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A1205
Continuous-Time Bipolar Switch
Features and Benefits
IdealforapplicationsthatrequirepulsingVCC to conserve power Continuous-timeoperation Fastpower-ontime Lownoise Stableoperationoverfulloperatingtemperaturerange Reversebatteryprotection Solid-statereliability Factory-programmedatend-of-lineforoptimum performance RobustEMCperformance HighESDrating Regulatorstabilitywithoutabypasscapacitor
Description
The Allegro(R) A1205 Hall-effect bipolar switch is a nextgeneration replacement and extension of the popular Allegro A3134 bipolar switch. The A1205 has identical specifications as the A1201 but is recommended for applications that require pulsing VCC to conserve power. For standard applications, where VCC is constant, please refer to the A1201 through A1204 devices. Overall, the A120x family, produced with BiCMOS technology, consists of continuous-time devices that feature fast poweron 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 A120x Hall-effect bipolar switches include the following on a single silicon chip: voltage regulator, Hall-voltage generator,
Packages:
3 pin SOT23W (LH)
3 pin SIP (UA)
Continued on the next page...
Not to scale
Functional Block Diagram
VCC
Regulator
To all subcircuits
VOUT Amp
Gain
Offset
Trim Control
GND
A1205-DS, Rev. 1
A1205
Description (continued) 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.
Continuous-Time Bipolar Switch
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 miniature thin-profile surface-mount package,whilepackageUAisathree-leadultraminiSIPforthroughholemounting.Eachpackageislead(Pb)free,with100%matte tin plated leadframes.
Selection Guide
Part Number A1205ELHLT-T A1205EUA-T A1205LLHLT-T A1205LUA-T Packing* 7-in. reel, 3000 pieces/reel Bulk, 500 pieces/bag 7-in. reel, 3000 pieces/reel Bulk, 500 pieces/bag Mounting 3-pin SOT23W surface mount 3-pin SIP through hole 3-pin SOT23W surface mount 3-pin SIP through hole Ambient, TA -40C to 85C -50 -40C to 150C 50 BRP (Min) BOP (Max)
*Contact Allegro for additional packing options.
Absolute Maximum Ratings
Characteristic Supply Voltage Reverse Supply Voltage Output Off Voltage Reverse Output Voltage Output Current Sink Magnetic Flux Density Operating Ambient Temperature Maximum Junction Temperature Storage Temperature Symbol VCC VRCC VOUT VROUT IOUTSINK
B
Notes
Rating 30 -30 30 -0.5 25 Unlimited
Units V V V V mA G C C C C
TA TJ(max) Tstg
Range E Range L
-40 to 85 -40 to 150 165 -65 to 170
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A1205
Characteristic Electrical Characteristics Supply Voltage1 Output Leakage Current Output On Voltage Power-On Time2 Output Rise Time3 Output Fall Time3 VCC IOUTOFF VOUT(SAT) tPO tr tf ICCON ICCOFF IRCC VZ IZ BOP BRP BHYS Symbol
Continuous-Time Bipolar Switch
Test Conditions Operating, TJ < 165C VOUT = 24 V, B < BRP IOUT = 20 mA, B > BOP Slew rate (dVCC/dt) < 2.5 V/s, B > BOP + 5 G or B < BRP - 5 G VCC = 12 V, RLOAD = 820 , CS = 12 pF VCC = 12 V, RLOAD = 820 , CS = 12 pF B > BOP B < BRP VRCC = -30 V ICC = 30 mA; TA = 25C VZ = 32 V; TA = 25C South pole adjacent to branded face of device North pole adjacent to branded face of device BOP - BRP Min. 3.8 - - - - - - - - 32 - -40 -50 5 Typ. - - 215 - - - 3.8 3.5 - - - 15 -15 30 Max. 24 10 400 4 2 2 7.5 7.5 -10 40 30 50 40 55 Units V A mV s s s mA mA mA V mA
G G G
OPERATING CHARACTERISTICS over full operating voltage and ambient temperature ranges, unless otherwise noted
Supply Current Reverse Battery Current Supply Zener Clamp Voltage Supply Zener Current Magnetic Characteristics4 Operate Point Release Point Hysteresis
1
Maximum voltage must be adjusted for power dissipation and junction temperature, see Power Derating section. 2 For V CC slew rates greater than 2.5 V/s, and TA = 150C, the Power-On Time can reach its maximum value. 3 C =oscilloscope probe capacitance. S 4 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). Reference to the magnetic field polarity is with respect to the beveled face of the device.
