A3197: Protected, High-Temp., Open-Collector Hall-Effect Latch

Data Sheet
27609.10b
3197
PROTECTED, HIGH-TEMPERATURE,
OPEN-COLLECTOR HALL-EFFECT LATCH
X
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.
PTCT
T
C
CC
2
U
D
Y
L
O
3
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.
N
R
O
P
OUTPUT
SUPPLY
1
GROUND
V
Dwg. PH-003-2
ABSOLUTE MAXIMUM RATINGS
D
E
N
U E
The A3197LLT and A3197LU are rated for operation over an extended
temperature range of -40°C to +150°C. They are supplied in a three-lead SIP
(suffix ‘U’) or a surface-mount SOT-89 (suffix ‘LT’).
R
N
I
E
T F
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 ................. 170°C
Operating Temperature Range,
TA .......................................... -40°C to +150°C
Storage Temperature, TS .................. 170°C
E
C
E
N
O R
R
C
IS FO
D —
*Fault condition, internal overvoltage shutdown
above 28 V; output current limited above 35 mA.
FEATURES
■
■
■
■
■
■
■
■
■
■
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
POWER UP &
TRANSIENT
PROTECTION
REG.
3
OUTPUT
2
GROUND
CONTROL
X
THERMAL
SHUTDOWN
CURRENT
LIMIT
<1Ω
Dwg. FH-012A
ALLOWABLE PACKAGE POWER DISSIPATION IN MILLIWATTS
800
700
Suffix "–LT"
RθJA = 180°C/W
600
Suffix "–U"
RθJA = 183°C/W
500
NOTE – Permitted duty cycle will be less than 100%
at maximum ambient temperature with high supply
voltages, i.e., TA ≥ 140°C, VCC ≥ 12 V, and the “LT”
package. The thermal shutdown circuitry does not
protect the device from these stresses (see Internal
Protective Features).
400
300
200
Suffix "E–"
100
Suffix "L–"
0
20
40
60
80
100
120
AMBIENT TEMPERATURE IN °C
2
140
160
180
Dwg. GH-054B
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1995, 2004 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
Symbol
Supply Voltage
VCC
Test Conditions
Operating (but VCC x ICC vs TA limited)
Min.
Typ.
Max.
Units
VCC(UV)
12
26
V
Overvoltage Shutdown*
VCC(OV)
B > BOP
28
—
55
V
Undervoltage Shutdown*
VCC(UV)
B > BOP
3.7
—
4.5
V
B > BOP, IOUT = 30 mA, VCC = 16 V
—
0.2
0.5
V
VOUT = 26 V
—
—
5.0
µA
B < BRP, VCC = 115 V*, IOUT = 0
28
32
40
V
B > BOP, VOUT = 12 V
35
50
70
mA
Output Voltage, On
Output Leakage Current
Output Clamp Voltage
Output Current Limit
VOUT(SAT)
IOFF
VOUT(CLMP)
IOUTMAX
Supply Current
ICC
B < BRP, VCC = 24 V, IOUT = 0
B > BOP, VCC = 24 V, IOUT = 20 mA
VCC = +115 V*
—
—
—
5.2
7.8
8.0
9.0
12
17
mA
mA
mA
Reverse Battery Current*
IRCC
VRCC = -35 V*
VRCC = -100 V*
—
—
-0.5
-2.0
-5.0
-10
mA
mA
Output Rise Time
tr
CL = 20 pF, RL = 330 Ω, VBB = 12 V
—
0.05
2.0
µs
Output Fall Time
tf
CL = 20 pF, RL = 330 Ω, VBB = 12 V
—
0.30
5.0
µs
Thermal Shutdown Temp.*
TJ
165
—
190
°C
—
—
258
183
—
—
°C/W
°C/W
Package Thermal Resist.
RθJA
“LT” Package
“U” Package
MAGNETIC CHARACTERISTICS over operating voltage range (unless otherwise specified).
Limits
Characteristic
Symbol
Operate Point
BOP
Release Point
Hysteresis
(BOP - BRP)
Test Conditions
Min.
Typ.
Max.
Units
TA = -40°C
TA = +25°C
TA = +150°C
60
50
40
130
110
105
200
160
150
G
G
G
BRP
TA = -40°C
TA = +25°C
TA = +150°C
-200
-160
-150
-140
-120
-100
-60
-50
-40
G
G
G
Bhys
TA = -40°C
TA = +25°C
TA = +150°C
150
130
110
270
230
205
—
—
—
G
G
G
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 = +25°C and VCC = 12 V (unless otherwise specified).
* Fault condition. Device is shut down and operation is not possible.
