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3197
PROTECTED, HIGH-TEMPERATURE, OPEN-COLLECTOR HALL-EFFECT LATCH
These open-collector Hall-effect latches are capable of sensing magnetic fields while using an unprotected power supply. The A3197LLT and A3197LU can provide position and speed information by providing a digital output for magnetic fields that exceed their predefined switch points. These devices operate down to zero speed and have switch points that are designed to be extremely stable over a wide operating temperature and voltage range. The latching characteristics make them ideal for use in pulse counting applications when used with a multi-pole ring magnet. Thermal and output short-circuit protection allow an increased wiring harness fault tolerance. The temperature compensated switch points, the wide operating voltage range, and the integrated protection make these devices ideal for use in automotive applications such as transmission speed sensors and integrated wheel bearing speed sensors.
3
Data Sheet 27609.10A
X
PTCT
V
CC
1
2
Dwg. PH-003-2
Each monolithic device contains an integrated Hall-effect transducer, a temperature-compensated comparator, a voltage regulator, and a buffered 35 mA output sink stage. Supply protection is made possible by the integration of overvoltage and undervoltage shutdown circuitry that monitor supply fault conditions and shut down the IC. Noise shutdown circuitry (patent applied for) prevents the propagation of supply transients to the logic load. Output protection circuitry includes a current limit loop that limits the maximum output sink current, and thermal protection circuitry that shuts down the device during an over-heating condition such as with a shorted load. The A3197LLT and A3197LU are rated for operation over an extended temperature range of -40C to +150C. They are supplied in a three-lead SIP (suffix `U') or a surface-mount SOT-89 (suffix `LT').
GROUND
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC (100 ms) ................................... 115 V* (continuous) ............................... 28 V* Reverse Battery Voltage, VRCC (100 ms) ................................... -100 V (continuous) ............................... -35 V Magnetic Flux Density, B .......... Unlimited Output OFF Voltage, VOUT ................. 26 V Reverse Output Voltage VOUT ......... -0.5 V Continuous Output Current, IOUT .......................................... 35 mA* Reverse Output Current, IOUT ........................................ -100 mA Package Power Dissipation, PD ....................................... See Graph Junction Temperature, TJ ................. 170C Operating Temperature Range, TA .......................................... -40C to +150C Storage Temperature, TS .................. 170C
*Fault condition, internal overvoltage shutdown above 28 V; output current limited above 35 mA.
OUTPUT
SUPPLY
FEATURES
I I I I I I I I I I Internal Protection For Automotive (ISO/DIN) Transients Operation From Unregulated Supply Reverse Battery Protection Undervoltage Lockout Supply Noise-Suppression Circuitry Output Short-Circuit Protection Output Zener Clamp Thermal Protection Symmetrical Latching Switch Points Operable with Multipole Ring Magnets
Always order by complete part number, e.g., A3197LU .
3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
FUNCTIONAL BLOCK DIAGRAM
1 VCC
OVERVOLT. LOCKOUT REG.
POWER UP & TRANSIENT PROTECTION
3
OUTPUT
CONTROL
X
THERMAL SHUTDOWN CURRENT LIMIT <1
2
Dwg. FH-012A
GROUND
800
ALLOWABLE PACKAGE POWER DISSIPATION IN mW
700 600 500 400 300 200 100 0 "LT" PACKAGE RJA = 258C/W "U" PACKAGE RJA = 183C/W
NOTE - Permitted duty cycle will be less than 100% at maximum ambient temperature with high supply voltages, i.e., TA 140C, VCC 12 V, and the "LT" package. The thermal shutdown circuitry does not protect the device from these stresses (see Internal Protective Features).
20
40
60 100 140 80 120 AMBIENT TEMPERATURE IN C
160
180
Dwg. GH-054A
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright (c) 1995, 1999, Allegro MicroSystems, Inc.
3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
ELECTRICAL CHARACTERISTICS over operating voltage and temperature range (unless otherwise specified).
