A1201 Continuous-Time Bipolar Switch Features and Benefits Description ▪ Continuous-time operation ▫ Fast power-on time ▫ Low noise ▪ Stable operation over full operating temperature range ▪ Reverse battery protection ▪ Solid-state reliability ▪ Factory-programmed at end-of-line for optimum performance ▪ Robust EMC performance ▪ High ESD rating ▪ Regulator stability without a bypass capacitor The Allegro® A1201 Hall-effect bipolar switch is a nextgeneration replacement and extension of the popular Allegro A3134 bipolar switch. Overall, the A1201, produced with BiCMOS technology, is a continuous-time device that features fast power-on time and low-noise operation. Device programming is performed after packaging, to ensure increased switchpoint accuracy by eliminating offsets that can be induced by package stress. Unique Hall element geometries and lowoffset amplifiers help to minimize noise and to reduce the residual offset voltage normally caused by device overmolding, temperature excursions, and thermal stress. The A1201 Hall-effect bipolar switch includes the following on a single silicon chip: voltage regulator, Hall-voltage generator, small-signal amplifier, Schmitt trigger, and NMOS output transistor. The integrated voltage regulator permits operation from 3.8 to 24 V. The extensive on-board protection circuitry makes possible a ±30 V absolute maximum voltage rating for superior protection in automotive and motor commutation applications, without adding external components. The device is a member of the A1201 product family which has identical electrical characteristics throughout, but provides a range of magnetic switchpoints. Packages: 3 pin SOT23W (suffix LH), and 3 pin SIP (suffix UA) Continued on the next page… Not to scale Functional Block Diagram VCC To all subcircuits Regulator VOUT Amp Gain Offset Trim Control GND A1201-DS, Rev. 14 A1201 Continuous-Time Bipolar Switch Description (continued) The small geometries of the BiCMOS process allow these devices to be provided in ultrasmall packages. The package styles available provide magnetically optimized solutions for most applications. Package LH is a SOT23W, a miniature low-profile surface-mount package, while package UA is a three-lead ultramini SIP for throughhole mounting. Each package is lead (Pb) free, with 100% matte tin plated leadframes. Selection Guide Part Number Packing1 Mounting Ambient, TA A1201ELHLT-T2 7-in. reel, 3000 pieces/reel 3-pin SOT23W surface mount –40ºC to 85ºC Bulk, 500 pieces/bag 3-pin SIP through hole 7-in. reel, 3000 pieces/reel 3-pin SOT23W surface mount Bulk, 500 pieces/bag 3-pin SIP through hole A1201EUA-T2 A1201LLHLT-T2 A1201LUA-T2 BRP (Min) BOP (Max) –50 50 –40ºC to 150ºC 1Contact Allegro for additional packing options. 2Variant is obsolete. Absolute Maximum Ratings Rating Units Supply Voltage Characteristic VCC 30 V Reverse Supply Voltage VRCC –30 V Output Off Voltage VOUT 30 V VROUT –0.5 V IOUTSINK 25 mA Reverse Output Voltage Output Current Sink Magnetic Flux Density Symbol Notes Unlimited G Range E –40 to 85 ºC Range L –40 to 150 ºC B Operating Ambient Temperature TA Maximum Junction Temperature TJ(max) 165 ºC Tstg –65 to 170 ºC Storage Temperature Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 2 A1201 Continuous-Time Bipolar Switch Pin-out Diagrams Package UA GND Package LH 2 3 VOUT VOUT 1 GND 2 VCC 1 VCC 3 Terminal List Name VCC VOUT GND Description Connects power supply to chip Output from circuit Ground Number Package LH Package UA 1 1 2 3 3 2 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 3 A1201 Continuous-Time Bipolar Switch OPERATING CHARACTERISTICS over full operating voltage and ambient temperature ranges, unless otherwise noted Characteristic Symbol Test Conditions Min. Typ. Max. Units Electrical Characteristics Supply Voltage1 Output Leakage Current Output On Voltage Power-On Time2 Output Rise Time3 Output Fall Time3 Supply Current Reverse Battery Current VCC Operating, TJ < 165°C 3.8 – 24 V IOUTOFF VOUT = 24 V, B < BRP – – 10 μA VOUT(SAT) IOUT = 20 mA, B > BOP – 215 400 mV Slew rate (dVCC/dt) < 2.5 V/μs, B > BOP(max) + 5 G or B < BRP(min) – 5 G – – 4 μs tr VCC = 12 V, RLOAD = 820 Ω, CS = 12 pF – – 2 μs tf tPO VCC = 12 V, RLOAD = 820 Ω, CS = 12 pF – – 2 μs ICCON B > BOP – 3.8 7.5 mA ICCOFF B < BRP – 3.5 7.5 mA VRCC = –30 V – – –10 mA IRCC Supply Zener Clamp Voltage VZ ICC = 30 mA; TA = 25°C 32 – – V Supply Zener Current4 IZ VZ = 32 V; TA = 25°C – – 30 mA Magnetic Characteristics5 Operate Point BOP A1201 South pole adjacent to branded face of device –40 15 50 G Release Point BRP A1201 North pole adjacent to branded face of device –50 –15 40 G Hysteresis BHYS A1201 BOP – BRP 5 30 55 G 1 Maximum voltage must be adjusted for power dissipation and junction temperature, see Power Derating section. 