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Part: A3425LKA
Category:
Description: Direction-detecting Hall-effect Sensor
Company: Allegro Micro Systems, Inc.
Datasheet: Download A3425LKA datasheet File size : 116 kB
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3425
DUAL, CHOPPER-STABILIZED, ULTRA-SENSITIVE, BIPOLAR HALL-EFFECT SWITCH
The A3425LK dual Hall-effect switch is an extremely temperature-stable and stress-resistant sensor especially suited for use in digital-encoder systems in the harsh environments of automotive or industrial applications over extended temperature ranges to +150°C. Superior high-temperature performance is made possible through dynamic offset cancellation, which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress. This device also eliminates the major manufacturing hurdles encountered in fine-pitch direction-detection applications, namely maintaining accurate mechanical location between the two active Hall elements. Here, the two Hall elements are photolithographically aligned to better than 1 µm, as contrasted with 100 µm or worse mechanical location tolerance when manufactured discretely. The A3425LK is an ultra-sensitive device optimized for use with highdensity ring magnets. The device includes on a single silicon chip a voltage regulator, two independent chopper-stabilized Hall-voltage generators , two smallsignal amplifiers, two Schmitt triggers, and two short-circuit protected open-collector outputs to sink up to 30 mA each. An on-board regulator permits operation with supply voltages of 3.3 to 26.5 volts. With suitable output pull ups, it can be used directly with bipolar or MOS logic circuits. The A3425LK dual Hall-effect switch is supplied in a 4-pin plastic SIP for operation over a temperature range of -40°C to +150°C. A similar device, with on-chip logic processing specifically for direction detection applications, in a 5-pin SIP, is the A3422LKA.
Data Sheet 27651.20
X
V CC
1
2
3
X
4
OUTPUT2
Dwg. PH-017
OUTPUT1
Pinning is shown viewed from branded side.
PRELIMINARY INFORMATION
(subject to change without notice) January 29, 2001 ABSOLUTE MAXIMUM RATINGS
at TA = +25°C Supply Voltage, VCC ...... 26.5 V Reverse Battery Voltage, VRCC .......... -18 V Zener Current, IZ .... 100 mA Magnetic Flux Density, B .. Unlimited Output Off Voltage, VOUT ........... VCC Output Current, IOUT ...... 30 mA Reverse Output Current, IOUT ........ -50 mA Package Power Dissipation, PD . See Graph Junction Temperature, TJ ...... +170°C Operating Temperature Range, TA, .... -40°C to +150°C Storage Temperature Range, TS ...... -65°C to +170°C
GROUND
SUPPLY
FEATURES
I Two Matched Hall Switches On A Single Substrate
I I I I I I I I
1 mm Sensor-to-Sensor Spacing Superior Temperature Stability Resistant to Physical Stress Output Short-Circuit Protection Operation From Unregulated Supply Reverse Battery Protection Solid-State Reliability Integrated ESD Protection on Outputs and Supply
Always order by complete part number, e.g., A3425LK .
3425 DUAL, CHOPPER-STABILIZED, ULTRA-SENSITIVE, BIPOLAR HALL-EFFECT SWITCH
FUNCTIONAL BLOCK DIAGRAM
1 SUPPLY
REG.
TO ALL SUBCIRCUITS
E1
DYNAMIC OFFSET CANCELLATION
OUTPUT1
LOW-PASS FILTER SAMPLE & HOLD
X
2 CONTROL
CURRENT LIMIT <1
E2
DYNAMIC OFFSET CANCELLATION
OUTPUT2
LOW-PASS FILTER SAMPLE & HOLD
X
3 CONTROL
CURRENT LIMIT <1 GROUND 4
Dwg. FH-020-7
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
1.0
0.8
0.6
0.4
FREE AIR, R JA = 177°C/W
0.2
0 -25
0
25
50
75
100
125
150
175
AMBIENT TEMPERATURE IN °C
Dwg. GH-001-1
2
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 2001 Allegro MicroSystems, Inc.
3425 DUAL, CHOPPER-STABILIZED, ULTRA-SENSITIVE, BIPOLAR HALL-EFFECT SWITCH
ELECTRICAL CHARACTERISTICS over operating temperature range, each switch tested separately (unless otherwise specified).
