a unipolar mode, switching only on a north or south polarity but not both. Furthermore, the output of the A1171 can be configured to switch either off or on in the absence of any significant magnetic field. Lastly, the A1171 has two push-pull output structures. This polarity-independence, as well as the minimal power requirements, allows the A1171 to easily replace reed switches, 1171-DS Features and Benefits ▪ 1.65 to 3.5 V battery operation ▪ Low supply current ▪ High sensitivity, BOP typically 30 G (3.0 mT) ▪ Operation with either north or south pole ▪ Configurable unipolar or omnipolar magnetic sensing ▪ Complementary, push-pull outputs ▪ Chopper stabilized ▫ Superior temperature stability ▫ Extremely low switchpoint drift ▫ Insensitive to physical stress ▪ Solid state reliability ▪ Small size Micropower Ultrasensitive Hall Effect Switch Continued on the next page… Package: 6 pin DFN/MLP (suffix EW) Functional Block Diagram Not to scale A1171 Dynamic Offset Cancellation VOUTPN VOUTPS VDD Low-Pass Filter Clock /Logic Latch Latch Logic Amp GND SELECT Sample and Hold and Averaging
Micropower Ultrasensitive Hall Effect SwitchA1171 Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A. providing superior reliability and ease of manufacturing while eliminating the requirement for signal conditioning. Improved stability is made possible through dynamic offset cancellation using chopper stabilization, which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress. This device includes, on a single silicon chip, a Hall-voltage generator, a small-signal amplifier, chopper stabilization, a latch, and a MOSFET output. The A1171 device offers a magnetically optimized solution, suitable for most applications. Package type EW (0.40 mm maximum height) offers a leadless surface mount solution. It is lead (Pb) free, with NiPdAu leadframe plating. Description (continued) Pin-out Diagram Absolute Maximum Ratings Characteristic Symbol Notes Rating Units Supply Voltage VDD 5 V Reverse Supply Voltage VRDD –0.3 V Magnetic Flux Density B Unlimited G Output Off Voltage VOUTPx 5 V Reverse Output Voltage VROUTPx –0.3 V Output Current IOUTPx(Source) 1 mA IOUTPx(Sink) –1 mA Operating Ambient Temperature TA Range E –40 to 85 ºC Maximum Junction Temperature TJ(max) 165 ºC Storage Temperature Tstg –65 to 170 ºC Terminal List Table Name Number Function VOUTPS 1 Push-pull output (selectable omnipolar activation or unipolar south pole activation) VOUTPN Push-pull output (selectable inverted omnipolar activation or unipolar north pole activation) SELECT 3 Sets activation mode for VOUTPx outputs; omnipolar output when tied to VDD or floating, unipolar output when grounded GND 4 Ground NC 5 No connection VDD 6 Connects power supply to chip PAD – Exposed pad for enhanced thermal dissipation VOUTPS VOUTPN SELECT VDD NC GND PAD Selection Guide Part Number Package Packing* A1171EEWLT-P DFN/MLP 1.5× mm; 0.40 mm maximum height 3000 pieces per 7 inch reel *Contact Allegro for additional packing options.
Micropower Ultrasensitive Hall Effect SwitchA1171 3Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. ELECTRICAL CHARACTERISTICS valid over operating voltage and temperature range (unless otherwise specified) Characteristic Symbol Test Conditions Min. Typ.1 Max. Units
Electrical Characteristics
Operating, TA= 5°C 1.65 – 3.5 V Operating, over full ambient temperature range 1.8 Output Voltage VOUT(SAT) NMOS on, ISINK = 1 mA, VDD = 3.5 V – 100 300 mV VOUT(HIGH) PMOS on, ISOURCE = –1 mA, VDD = 3.5 V VDD–300 VDD–100 – mV Mode Cycle Period tPeriod – 50 100 ms Chopping Frequency fC – 00 – kHz Supply Current IDD(EN) Device in awake mode (enabled) – – .0 mA IDD(DIS) Device in sleep mode (disabled) – – 8.0 µA IDD(AV) VDD = 1.8 V, TA = 5°C – 3.5 8 µA VDD = 3.5 V, TA = 5°C – 7.1 1 µA SELECT Current3 ISELECT 0 1 µA SELECT Voltage3 VSELECT(LOW) 0 – 1/3VDD V VSELECT(HIGH) /3VDD – VDD V 1Typical data are for initial design estimations only, and assume optimum manufacturing and application conditions, such as TA = 5°C. Performance may vary for individual units, within the specified maximum and minimum limits. Operate points, BOPX, and release points, BRPX, vary with supply voltage. 3Maximum VDD, minimum 0 V. MAGNETIC CHARACTERISTICS valid at 1.8 V ≤ VDD ≤ 3.5 V and TA = 5°C Characteristic Symbol Test Conditions Min. Typ.1 Max. Units2 Operate Point3 BOPS – 3 55 G BOPN –55 –3 – G Release Point3 BRPS 6 6 – G BRPN – –6 –6 G Hysteresis BHYS |BOPX - BRPX| – 6 – G 1Typical data are for initial design estimations only, and assume optimum manufacturing and application conditions, such as TA = 5°C. Performance may vary for individual units, within the specified maximum and minimum limits. 1 gauss (G) is exactly equal to 0.1 millitesla (mT). 3Operate points, BOPX, and release points, BRPX, vary with supply voltage.