Limits Characteristic Supply Voltage Overvoltage Shutdown* Undervoltage Shutdown* Output Voltage, On Output Leakage Current Output Clamp Voltage Output Current Limit Supply Current Symbol VCC VCC(OV) VCC(UV) VOUT(SAT) IOFF VOUT(CLMP) IOUTMAX ICC Test Conditions Operating (but VCC x ICC vs TA limited) B > BOP B > BOP B > BOP, IOUT = 30 mA, VCC = 16 V VOUT = 26 V B < BRP, VCC = 115 V*, IOUT = 0 B > BOP, VOUT = 12 V B < BRP, VCC = 24 V, IOUT = 0 B > BOP, VCC = 24 V, IOUT = 20 mA VCC = +115 V* VRCC = -35 V* VRCC = -100 V* CL = 20 pF, RL = 330 , VBB = 12 V CL = 20 pF, RL = 330 , VBB = 12 V Min. VCC(UV) 28 3.7 -- -- 28 35 -- -- -- -- -- -- -- 165 "LT" Package "U" Package -- -- Typ. 12 -- -- 0.2 -- 32 50 5.2 7.8 8.0 -0.5 -2.0 0.05 0.30 -- 258 183 Max. 26 55 4.5 0.5 5.0 40 70 9.0 12 17 -5.0 -10 2.0 5.0 190 -- -- Units V V V V A V mA mA mA mA mA mA s s C C/W C/W
Reverse Battery Current* Output Rise Time Output Fall Time Thermal Shutdown Temp.* Package Thermal Resist.
IRCC tr tf TJ RJA
MAGNETIC CHARACTERISTICS over operating voltage range (unless otherwise specified).
Limits Characteristic Operate Point Symbol BOP Test Conditions TA = -40C TA = +25C TA = +150C TA = -40C TA = +25C TA = +150C TA = -40C TA = +25C TA = +150C Min. 60 50 40 -200 -160 -150 150 130 110 Typ. 130 110 105 -140 -120 -100 270 230 205 Max. 200 160 150 -60 -50 -40 -- -- -- Units G G G G G G G G G
Release Point
BRP
Hysteresis (BOP - BRP)
Bhys
NOTES: BOP = magnetic operate point (output turns ON); BRP = magnetic release point (output turns OFF). As used here, negative flux densities are defined as less than zero (algebraic convention). Typical values are at TA = +25C and VCC = 12 V (unless otherwise specified). * Fault condition. Device is shut down and operation is not possible.
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3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
TYPICAL OPERATING CHARACTERISTICS
Switch Points
200
Output Saturation Voltage
500
OPERATE POINT
400
SATURATION VOLTAGE IN mV
VCC = 12 V
B BOP
100
SWITCH POINTS IN GAUSS
300
0
VCC = 5 V-24 V
200
IOUT = 30 mA
-100 RELEASE POINT
100 I OUT = 5 mA
-200 -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-052-2
AMBIENT TEMPERATURE IN C
Dwg. GH-040-3
Supply Current
8.0 B B OP
SUPPLY CURRENT IN mA
VCC = 24 V
7.0
V CC= 5 V
6.0
VCC = 24 V 5.0 B B RP VCC = 5 V 4.0 -50 -25 0 25 50 75 100 125 150
AMBIENT TEMPERATURE IN C
Dwg. GH-028-3
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
OPERATION
In operation, the output transistor is OFF until the strength of the magnetic field perpendicular to the surface of the chip exceeds the threshold or operate point (BOP). When the field strength exceeds BOP, the output transistor switches ON (a logic low) and is capable of sinking 35 mA of current. The output transistor switches OFF (a logic high) when magnetic field reversal results in a magnetic flux density below the OFF threshold (BRP). This is illustrated in the transfer characteristics graph. Note that the device latches; that is, a south pole of sufficient strength will turn the device ON. Removal of the south pole will leave the device ON. The presence of a north pole of sufficient strength is required to turn the device OFF. The switch points increase in sensitivity with increasing temperature to compensate for the typical ferrite magnet temperature characteristic. The simplest form of magnet that will operate these devices is a ring magnet. Other methods of operation are possible.
TEST CIRCUIT AND TYPICAL APPLICATION
VCC(UV) TO 26 V WITH TRANSIENTS VCC
1
REGULATED < 26 V VBB
RL
3
TO P
CBYPASS
X
CL
2
Dwg. EH-006A
26 V MAX
VBB
OUTPUT VOLTAGE IN VOLTS
B RP
B OP
VOUT(SAT)
0 -B 0 FLUX DENSITY +B
Dwg. GH-034-2A
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3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
Power Up Reset. These devices are designed to power up with the output OFF without regard to any magnetic field applied. The output will remain OFF until the flux is reduced to below BRP (S-N transition) and then BOP is exceeded, depending on the turn-on state of the internal latches.