Limits Characteristic Supply Voltage Range Output Leakage Current Output Saturation Voltage Output Current Limit Chopping Frequency Output Rise Time Output Fall Time Total Supply Current Symbol VC C I OFF V OUT(SAT) IO M fC tr tf I CC RL = 820 , CL = 10 pF RL = 820 , CL = 10 pF Both outputs off, VCC 26.5 V Both outputs on, VCC 26.5 V Reverse Battery Current Zener Voltage Zener Impedance I CC VZ + VD zz + z D VRCC = -18 V ICC = 15 mA, TA = 25°C ICC = 15 mA, TA = 25°C Test Conditions Operating, TJ BOP B > BO P Min. 3.3 30 28 Typ. <1.0 225 340 110 55 3.8 7.5 2.0 33 50 Max. 26.5 10 400 70 8.0 12 15 37 100 Units V µA mV mA kHz ns ns mA mA mA V
NOTES: 1. Supply voltage is limited by allowable package power dissipation as a function of ambient temperature. 2. BOP = operate point (output turns on); BRP = release point (output turns off). 3. Typical Data is at TA = +25°C and VCC = 12 V and is for design information only.
MAGNETIC CHARACTERISTICS over operating supply voltage and temperature ranges, each switch tested separately (unless otherwise specified).
Limits Characteristic Operate Point Symbol B OP1 B OP2 Release Point BR P 1 BRP2 Hysteresis Operate Differential Release Differential Symmetry B hys B OP(dif) B RP(dif) Bsym BOP BRP BOP1 BOP2 BRP1 BRP2 BOP + BRP Test Conditions Min. -30 -30 5.0 Typ. 8.0 11 -11 -8.0 19 -2.0 -3.3 Max. 30 30 35 ±30 ±30 ±40 Units G G G G G G G G
NOTES: 1. As used here, negative flux densities are defined as less than zero (algebraic convention) and -50 G is less than +10 G. 2. Typical Data is at TA = +25°C and VCC = 12 V and is for design information only.
www.allegromicro.com
3
3425 DUAL, CHOPPER-STABILIZED, ULTRA-SENSITIVE, BIPOLAR HALL-EFFECT SWITCH
TYPICAL OPERATING CHARACTERISTICS as a function of temperature
CHANNEL 1 SWITCH POINTS
25 20 15
CHANNEL 2 SWITCH POINTS
25 20 15 VCC = 26.5 V VCC = 18 V VCC = 3.3-5 V
SWITCH POINT IN GAUSS
SWITCH POINT IN GAUSS
10 5 0 -5 -10 -15 -20 -25 -50 OPERATE POINT
VCC = 18-26.5 V VCC = 3.3-5 V
10 OPERATE POINT 5 0 -5 -10 -15 -20 RELEASE POINT VCC = 26.5 V VCC = 5 V VCC = 18 V VCC = 3.3 V
VCC = 5 V VCC = 3.3 V VCC = 18 V VCC = 26.5 V
RELEASE POINT
-25
0
25
50
75
100
125
150
-25 -50
-25
0
25
50
75
100
125
150
AMBIENT TEMPERATURE IN °C
Dwg. GH-026-7
AMBIENT TEMPERATURE IN °C
Dwg. GH-026-8
OUTPUT SATURATION VOLTAGE
300
TOTAL SUPPLY CURRENT
8
VCC = 3.3 V
SATURATION VOLTAGE IN mV
B BOP
VCC = 18 V
VCC = 26.5 V
SUPPLY CURRENT IN mA
VCC = 3.3 V 6
200
4
B BRP VCC = 3.3 V
VCC = 18 V
100 IOUT = 20 mA
2
0 -50
-25
0
25
50
75
100
125
150
0 -50
-25
0
25
50
75
100
125
150
AMBIENT TEMPERATURE IN °C
Dwg. GH-029-5
AMBIENT TEMPERATURE IN °C
Dwg. GH-028-8
4
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
3425 DUAL, CHOPPER-STABILIZED, ULTRA-SENSITIVE, BIPOLAR HALL-EFFECT SWITCH
TYPICAL OPERATING CHARACTERISTICS (cont'd) as a function of supply voltage
OPERATE AND RELEASE DIFFERENTIALS
25 20 15
BOP/BRP DIFFERENTIAL IN GAUSS
10 5 0 -5 -10 -15 -20 -25 -50 BRP VCC = 3.3 V VCC = 5 V VCC = 18 V BOP VCC = 3.3 V VCC = 5-18 V
-25
0
25
50
75
100
125
150
AMBIENT TEMPERATURE IN °C
Dwg. GH-026-9
ACTIVE AREA DEPTH 0.015" 0.38 mm NOM
0.039" 1.00 mm
0.083" 2.11 mm
0.053" 1.34 mm E1 E2
SENSOR LOCATIONS
(±0.005" [0.13 mm] die placement)
BRANDED SURFACE
A
1 2 3 4
Allegro
Dwg. MH-001-4
Although sensor location is accurate to three sigma for a particular design, product improvements may result in small changes to sensor location.
www.allegromicro.com
5
Others parts begin by a3
A3-1 A3-2 A3-3 A3-4
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