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
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A1205
Continuous-Time Bipolar Switch
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic Symbol Test Conditions* Package LH, 1-layer PCB with copper limited to solder pads Package Thermal Resistance RJA 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 *Additional thermal information available on Allegro Web site. Value Units 228 110 165 C/W C/W C/W
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
Power Derating Curve TJ(max) = 165C; ICC = ICC(max)
VCC(max) Package LH, 1-layer PCB (R JA = 228 C/W)
Maximum Allowable VCC (V)
Package UA, 1-layer PCB (R JA = 165 C/W) Package LH, 2-layer PCB (R JA = 110 C/W)
VCC(min)
40 60 80 100 120 140 160 180
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 J C A= 11 B, P 0 ac 1-la C/ ka W (R yer PC ) ge L JA = B H 165 , Pac C/ kage W) UA
1-lay er P (R CB, JA = 228 Packag C/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
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A1205
Continuous-Time Bipolar Switch
Characteristic Data
Supply Current (On) versus Ambient Temperature
8.0 7.0 6.0 8.0 7.0 6.0
Supply Current (On) versus Supply Voltage
ICCON (mA)
5.0 4.0 3.0 2.0 1.0 0 -50 0 50 TA (C) 100 150
ICCON (mA)
VCC (V) 24 3.8
5.0 4.0 3.0 2.0 1.0 0 0 5 10 VCC (V) 15 20 25
TA (C) -40 25 150
Supply Current (Off) versus Ambient Temperature
8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0 -50 0 50 TA (C) 100 150 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0 0
Supply Current (Off) versus Supply Voltage
ICCOFF (mA)
ICCOFF (mA)
VCC (V) 24 3.8
TA (C) -40 25 150
5
10 VCC (V)
15
20
25
Output Voltage (On) versus Ambient Temperature
350 300
ILOAD = 20 mA
Output Voltage (On) versus Supply Voltage
350 300 VCC (V) 24 3.8 250 TA (C) -40 25 150
ILOAD = 20 mA
VOUT(SAT) (mV)
250 200 150 100 50 0 -50 0 50 TA (C) 100 150
VOUT(SAT) (mV)
200 150 100 50 0 0 5 10 VCC (V) 15 20 25
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A1205
Continuous-Time Bipolar Switch
Operate Point versus Ambient Temperature
50 40 30 20 10 0 -10 -20 -30 -40 -50 0 50 TA (C) 100 150 VCC (V) 24 3.8 50 40 30 20 10 0
Operate Point versus Supply Voltage
TA (C) -40 25 150
BOP (G)
BOP (G)
-10 -20 -30 -40 0 5 10 VCC (V) 15 20 25
Release Point versus Ambient Temperature
40 30 20 10 0 -10 -20 -30 -40 -50 -50 0 50 TA (C) 100 150 VCC (V) 24 3.8 40 30 20 10 0
Release Point versus Supply Voltage
TA (C) -40 25 150
BRP (G)
BRP (G)
-10 -20 -30 -40 -50 0 5 10 VCC (V) 15 20 25
Hysteresis versus Ambient Temperature
55 50 45 40 35 30 25 20 15 10 5 -50 0 50 TA (C) 100 150 VCC (V) 24 3.8 55 50 45 40 35 30 25 20 15 10 5 0
Hysteresis versus Supply Voltage
BHYS (G)
BHYS (G)
TA (C) -40 25 150
5
10
VCC (V)
15
20
25
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A1205
Continuous-Time Bipolar Switch
Functional Description
Bipolar Device Switching The devices of the A120X family provide 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 strengthandpolarityoftheswitchpointsofthedevice.(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 magneticfield.) Bipolardevicestypicallybehaveaslatches.Inthismode, magnetic fields of opposite polarity and equivalent strengths areneededtoswitchtheoutput.Whenthemagneticfieldsare removed(B0)thedeviceremainsinthesamestateuntila 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.
Incontrasttolatching,whenadeviceexhibitsunipolarswitching, it only responds to a south magnetic field. The field must be of sufficient strength, > BOP,forthedevicetooperate.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,(morenorththanBRP)isrequiredforoperation,although the result is that VOUTswitcheshigh,asshowninpanelC.When
VS
VCC
RL Sensor Output
A120x
VOUT
GND
(D) (B) (C)
V+ VCC VCC
Switch to High Switch to Low
(A)
V+ VCC
Switch to High Switch to High Switch to Low
V+
Switch to Low
VOUT
VOUT
VOUT(SAT) 0 BRP BRP B- 0 B+ 0 B- 0 BOP BOP
VOUT(SAT) BRP B+ 0 B- 0 BOP
VOUT
VOUT(SAT) B+
BHYS
BHYS
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 120x family, 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
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A1205
Continuous-Time Bipolar Switch
the field is reduced beyond the BOP level, the device switches back to the low state. The typical output behavior of the A120x devices is latching. However, the A120x family 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 A120x family allows clean switching of the output, even in the presence of external mechanical vibration and electrical noise. 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. For more information on Bipolar switches, refer to Application Note 27705, Understanding Bipolar Hall Effect Sensors.
