ATS632LSA: Zero-Speed, Self-Calibrating, Non-Oriented, Hall-Effect Gear-Tooth Sensor IC

Data Sheet
27627.125
ATS632LSA
ZERO-SPEED, SELF-CALIBRATING,
NON-ORIENTED, HALL-EFFECT GEAR-TOOTH SENSOR
The ATS632LSA gear-tooth sensor is an optimized Hall-effect IC/
magnet combination that provides extremely accurate tooth edge
detection when used with large-pitch targets. The sensor module
consists of a high-temperature plastic shell that holds together a
compound samarium-cobalt magnet and a single-element self-calibrating Hall-effect IC that has been optimized to the magnetic circuit. This
small package, with its non-oriented operation, can be easily assembled on a PC board for complete protection and used in conjunction with a number of gear configurations.
1
2
3
4
Pin 1 = Supply
Pin 2 = Output
Pin 3 = Test Point
Pin 4 = Ground
Dwg. AH-006-2
PRELIMINARY INFORMATION
T
C
U
D
N
O
L
R
P LSB
The gear sensing technology used for this sensor is Hall-effect
based. The sensor incorporates a single-element Hall IC that switches
in response to absolute magnetic signals created by a ferrous target.
The digital output is LOW over a tooth and HIGH over a valley. The
sophisticated processing circuitry contains self-calibrating 6-bit A/D
circuitry that adapts the thresholds to the peak-to-peak signals to
minimize the effects of variation in application air gap on switch-point
timing accuracy. The effects of system and device offsets are minimized by using active offset cancellation circuitry. The digital algorithm
provides zero-speed detection capabilities without the associated
running jitter inherent in classical digital solutions.
2
D
7
E
6
S
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N yA
I
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b
N
d
e
O
c
a
C
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p
S e
I
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(subject to change without notice)
August 28, 2002
ABSOLUTE MAXIMUM RATINGS
This sensor system is ideal for use in gathering speed, position
and profile information of ferrous objects. They are particularly suited
to large tooth/valley sensing applications where accurate timing
accuracy is a desired feature. For applications requiring the sensing of
fine-pitch gears, the ATS610LSA and ATS611LSB are recommended.
Supply Voltage, VCC ......................... 24 V*
Reverse Supply Voltage, VRCC ........ -24 V
Output OFF Voltage, VOUT ................. 25 V
Output Current, IOUT .. Internally Limited
Reverse Output Current, IOUT ........ 50 mA
continued next page…
Package Power Dissipation,
PD .................................... See Graph
Operating Temperature Range,
TA ............................ -40°C to +150°C
Storage Temperature, TS ............ +170°C
* Operation at increased supply voltages with
external circuitry is described in Applications
Information.
Always order by complete part number, e.g., ATS632LSA .
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
FEATURES AND BENEFITS
■
■
■
■
■
■
ALLOWABLE PACKAGE POWER DISSIPATION IN mW
■
■
■
1000
Non-Oriented Installation
Fully Optimized Gear-Tooth Sensors
Zero-Speed Digital Output Representing Target
Profile
Large Operating Air Gaps
Extremely Low Timing Accuracy Drift with Temperature
Correct First-Edge Detection
Self-Calibrating Circuitry
with Integrated Offset Cancellation
6-bit A/D Converters to Capture Peaks
Thresholds Proportional to Peak-to-Peak Signals
Optimized Magnetic Circuit
Single-Chip Sensing IC for High Reliability
800
RθJA = 147°C/W
600
400
200
0
20
40
60
100
140
80
120
AMBIENT TEMPERATURE IN ° C
FUNCTIONAL BLOCK DIAGRAM
1
SUPPLY
POWER ON
REG
3
TEST
POINT
MAGNET
–
+
OFFSET
REFERENCE
GENERATOR
THRESHOLD
PEAK
OUTPUT
LOGIC
GAIN
X
2
OUTPUT
4
GROUND
CURRENT
LIMIT
POSITIVE PEAK
TRACK & HOLD
NEGATIVE PEAK
TRACK & HOLD
Dwg. FH-015-2
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1998, 2002 Allegro MicroSystems, Inc.
160
180
Dwg. GH-065-1
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
ELECTRICAL CHARACTERISTICS over operating voltage and temperature range (unless
otherwise specified).
Limits
Characteristic
Supply Voltage
Symbol
VCC
Test Conditions
Operating, TJ < 165°C
Min.
Typ.
Max.
Units
4.5
–
24
V
Under-Voltage Lockout
VCC(UV)
IOUT = 20 mA, VCC = 0 → 5 V
–
4.0
–
V
Low Output Voltage
VOUT(L)
IOUT = 20 mA, Output ON
–
0.2
0.4
V
Output Current Limit
IOUTM
VOUT = 12 V
25
45
55
mA
Output Leakage Current
IOFF
VOUT = 24 V, Output OFF
–
0.2
5.0
µA
Supply Current
ICC
Output OFF, Target Speed = 0 RPM
–
9.0
15
mA
Calibration Count
ncal
Output falling mechanical edges
after power on for startup calibration
to be complete
16
16
16
Pulses
Calibration Update
nup
Output falling mechanical edges
for the threshold calibration to be
complete
64
64
64
Pulses
Power-On Time
tpo
VCC > 4.5 V
–
80
500
µs
Output Rise Time
tr
RL = 500 Ω, CL = 10 pF
–
0.2
5.0
µs
Output Fall Time
tf
RL = 500 Ω, CL = 10 pF
–
0.2
5.0
µs
NOTE: Typical data is at VCC = 12 V and TA = +25°C and is for design information only.
