(A1145 / A1146) Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

A1145 and A1146 Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches Features and Benefits ▪ Chopper stabilization ▫ Low switchpoint drift over operating temperature range ▫ Low sensitivity to stress ▪ Factory programmed at end-of-line for optimized switchpoints ▪ On-chip protection ▫ Supply transient protection ▫ Reverse-battery protection ▫ On-board voltage regulator ▫ 3.5 to 24 V operation Description The A1145 and A1146 devices are two-wire, unipolar, Hall effect switches that are factory-programmed at end-of-line to optimize ultrasensitive magnetic switchpoint accuracy. These devices use a patented high frequency chopper-stabilization technique, produced using the Allegro advanced BiCMOS wafer fabrication process, to achieve magnetic stability and to eliminate offset inherent in single-element devices exposed to harsh application environments. Commonly found in a number of automotive applications, these switches are utilized to sense seat track position, seat belt buckle presence, hood/trunk latching, and shift selector position. Two-wire unipolar switches, such as the A1145 and A1146, are particularly advantageous in price-sensitive applications because they require one less wire for operation than do switches with the more traditional open-collector output. Additionally, the system designer inherently gains diagnostics because there is always output current flowing, which should be in either of two narrow ranges. Any current level not within these ranges indicates a fault condition. These devices also Packages: 3 pin SOT23W (suffix LH), and 3 pin SIP (suffix UA) www.DataSheet4U.com Continued on the next page… Not to scale V+ Functional Block Diagram VCC Regulator To All Subcircuits 0.01 uF Dynamic Offset Cancellation Clock/Logic Sample and Hold Low-Pass Filter Amp GND Package UA Only GND A1145-DS, Rev. 8 A1145 and A1146 Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches field of sufficient strength, and switch HIGH otherwise. Both versions are offered in two package styles. The LH is a SOT23W, miniature low-profile package for surface-mount applications. The UA is a three-lead ultramini SIP for through-hole mounting. Each package is available in a lead (Pb) free version (suffix, –T) with 100% matte tin plated leadframe. Field-programmable versions also available: A1185 and A1186. Description (continued) feature on-chip transient protection and a Zener clamp to protect against overvoltage conditions on the supply line. The output currents of the A1146 switches HIGH in the presence of a south (+) polarity magnetic field of sufficient strength, and switches LOW otherwise, as in the presence of a weak field or a north (–) polarity field. The A1145 has an opposite output: the currents switch LOW in the presence of a south-polarity magnetic Selection Guide Part Number A1145ELHLT-T A1145EUA-T A1145EUATI A1145EUATI-T A1145LLHLT-T A1145LUA-T A1145LUATI A1145LUATI-T A1146ELHLT-T A1146EUA-T A1146EUATI A1146EUATI-T A1146LLHLT-T A1146LUA-T A1146LUATI A1146LUATI-T 1Pb-based Pb-Free1 Yes Yes – Yes Yes Yes – Yes Yes Yes – Yes Yes Yes – Yes Packing2 Tape and Reel, 3000 pieces/reel Bulk Bag, 500 pieces/bag Tape and Reel, 2000 pieces/reel Tape and Reel, 3000 pieces/reel Bulk Bag, 500 pieces/bag Tape and Reel, 2000 pieces/reel Tape and Reel, 3000 pieces/reel Bulk Bag, 500 pieces/bag Tape and Reel, 2000 pieces/reel Tape and Reel, 3000 pieces/reel Bulk Bag, 500 pieces/bag Tape and Reel, 2000 pieces/reel Package Surface Mount Through Hole Surface Mount Through Hole Surface Mount Through Hole Surface Mount Through Hole Operating Ambient Temperature, TA (°C) Output Level in South (+) Field3 –40 to 85 Low –40 to 150 –40 to 85 High –40 to 150 variants are being phased out of the product line. Certain variants cited in this footnote are in production but have been determined to be LAST TIME BUY. This classification indicates that sale of this device is currently restricted to existing customer applications. The device should not be purchased for new design applications because obsolescence in the near future is probable. Samples are no longer available. Status change: October 31, 2006. Deadlilne for receipt of LAST TIME BUY ORDERS: April 27, 2007. These variants include: A1145ELHLT, A1145EUA, A1145LLHLT, A1145LUA, A1146ELHLT, A1146EUA, A1146LLHLT, and A1146LUA. 2Contact Allegro for additional packing options. 