CONTINUOUS-TIME BENEFITS Continuous-time devices, such as the A120x family, offer the fastest available power-on settling time and frequency response. DuetooffsetsgeneratedduringtheICpackagingprocess,continuous-time devices typically require programming after packaging totightenmagneticparameterdistributions.Incontrast,chopper-stabilized 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 choice between continuous-time and chopper-stabilized designs is solely determined by the application. Battery managementisanexamplewherecontinuous-timeisoftenrequired.In these applications, VCC is chopped with a very small duty cycle inordertoconservepower(refertofigure2).Thedutycycle is controlled by the power-on time, tPO, of the device. Because
1
2
3
4
5
VCC
t
VOUT
t
Output Sampled
tPO(max)
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
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A1205
Continuous-Time Bipolar Switch
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 Sensor Using Dynamic Quadrature Offset Cancellation and Technical Paper STP 99-1, Chopper-Stabilized Amplifiers with a Track-and-Hold Signal Demodulator.
ADDITIONAL APPLICATIONS INFORMATION ExtensiveapplicationsinformationforHall-effectsensorsis 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 theAllegroWebsite,www.allegromicro.com.
Pin-out Diagrams
PackageLH
GND
Package UA
3
1 VCC
2 VOUT
1 VCC
2 GND
3 VOUT
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
A1205
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.(Thermaldataisalsoavailableon theAllegroMicroSystemsWebsite.) ThePackageThermalResistance,RJA, is a figure of merit summarizing the ability of the application and the device to dissipate heatfromthejunction(die),throughallpathstotheambientair. ItsprimarycomponentistheEffectiveThermalConductivity, K, of the printed circuit board, including adjacent devices and traces.Radiationfromthediethroughthedevicecase,RJC, is relativelysmallcomponentofRJA. Ambient air temperature, TA, and air motion are significant external factors, damped by overmolding. Theeffectofvaryingpowerlevels(PowerDissipation,PD),can be estimated. The following formulas represent the fundamental relationships used to estimate TJ, at PD. PD = VIN xIIN T = PD x RJA(2) TJ = TA+T (3) (1) Example:ReliabilityforVCC at TA = 150C, package UA, using minimum-K PCB. Observe the worst-case ratings for the device, specifically: RJA= 165C/W,TJ(max)= 165C, 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=15C/165C/W=91mW Finally, invert equation 1 with respect to voltage: VCC(est) = PD(max)/ICC(max) =91mW/7.5mA = 12.1 V The result indicates that, at TA, the application and device can dissipateadequateamountsofheatatvoltagesVCC(est). Compare VCC(est) to VCC(max).IfVCC(est)VCC(max), then reliable operation between VCC(est) and VCC(max) requires enhanced RJA.IfVCC(est)VCC(max), then operation between VCC(est) and VCC(max) is reliable under these conditions.
For example, given common conditions such as: TA= 25C, VCC = 12 V,ICC = 4 mA, and RJA =140C/W,then: PD = VCC x ICC = 12 V x 4mA=48mW T = PD x RJA=48mW x 140C/W=7C TJ = TA + T = 25C + 7C = 32C A worst-case estimate, PD(max), represents the maximum allowablepowerlevel(VCC(max),ICC(max)),withoutexceedingTJ(max), ataselectedRJA and TA.
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A1205
Continuous-Time Bipolar Switch
Package LH, 3-Pin (SOT-23W)
3.00 .118 2.70 .106 0.15 [.006] M C A B 3.04 .120 2.80 .110
A
A 1.49 .059 NOM B 8 0 0.20 .008 0.08 .003
3
B
2.10 .083 1.85 .073 Preliminary dimensions, for reference only Dimensions in millimeters U.S. Customary dimensions (in.) in brackets, for reference only (reference JEDEC TO-236 AB, except case width and terminal tip-to-tip) Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown A Hall element (not to scale) B Active Area Depth 0.28 [.011] 3X 0.10 [.004] C 3X 0.50 .020 0.30 .012 0.20 [.008] M C A B 0.95 .037 1.90 .075
A A NOM
0.96 .038
0.60 .024 0.25 .010
1
2 0.25 .010 SEATING PLANE 1.17 .046 0.75 .030 0.15 .006 0.00 .000 C SEATING PLANE GAUGE PLANE
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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A1205
Continuous-Time Bipolar Switch
Package UA, 3-Pin SIP
.164 4.17 .159 4.04
C D
.091 2.31 NOM
.062 1.57 .058 1.47
D
.122 3.10 .117 2.97
.057 1.45 NOM D
B
.085 2.16 MAX A
.031 0.79 REF
Dimensions in inches Metric dimensions (mm) in brackets, for reference only A Dambar removal protrusion (6X)
B Ejector mark on opposite side C Active Area Depth .0195 [0.50] NOM D Hall element (not to scale)
.640 16.26 .600 15.24
.017 0.44 .014 0.35
1 .019 0.48 .014 0.36
2
3
.050 1.27 NOM
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 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. 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. Copyright (c)2006, Allegro MicroSystems, Inc.
For the latest version of this document, go to our website at: www.allegromicro.com
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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