2 For V CC slew rates greater than 250 V/μs, and TA = 150°C, the Power-On Time can reach its maximum value. 3 C =oscilloscope probe capacitance. S 4 Maximum current limit is equal to the maximum I CC(max) + 22 mA. 5 Magnetic flux density, B, is indicated as a negative value for north-polarity magnetic fields, and as a positive value for south-polarity magnetic fields. This so-called algebraic convention supports arithmetic comparison of north and south polarity values, where the relative strength of the field is indicated by the absolute value of B, and the sign indicates the polarity of the field (for example, a –100 G field and a 100 G field have equivalent strength, but opposite polarity). DEVICE QUALIFICATION PROGRAM Contact Allegro for information. EMC (Electromagnetic Compatibility) REQUIREMENTS Contact Allegro for information. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 4 A1201 Continuous-Time Bipolar Switch THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information Characteristic Symbol Test Conditions RθJA Maximum Allowable VCC (V) Package Thermal Resistance Value Units 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 Power Derating Curve TJ(max) = 165ºC; ICC = ICC(max) 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 VCC(max) Package LH, 2-layer PCB (RQJA = 110 ºC/W) Package UA, 1-layer PCB (RQJA = 165 ºC/W) Package LH, 1-layer PCB (RQJA = 228 ºC/W) VCC(min) 20 40 60 80 100 120 140 160 180 Power Dissipation, PD (mW) 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 Pa (R cka ge QJ A = L 11 H, 2 0 º -la Pac C/ ye W (R kage ) r PC UA QJA = B , 165 1-la ºC/ yer W) PC B Pac k (R age LH , QJA = 228 1-laye ºC/W r PC B ) 20 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 A1201 Continuous-Time Bipolar Switch Characteristic Data Supply Current (On) versus Ambient Temperature Supply Current (On) versus Supply Voltage (A1201) (A1201) 8.0 7.0 7.0 ICCON (mA) 6.0 VCC (V) 5.0 24 3.8 4.0 3.0 ICCON (mA) 8.0 6.0 TA (°C) 5.0 –40 25 150 4.0 3.0 2.0 2.0 1.0 1.0 0 0 –50 0 50 TA (°C) 100 150 0 5 10 Supply Current (Off) versus Ambient Temperature 25 (A1201) 8.0 7.0 7.0 VCC (V) 5.0 24 3.8 4.0 3.0 ICCOFF (mA) 8.0 6.0 ICCOFF (mA) 20 Supply Current (Off) versus Supply Voltage (A1201) 6.0 TA (°C) 5.0 –40 25 150 4.0 3.0 2.0 2.0 1.0 1.0 0 0 –50 0 50 TA (°C) 100 0 150 10 15 20 25 Output Voltage (On) versus Supply Voltage (A1201) 400 5 VCC (V) Output Voltage (On) versus Ambient Temperature (A1201) 400 350 350 300 300 250 VCC (V) 200 24 3.8 150 100 50 VOUT(SAT) (mV) VOUT(SAT) (mV) 15 VCC (V) TA (°C) 250 –40 25 150 200 150 100 50 0 0 –50 0 50 TA (°C) 100 150 0 5 10 15 20 25 VCC (V) Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 6 A1201 Continuous-Time Bipolar Switch Operate Point versus Ambient Temperature Operate Point versus Supply Voltage (A1201) 50 40 40 30 30 20 20 VCC (V) 10 24 12 3.8 0 -10 BOP (G) BOP (G) (A1201) 50 –40 25 150 0 -10 -20 -20 -30 -30 -40 TA (°C) 10 -40 -50 0 50 TA (°C) 100 150 0 20 25 (A1201) 40 30 30 20 20 10 24 12 3.8 -10 -20 BRP (G) VCC (V) 0 –40 25 150 -10 -20 -30 -30 -40 -40 -50 TA (°C) 0 -50 -50 0 50 100 150 0 5 10 15 20 TA (°C) VCC (V) Hysteresis versus Ambient Temperature Hysteresis versus Supply Voltage (A1201) 55 (A1201) 55 50 50 45 45 40 VCC (V) 35 24 12 3.8 30 25 40 TA (°C) 35 –40 25 150 30 25 20 20 15 15 10 10 5 25 BHYS (G) BRP (G) 15 Release Point versus Supply Voltage (A1201) 10 BHYS (G) 10 VCC (V) Release Point versus Ambient Temperature 40 5 5 -50 0 50 TA (°C) 100 150 0 5 10 15 20 25 VCC (V) Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 7 A1201 Continuous-Time Bipolar Switch Functional Description Bipolar Device Switching The A1201 provides highly sensitive switching for applications using magnetic fields of alternating polarities, such as ring magnets. There are three switching modes for bipolar devices, referred to as latch, unipolar switch, and negative switch. Mode is determined by the switchpoint characteristics of the individual device. The characteristic hysteresis, BHYS , of the device, is the difference in the relative magnetic strength and polarity of the switchpoints of