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3
3197
PROTECTED, HIGH-TEMP.,
OPEN-COLLECTOR
HALL-EFFECT LATCH
TYPICAL OPERATING CHARACTERISTICS
Switch Points
Output Saturation Voltage
500
200
400
OPERATE POINT
0
SATURATION VOLTAGE IN mV
SWITCH POINTS IN GAUSS
100
VCC = 5 V–24 V
-100
RELEASE POINT
VCC = 12 V
B ≥ BOP
300
IOUT = 30 mA
200
100
I OUT = 5 mA
-200
-50
-25
0
25
50
75
100
0
-50
150
125
-25
0
25
Dwg. GH-052-2
8.0
VCC = 24 V
SUPPLY CURRENT IN mA
B ≥ B OP
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
4
75
100
125
150
Dwg. GH-040-3
Supply Current
7.0
50
AMBIENT TEMPERATURE IN °C
AMBIENT TEMPERATURE IN ° C
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.
TEST CIRCUIT AND TYPICAL APPLICATION
VCC(UV) TO 26 V
WITH TRANSIENTS
VBB
VCC
1
RL
TO µP
3
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.
X
CBYPASS
CL
2
Dwg. EH-006A
26 V
MAX
OUTPUT VOLTAGE IN VOLTS
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.
REGULATED
< 26 V
VBB
B RP
B OP
VOUT(SAT)
0
-B
0
FLUX DENSITY
www.allegromicro.com
+B
Dwg. GH-034-2A
5
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
BOP
0
-B
BRP
VCC
0
FIRST BOP AFTER
POWER UP
VOUT
VOUT(SAT)
Dwg. WH-006
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.
BOP
0
BRP
VCC
0
FIRST BOP AFTER
TRANSIENT(S)
VOUT
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 µF to 0.5 µF capacitor,
with good high-frequency characteristics,
should be connected between terminals 1 and 2
to bypass high-voltage noise and reduce EMI
susceptibility.
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
6
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.
Test
Test Conditions (over operating temperature range)
1
Inductive Turn Off (Negative)
VS = -100 V, RS = 10 Ω, tr = 1 µs, td = 2 ms
2
Inductive Turn Off (Positive)
VS = 100 V, RS = 10 Ω, tr = 1 µs, td = 50 µs
3a
Capacitive/Inductive Coupling (Neg)
VS = -150 V, RS = 50 Ω, tr = 50 ns, td = 100 ns
3b
Capacitive/Inductive Coupling (Pos)
VS = 100 V, RS = 50 Ω, tr = 50 ns, td = 100 ns
4
Reverse Battery
VS = -14 V, td = 20 s
5
Load Dump
(ISO)
VS = 86.5 V, RS = 0.5 Ω, tr = 5 ms, td = 400 ms
(DIN)
VS = 120 V, RS = 0.5 Ω, tr = 100 ns, td = 400 ms
6
Ignition Coil Disconnect
EXTERNAL PROTECTION REQ’D
VS = -300 V, RS = 30 Ω, tr = 60 µs, td = 300 µs
7
Field Decay (Negative)
VS = -80 V, RS = 10 Ω, tr = 5 ms, td = 100 ms
0.9 V S
VS
0.1 V
S
12 V
0
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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7
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
+165°C, 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.
8
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.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3197
PROTECTED, HIGH-TEMP.,
OPEN-COLLECTOR
HALL-EFFECT LATCH
ELEMENT LOCATIONS
APPLICATIONS INFORMATION
SUFFIX “LT”
ACTIVE AREA DEPTH
0.0305"
0.775 mm
0.092"
2.35 mm
NOM
0.051"
1.30 mm
A
1
2
3
Dwg. MH-008-5B
SUFFIX “U”
ACTIVE AREA DEPTH
0.0165"
0.42 mm
0.094"
2.40 mm
NOM
0.073"
1.85 mm
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
device 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 Application Note 27703,
at
www.allegromicro.com.
A
BRANDED
SURFACE
1
2
3
Dwg. MH-002-12B
Allegro
www.allegromicro.com
9
3197
PROTECTED, HIGH-TEMP.,
OPEN-COLLECTOR
HALL-EFFECT LATCH
A3197LLT
Dimensions in Inches
(for reference only)
0.181
0.173
0.072
0.064
0.167
0.155
1
2
0.063
0.055
0.102
0.090
3
0.0173
0.0138
0.090
0.084
0.0189
0.0142
0.0221
0.0173
0.047
0.035
0.059
BSC
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
1
2
2.60
2.29
3
0.44
0.35
2.29
2.13
0.48
0.36
1.20
0.89
0.56
0.44
1.50
BSC
1.60
1.40
3.00
BSC
Dwg. MA-009-3A mm
NOTE — Exact body and lead configuration at vendor’s option within limits shown.
10
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3197
PROTECTED, HIGH-TEMP.,
OPEN-COLLECTOR
HALL-EFFECT LATCH
A3197LU
Dimensions in Inches
(controlling dimensions)
Dimensions in Millimeters
(for reference only)
0.183
0.178
4.65
4.52
0.063
0.059
1.60
1.50
0.181
0.176
4.60
4.47
45°
0.086
1
2
45°
0.018
3
2.18
MAX
1
2
0.46
3
MAX
0.0173
0.0138
0.600
0.560
0.44
0.35
15.24
14.23
0.0189
0.0142
0.48
0.36
SEE NOTE
SEE NOTE
1.27
0.050
0.100
2.54
Dwg. MH-003E in
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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11
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.
12
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
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