+B 0 -B VCC 0 FIRST BOP AFTER POWER UP VOUT VOUT(SAT)
Dwg. WH-006
BOP BRP
Power Supply Transients (Noise); Overvoltage and Undervoltage Lockout. Even in protected devices, positive and negative power supply transients that would not normally cause physical damage can cause logic errors in control systems. The A3197LT and A3197LU include noise suppression features to prevent this. In a typical application, where the output is externally pulled up to a regulated voltage <28 V, the effects of power supply transients on the device output are suppressed by turning the output driver OFF during the first undervoltage, VCC(UV), (or negative) condition, or first overvoltage (positive) condition, VCC(OV), and maintaining a power up reset mode until normal power is restored. Note that after the initial transient, the output does not change logic state during subsequent power supply noise pulses. An external 0.1 F to 0.5 F capacitor, with good high-frequency characteristics, should be connected between terminals 1 and 2 to bypass high-voltage noise and reduce EMI susceptibility.
BOP 0 BRP
VCC 0 FIRST BOP AFTER TRANSIENT(S)
VOUT CLASSICAL OUTPUT RESPONSE
VOUT A3197- OUTPUT RESPONSE
Dwg. WH-007-2A
BOP 0 BRP
VCC 0 FIRST BOP AFTER TRANSIENT(S)
VOUT CLASSICAL OUTPUT RESPONSE
VOUT A3197- OUTPUT RESPONSE
Dwg. WH-007-1A
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
INTERNAL PROTECTIVE FEATURES
ISO Pulse No. 1 2 3a 3b 4 5 Test Inductive Turn Off (Negative) Inductive Turn Off (Positive) Capacitive/Inductive Coupling (Neg) Capacitive/Inductive Coupling (Pos) Reverse Battery Load Dump (ISO) (DIN) 6 7 Ignition Coil Disconnect EXTERNAL PROTECTION REQ'D Field Decay (Negative) Test Conditions (over operating temperature range) VS = -100 V, RS = 10 , tr = 1 s, td = 2 ms VS = 100 V, RS = 10 , tr = 1 s, td = 50 s VS = -150 V, RS = 50 , tr = 50 ns, td = 100 ns VS = 100 V, RS = 50 , tr = 50 ns, td = 100 ns VS = -14 V, td = 20 s VS = 86.5 V, RS = 0.5 , tr = 5 ms, td = 400 ms VS = 120 V, RS = 0.5 , tr = 100 ns, td = 400 ms VS = -300 V, RS = 30 , tr = 60 s, td = 300 s VS = -80 V, RS = 10 , tr = 5 ms, td = 100 ms
0.9 V S
VS
0.1 V 12 V 0
S
tr td
Dwg. WH-008
Power supply voltage transients, or device output short circuits, may be caused by faulty connectors, crimped wiring harnesses, or service errors. To prevent catastrophic failure, internal protection against overvoltage, reverse voltage, output overloads, and thermal stress have been incorporated to meet the automotive 12 volt system protection requirements of ISO DP7637/1 and DIN 40839-1. A seriesblocking diode or current-limiting resistor is required in order to survive pulse number six.
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3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
Output Overloads. Current through the output transistor is sensed with a low-value on-chip aluminum resistor. The voltage drop across this resistor is fed back to control the base drive of the output stage. This feedback prevents the output transistor from exceeding its maximum current density rating by limiting the output current to between 35 mA and 70 mA. Under short-circuit conditions, the device will dissipate an increased amount of power (PD = VOUT x ILIMIT) and the output transistor will be thermally stressed. Thermal Stress. When thermal stresses (either internal or external) cause the junction temperature to exceed +165C, thermal shutdown of the output transistor is activated. The thermal shutdown circuitry only provides protection against thermal stresses caused by increased power dissipation of the output transistor. Overvoltage. The device protects itself against highvoltage transients by shutting OFF all supply-referenced active components, reducing the supply current, and minimizing device power dissipation. Overvoltage shutdown can occur anywhere between 28 V and 55 V and device operation above 28 V cannot be recommended. Under a sustained overvoltage, the device may be required to dissipate an increased amount of power (PD = VCC x ICC) and the device may be thermally stressed (see above). Output Voltage. The output is clamped with an on-chip Zener diode to limit the maximum output voltage that can occur during overvoltage faults or when switching an inductive load. When any fault condition is removed, the device returns to normal operating mode.
CRITERIA FOR DEVICE QUALIFICATION
All Allegro sensors are subjected to stringent qualification requirements prior to being released to production. To become qualified, except for the destructive ESD tests, no failures are permitted.