the device. (Note that, in the following descriptions, a negative magnetic value indicates a north polarity field, and a positive magnetic value indicates a south polarity field. For a given value of magnetic strength, BX , the values –BX and BX indicate two fields of equal strength, but opposite polarity. B = 0 indicates the absence of a magnetic field.) In contrast to latching, when a device exhibits unipolar switching, it only responds to a south magnetic field. The field must be of sufficient strength, > BOP , for the device to operate. When the field is reduced beyond the BRP level, the device switches back to the high state, as shown in panel B of figure 1. Devices exhibiting negative switch behavior operate in a similar but opposite manner. A north polarity field of sufficient strength, > BRP , (more north than BRP) is required for operation, although the result is that VOUT switches high, as shown in panel C. When VS VCC Bipolar devices typically behave as latches. In this mode, magnetic fields of opposite polarity and equivalent strengths are needed to switch the output. When the magnetic fields are removed (B 0) the device remains in the same state until a magnetic field of the opposite polarity and of sufficient strength causes it to switch. The hysteresis of latch mode behavior is shown in panel A of figure 1. A1201 RL Output VOUT GND (D) (B) BRP BHYS VCC VOUT Switch to High Switch to High VOUT VOUT VOUT(SAT) B– 0 V+ B+ 0 VOUT(SAT) B– BOP B+ 0 BOP BHYS BOP 0 VCC Switch to Low VOUT(SAT) B– V+ Switch to Low 0 Switch to Low Switch to High VCC BRP V+ (C) BRP (A) 0 B+ BHYS Figure 1. Bipolar Device Output Switching Modes. These behaviors can be exhibited when using a circuit such as that shown in panel D. Panel A displays the hysteresis when a device exhibits latch mode (note that the BHYS band incorporates B= 0), panel B shows unipolar switch behavior (the BHYS band is more positive than B = 0), and panel C shows negative switch behavior (the BHYS band is more negative than B = 0). Bipolar devices, such as the A1201, can operate in any of the three modes. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 8 A1201 Continuous-Time Bipolar Switch the field is reduced beyond the BOP level, the device switches back to the low state. Bipolar devices adopt an indeterminate output state when powered-on in the absence of a magnetic field or in a field that lies within the hysteresis band of the device. The typical output behavior of the A1201 device is latching. That is, switching to the low state when the magnetic field at the Hall element exceeds the operate point threshold, BOP . At this point, the output voltage is VOUT(SAT). When the magnetic field is reduced to below the release point threshold, BRP , the device output, VOUT , goes high. The values of the magnetic parameters are specified in the Magnetic Characteristics table, on page 3. Note that, as shown in figure 1, these switchpoints can lie in either north or south polarity ranges. For more information on Bipolar switches, refer to Application Note 27705, Understanding Bipolar Hall Effect Sensor ICs. CONTINUOUS-TIME BENEFITS Continuous-time devices, such as the A1201, offer the fastest available power-on settling time and frequency response. Due to offsets generated during the IC packaging process, continuoustime devices typically require programming after packaging to tighten magnetic parameter distributions. In contrast, chopperstabilized switches employ an offset cancellation technique on the chip that eliminates these offsets without the need for after-packaging programming. The tradeoff is a longer settling time and reduced frequency response as a result of the chopperstabilization offset cancellation algorithm. The A1201 is designed to attain a small hysteresis, and thereby provide more sensitive switching. Although this means that true latching behavior cannot be guaranteed in all cases, proper switching can be ensured by use of both south and north magnetic fields, as in a ring magnet. The hysteresis of the A1201 allows clean switching of the output, even in the presence of external mechanical vibration and electrical noise. 