3South (+) magnetic fields must be of sufficient strength. Absolute Maximum Ratings Characteristic Supply Voltage Reverse Supply Voltage Magnetic Flux Density Operating Ambient Temperature Maximum Junction Temperature Storage Temperature Symbol VCC VRCC B TA TJ(max) Tstg Range E Range L Notes Rating 28 –18 Unlimited –40 to 85 –40 to 150 165 –65 to 170 Units V V G ºC ºC ºC ºC Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 2 A1145 and A1146 Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches Symbol VCC ICCL ICCH IRCC VZSUPPLY IZSUPPLY di/dt fC ton POS CBYPASS = 0.01 μF ELECTRICAL CHARACTERISTICS over the operating voltage and temperature ranges, unless otherwise specified Characteristic Supply Voltage1 Supply Current2 Reverse Supply Current Supply Zener Clamp Voltage Supply Zener Clamp Current3 Output Slew Rate4 Chopping Frequency Power-On Time5 Power-On State6,7 1V CC represents 2Relative values Test Conditions Min. 3.5 Typ. – – – – – – 36 200 – HIGH Max. 24 6.9 17 –1.6 40 9.9 – – 25 – Units V mA mA mA V mA mA/μs kHz μs – B > BOP for A1145; B < BRP for A1146 B > BOP for A1146; B < BRP for A1145 VRCC = –18 V ICC = ICCL(max) + 3 mA; TA = 25°C VZSUPPLY = 28 V Capacitance of the oscilloscope performing the measurement = 20 pF 5 12 – 28 – – – – – t < ton; VCC slew rate > 25 mV/μs the generated voltage between the VCC pin and the GND pin. of B use the algebraic convention, where positive values indicate south magnetic polarity, and negative values indicate north magnetic polarity; therefore greater B values indicate a stronger south polarity field (or a weaker north polarity field, if present). 3I ZSUPPLY(max) = ICCL(max) + 3 mA. 4Measured without bypass capacitor between VCC and GND. Use of a bypass capacitor results in slower current change. 5Measured with and without bypass capacitor of 0.01 μF. Adding a larger bypass capacitor causes longer Power-On Time. 6POS is defined as true only with a V CC slew rate of 25 mV / μs or greater. Operation with a VCC slew rate less than 25 mV / μs can permanently harm device performance. 7POS is undefined for t > t or B on RP < B < BOP . MAGNETIC CHARACTERISTICS over the operating voltage and temperature ranges, unless otherwise specified Characteristic Operate Point Symbol BOP A1145 A1146 A1145 A1146 Test Conditions ICC = ICCL ICC = ICCH ICC = ICCH ICC = ICCL Min. 20 Typ.* 37 Max. 60 Units G Release Point Hysteresis BRP BHYS 10 5 22 15 55 30 G G BHYS = BOP – BRP *Typical data are for initial design estimations only, and assume optimum manufacturing and application conditions, such as TA = 25°C and VCC = 12 V. Performance may vary for individual units, within the specified maximum and minimum limits. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 3 A1145 and A1146 Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches Characteristic Data Supply Current (Low) versus Ambient Temperature at Various Levels of VCC (A1145 and A1146) 10 8 Supply Current (High) versus Ambient Temperature at Various Levels of VCC (A1145 and A1146) 20 18 VCC 3.5 V 12.0 V 24.0 V ICCH (mA) ICCL (mA) 6 4 2 0 –50 16 14 12 10 –50 VCC 3.5 V 12.0 V 24.0 V 0 50 100 150 200 0 50 100 150 200 Ambient Temperature, TA (°C) Ambient Temperature, TA (°C) Operate Point versus Ambient Temperature at Various Levels of VCC (A1145 and A1146) 70 60 50 Switchpoint Hysteresis versus Ambient Temperature at Various Levels of VCC (A1145 and A1146) 40 35 VCC BHYS (G) 3.5 V 12.0 V 24.0 V 30 25 20 15 10 5 VCC 3.5 V 12.0 V 24.0 V BOP (G) 40 30 20 10 0 –50 0 50 100 150 200 0 –50 0 50 100 150 200 Ambient Temperature, TA (°C) Ambient Temperature, TA (°C) Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 4 A1145 and A1146 Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches Symbol Test Conditions* Package LH, 1-layer PCB with copper limited to solder pads Package LH, 2-layer PCB with 0.463 in.2 of copper area each side connected by thermal vias Package UA, 1-layer PCB with copper limited to solder pads Value Units 228 110 165 ºC/W ºC/W ºC/W THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information Characteristic Package Thermal Resistance RθJA *Additional thermal information available on Allegro Web site. Power Derating Curve 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 20 VCC(max) Maximum Allowable VCC (V) 2-layer PCB, Package LH (RθJA = 110 ºC/W) 1-layer PCB, Package UA (RθJA = 165 ºC/W) 1-layer PCB, Package LH (RθJA = 228 ºC/W) VCC(min) 120 140 160 180 40 60 80 100 Temperature (ºC) Power Dissipation versus Ambient Temperature 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 20 Power Dissipation, PD (m W) 2l (R aye rP θJ C A= 11 B, P 0 º ac 1-la C/ ka W (R yer PC ) ge L θJA = B H 165 , Pac ºC/ kage W) UA 1-lay er P (R CB, θJA = 228 Packag ºC/W e LH ) 40 60 80 100 120 Temperature (°C) 140 160 180 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 5 A1145 and A1146 Ultrasensitive Two-Wire Chopper