Micropower Ultrasensitive Hall Effect SwitchA1171 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 -layer PCB, with 0.3 in. copper area each side 15 ºC/W 4-layer PCB, based on JEDEC standard 64 ºC/W *Additional thermal information available on Allegro Web site. 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 20 40 60 80 100 120 140 160 180 Temperature (°C) Power Dissipation, PD (mW) Power Dissipation versus Ambient Temperatur e EW package 4-layer PCB (RθJA = 64 ºC/W) EW package 2-layer PCB (RθJA = 125 ºC/W) Power Dissipation versus Ambient Temperature +B (South) –B (North) (Omnipolar configuration) (Unipolar configuration) Magnetic Field Output Pin (Activation Polarity) VOUTPS (South) VOUTPS VOUTPN (North) VOUTPN Output Polarity Diagram
Worcester, Massachusetts 01615-0036 U.S.A. pull-up transistor brings the output voltage to VOUT(HIGH). south polarity, is presented to the device. external mechanical vibration and electrical noise. is attained after the first excursion beyond BOPX or BRPX. Figure 1. Switching Behavior of Omnipolar Switches. On the horizontal axis, the B+ direction indicates increasing south polarity magnet- ic field strength, and the B– direction indicates decreasing south polarity field strength (including the case of increasing north polarity). This output switching profile applies when the SELECT line is allowed to float, selecting omnipolar operation.
Micropower Ultrasensitive Hall Effect SwitchA1171 6Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. Figure . Operation with Unipolar Mode Selected (SELECT Pin Grounded) BOPN BRPN BHYS VOUT(HIGH) VOUT VOUT(SAT) Switch to Low Switch to High B+B– BOPS BRPS BHYS VOUT(HIGH) VOUT VOUT(SAT) Switch to Low Switch to High B+B– (A) VOUTPN (B) VOUTPS SELECT Pin Settings Effect on Output Output Pin SELECT Pin Configuration Output Description Number Name
1 VOUTPS
Omnipolar output; ON with magnetic field of sufficient strength (B < BOPN or B > BOPS); OFF with low-strength or no magnetic field (BRPN < B < BRPS) Tied to ground Unipolar output; ON with south polarity magnetic field of sufficient strength (B > BOPS) VOUTPN Tied to VDD or floating Omnipolar output; OFF with magnetic field of sufficient strength (B < BOPN or B > BOPS); ON with low-strength or no magnetic field (BRPN < B < BRPS) Tied to ground Unipolar output; ON with north polarity magnetic field of sufficient strength (B < BOPN)
Micropower Ultrasensitive Hall Effect SwitchA1171 7Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. VDD NC VS GNDSELECT VOUTPN A1171 VOUTPS Sensor Outputs 0.1 µF CBYP VDD NC VS GNDSELECT VOUTPN A1171 VOUTPS Sensor Outputs 0.1 µF CBYP 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. As is shown in figure 3, a 0.1 μF capacitor is typical. Extensive applications information on magnets and Hall-effect sensors is available in the following notes:
- Hall-Effect IC Applications Guide, AN27701
- Hall-Effect Devices: Gluing, Potting, Encapsulating, Lead Welding and Lead Forming AN27703.1
- Soldering Methods for Allegro Products (SMD and Through- Hole), AN26009 All are provided in Allegro Electronic Data Book, AMS-702, and on the Allegro Web site, www.allegromicro.com.
Figure 3. Typical Application Circuits: (a) Omnipolar operation, and (b) Unipolar Operation
Applications
Worcester, Massachusetts 01615-0036 U.S.A. ating temperature and voltage ranges. of the output drift induced by thermal and mechanical stresses. The chopper stabilization technique uses a high frequency clock. where the sampling is performed at twice the chopper frequency. recoverability after temperature cycling. contact your Allegro sales representative. Figure 4. Chopper Stabilization Circuit (Dynamic Quadrature Offset Cancellation)
Micropower Ultrasensitive Hall Effect SwitchA1171 Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 U.S.A. Package EW, 6-pin DFN/MLP SEATING PLANE 0.38 0.50 0.25 0.70 1.10 1.10 0.30 0.70 1.575 0.50 1.25 0.325 0.325 2.00 1.50 C0.08 A A Terminal #1 mark area Active Area Depth B Exposed thermal pad (reference only, terminal #1 identifier appearance at supplier discretion) All dimensions nominal, not for tooling use (similar to JEDEC Type 1, MO-229”X2”BCD) Dimensions in millimeters Exact case and lead configuration at supplier discretion within limits shown C E Reference land pattern layout (reference IPC7351 SON50P200X200X100-9M); All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and PCB layout tolerances; when mounting on a multilayer PCB, thermal vias at the exposed thermal pad land can improve thermal dissipation (reference EIA/JEDEC Standard JESD51-5) E B Hall Element (not to scale) F F F F 0.75 1.00 PCB Layout Reference ViewC 0.15 D D Coplanarity includes exposed thermal pad and terminals Copyright ©2005-2007, 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 per- mit 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