Qualification Test Biased Humidity High-Temperature Operating Life Surge Operating Life Pressure Cooker, Unbiased Storage Life Temperature Cycle ESD Human Body Model ESD Machine Model
Test Method and Test Conditions JESD22-A101 TA = 85C, RH = 85% JESD22-A108 TA = 150C, TJ = 165C JESD22-A108 TA = 175C, TJ = 190C JESD22-A102, Method C MIL-STD-883, Method 1008 TA = 170C MIL-STD-883, Method 1010 MIL-STD-883, Method 3015
No. of Lots 3 3 1 3 1 3 1 1
Test Length 1200 hrs 1200 hrs 504 hrs 96 hrs 1200 hrs 1000 cycles Pre/Post Reading Pre/Post Reading
Samples Per Lot 116 116 116 77 77 153 3 per test 3 per test
Comments Device biased for minimum power
Test to failure HBM > 16 kV Test to failure MM > 800 V
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
SENSOR LOCATIONS
(0.005" [0.13 mm] die placement)
APPLICATIONS INFORMATION
The A3197LLT and A3197LU latches have been optimized for use in automotive ring magnet sensing applications. Such applications include transmission speed sensors, motor position encoders, and wheel bearing speed sensors. Special care has been taken to optimize the operation of these devices in automotive subsystems that require ISO DP9637 protection but NOT operation. Undervoltage lockout is included to prevent propagation of false logic pulses during low battery, cold-start conditions. Noise suppression is included to prevent false switching of the device when subjected to ISO transients. Short-circuit protection is included to prevent damage caused by pinched wiring harnesses. A typical application consists of a ferrite ring magnet located on a rotating shaft. Typically, this shaft is attached to the transmission, the sensor is mounted on a board, with care being taken to keep a tight tolerance on the air gap between the package face and the magnet. The device will provide a change in digital state at the transition of every magnetic pole and, thus, give an indication of the transmission speed. The high magnetic hysteresis allows the device to be immune to vibration of the magnet shaft and relatively good duty cycles can be obtained. Hall effect applications information is available in the "Hall-Effect IC Applications Guide", which can be found in the Allegro MicroSystems Electronic Data Book, AMS-702, or Application Note 2770, or at
SUFFIX "LT"
ACTIVE AREA DEPTH 0.030" 0.76 mm
NOM
0.092" 2.35 mm
0.051" 1.30 mm
A
1 2 3
Dwg. MH-008-5A
SUFFIX "U"
ACTIVE AREA DEPTH 0.015" 0.38 mm
NOM
0.094" 2.40 mm
0.073" 1.85 mm
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A
BRANDED SURFACE 1 2 3
Dwg. MH-002-12A
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3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
A3197ELT and A3197LLT
Dimensions in Inches (for reference only)
0.181 0.173 0.072 0.064 0.167 0.155 0.102 0.090
0.063 0.055
0.0173 0.0138
1
2
3
0.090 0.084
0.047 0.035 0.059
BSC
0.0189 0.0142 0.0221 0.0173 0.118
BSC
Dwg. MA-009-3A in
Dimensions in Millimeters (controlling dimensions)
4.60 4.40 1.83 1.62 4.25 3.94 2.60 2.29
1.60 1.40
0.44 0.35
1
2
3
2.29 2.13
1.20 0.89 1.50
BSC
0.48 0.36 0.56 0.44 3.00
BSC
Dwg. MA-009-3A mm
NOTE -- Exact body and lead configuration at vendor's option within limits shown.
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
A3197EU and A3197LU
Dimensions in Inches (controlling dimensions) Dimensions in Millimeters (for reference only)
0.183 0.178 0.063 0.059
4.65 4.52 1.60 1.50
0.181 0.176 45 0.086
MAX
4.60 4.47 45 2.18
MAX
1
2
3
0.018
1
2
3
0.46
0.600 0.560 0.0189 0.0142
SEE NOTE
0.0173 0.0138
15.24 14.23 0.48 0.36
SEE NOTE
0.44 0.35
0.050 0.100
Dwg. MH-003E in
1.27 2.54
Dwg. MH-003E mm
NOTES: 1. Tolerances on package height and width represent allowable mold offsets. Dimensions given are measured at the widest point (parting line). 2. Exact body and lead configuration at vendor's option within limits shown. 3. Height does not include mold gate flash. 4. Recommended minimum PWB hole diameter to clear transition area is 0.035" (0.89 mm). 5. Where no tolerance is specified, dimension is nominal.
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3197 PROTECTED, HIGH-TEMP., OPEN-COLLECTOR HALL-EFFECT LATCH
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. Allegro products are not authorized for use as critical components in life-support appliances, devices, or systems without express written approval. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties that may result from its use.
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000

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