1 2 3 4 5 VCC t VOUT t tPO(max) Output Sampled Figure 2. Continuous-Time Application, B < BRP.. This figure illustrates the use of a quick cycle for chopping VCC in order to conserve battery power. Position 1, power is applied to the device. Position 2, the output assumes the correct state at a time prior to the maximum Power-On Time, tPO(max). The case shown is where the correct output state is HIGH . Position 3, tPO(max) has elapsed. The device output is valid. Position 4, after the output is valid, a control unit reads the output. Position 5, power is removed from the device. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 9 A1201 The choice between continuous-time and chopper-stabilized designs is solely determined by the application. Battery management is an example where continuous-time is often required. In these applications, VCC is chopped with a very small duty cycle in order to conserve power (refer to figure 4). The duty cycle is controlled by the power-on time, tPO, of the device. Because continuous-time devices have the shorter power-on time, they are the clear choice for such applications. For more information on the chopper stabilization technique, refer to Technical Paper STP 97-10, Monolithic Magnetic Hall Sensing Using Dynamic Quadrature Offset Cancellation and Technical Paper STP 99-1, Chopper-Stabilized Amplifiers with a Track-and-Hold Signal Demodulator. Continuous-Time Bipolar Switch ADDITIONAL APPLICATIONS INFORMATION Extensive applications information for Hall-effect devices is available in: • Hall-Effect IC Applications Guide, Application Note 27701 • Hall-Effect Devices: Gluing, Potting, Encapsulating, Lead Welding and Lead Forming, Application Note 27703.1 • Soldering Methods for Allegro’s Products – SMT and ThroughHole, Application Note 26009 All are provided in Allegro Electronic Data Book, AMS-702, and the Allegro Web site, www.allegromicro.com. 10 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1201 Continuous-Time Bipolar Switch Power Derating Power Derating The device must be operated below the maximum junction temperature of the device, TJ(max). Under certain combinations 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 TJ. (Thermal data is also available on the Allegro MicroSystems Web site.) The Package Thermal Resistance, RJA, is a figure of merit summarizing 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, RJC, 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 TJ, at PD. PD = VIN × IIN (1) T = PD × RJA (2) TJ = TA + ΔT Example: Reliability for VCC at TA = 150°C, package UA, using minimum-K 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) = 7.5 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 ÷ 7.5 mA = 12.1 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 conditions. (3) For example, given common conditions such as: TA= 25°C, VCC = 12 V, ICC = 4 mA, and RJA = 140 °C/W, then: PD = VCC × ICC = 12 V × 4 mA = 48 mW T = PD × RJA = 48 mW × 140 °C/W = 7°C TJ = TA + T = 25°C + 7°C = 32°C A worst-case estimate, PD(max), represents the maximum allowable power level (VCC(max), ICC(max)), without exceeding TJ(max), at a selected RJA and TA. 11 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1201 Continuous-Time Bipolar Switch Package LH, 3-Pin (SOT-23W) +0.12 2.98 –0.08 1.49 D 4°±4° 3 A +0.020 0.180–0.053 0.96 D +0.10 2.90 –0.20 +0.19 1.91 –0.06 2.40 0.70 D 0.25 MIN 1.00 2 1 0.55 REF 0.25 BSC 0.95 Seating Plane Gauge Plane 8X 10° REF B PCB Layout Reference View Branded Face 1.00 ±0.13 +0.10 0.05 –0.05 0.95 BSC 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 A Active Area Depth, 0.28 mm REF 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 C Branding scale and appearance at supplier discretion D Hall element, not to scale NNT 1 C Standard Branding Reference View N = Last two digits of device part number T = Temperature code 12 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com A1201 Continuous-Time Bipolar Switch Package UA, 3-Pin SIP +0.08 4.09 –0.05 45° B C E 2.04 1.52 ±0.05 1.44 E Mold Ejector Pin Indent +0.08 3.02 –0.05 E Branded Face 45° 1 2.16 MAX D Standard Branding Reference View = Supplier emblem N = Last two digits of device part number T = Temperature code 0.79 REF A 0.51 REF NNT 1 2 3 +0.03 0.41 –0.06 15.75 ±0.51 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 A Dambar removal protrusion (6X) B Gate burr area C Active Area Depth, 0.50 mm REF +0.05 0.43 –0.07 D Branding scale and appearance at supplier discretion E Hall element, not to scale 1.27 NOM Copyright ©2005-2009, Allegro MicroSystems, Inc.Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit 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 13 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com