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3
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
OPERATION over operating voltage and temperature range with reference target (unless otherwise specified).
Limits
Characteristic
Operating Air Gap Range
Output Polarity
Timing Accuracy
Symbol
AG
–
tθ
Test Conditions
Min.
Typ.
Max.
Units
Operating,
Target Speed > 20 RPM
0.3
–
2.5
mm
Operating, Over Tooth
Low
Low
Low
–
Operating, Over Valley
High
High
High
–
–
±0.25
±0.50
°
Target Speed < 3500 RPM,
0.3 mm ≤ AG ≤ 2.0 mm
TARGET DESIGN CRITERIA
Limits
Characteristic
Symbol
Description
Min.
Typ.
Max.
Units
Valley Depth
ht
–
5.0
–
mm
Valley Width
(PC - T)
–
5.0
–
mm
Tooth Width
T
–
5.0
–
mm
Thickness
F
–
5.0
–
mm
Eccentricity
–
–
–
±0.25
mm
Timing accuracy may change
TARGET DIMENSIONS
Diameter
(Do)
Thickness
(F)
Tooth Width
(T)
Valley Width
(PC - T)
Valley Depth
(ht)
Reference Target
84 mm
16 mm
9 mm
13 mm
5 mm
Characterization Target #1
84 mm
16 mm
1 tooth, 180°
5 mm
Characterization Target #2
35 mm
7 mm
1 tooth, 180°
6 mm
Type
NOTE: Timing accuracy data is taken by recalibrating the unit at each air gap.
4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
TYPICAL OPERATING CHARACTERISTICS
3.0
TARGET #1
TARGET #1
2.0
RELATIVE TIMING ACCURACY IN DEGREES
RELATIVE TIMING ACCURACY IN DEGREES
3.0
-40°C
+25°C
+150°C
1.0
RISING EDGE
0
-1.0
-2.0
-3.0
1.0
0
FALLING EDGE
-1.0
-2.0
-3.0
0.5
0.75
1.0
1.25
1.5
1.75
2.0
AIR GAP IN MILLIMETERS
2.25
0.5
0.75
1.0
1.25
1.5
1.75
Dwg. GH-063
2.25
2.0
AIR GAP IN MILLIMETERS
Dwg. GH-063-1
3.0
3.0
TARGET #2
2.0
RELATIVE TIMING ACCURACY IN DEGREES
TARGET #2
RELATIVE TIMING ACCURACY IN DEGREES
-40°C
+25°C
+150°C
2.0
-40°C
+25°C
+150°C
1.0
0
RISING EDGE
-1.0
-2.0
-40°C
+25°C
+150°C
2.0
1.0
0
FALLING EDGE
-1.0
-2.0
-3.0
-3.0
0.5
0.75
1.0
1.25
1.5
AIR GAP IN MILLIMETERS
1.75
2.0
2.25
0.5
0.75
1.0
1.25
1.5
AIR GAP IN MILLIMETERS
Dwg. GH-063-2
1.75
2.0
2.25
Dwg. GH-063-3
continued next page…
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5
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
TYPICAL OPERATING CHARACTERISTICS — Continued
51.0
51.0
TARGET #2
TARGET #1
50.0
49.5
49.0
50.0
49.5
49.0
48.5
48.5
48.0
48.0
0.5
0.75
1.0
1.25
1.5
1.75
2.0
0.5
2.25
1.25
1.5
1.75
2.0
2.25
Dwg. GH-008-4
Dwg. GH-008-3
+3
+3
RELATIVE TIMING ACCURACY IN DEGREES
RELATIVE TIMING ACCURACY IN DEGREES
1.0
0.75
AIR GAP IN MILLIMETERS
AIR GAP IN MILLIMETERS
+2
+1
0
RISING EDGE
-1
AIR GAPS
0.5 mm
1.0 mm
1.5 mm
2.0 mm
2.5 mm
-2
-3
+2
+1
0
FALLING EDGE
-1
AIR GAPS
0.5 mm
1.0 mm
1.5 mm
2.0 mm
2.5 mm
-2
-3
0
1000
2000
3000
4000
5000
REFERENCE TARGET SPEED IN RPM
6
-40°C
+25°C
+150°C
50.5
-40°C
+25°C
+150°C
DUTY CYCLE IN PER CENT
DUTY CYCLE IN PER CENT
50.5
6000
7000
Dwg. GH-064-1
0
1000
2000
3000
4000
5000
REFERENCE TARGET SPEED IN RPM
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
6000
7000
Dwg. GH-064-2
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
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
Test Method and
Test Conditions
Test Length
Samples
Per Lot
Temperature Humidity
Bias Life
JESD22-A101,
TA = 85°C, RH = 85%
1000 hrs
48
Bias Life
JESD22-A108,
TA = 150°C, TJ = 165°C
1000 hrs
48
(Surge Operating Life)
JESD22-A108,
TA = 175°C, TJ = 190°C
168 hrs
48
Autoclave, Unbiased
JESD22-A102,
TA = 121°C, 15 psig
96 hrs
48
High-Temperature
(Bake) Storage Life
JESD22-A103,
TA = 170°C
1000 hrs
48
Temperature Cycle
JESD22-A104
1000 cycles
48
-55°C to +150°C
ESD,
Human Body Model
CDF-AEC-Q100-002
Pre/Post
Reading
3 per
test
Test to failure
Pin 3 > 1.5 kV
All leads > 8 kV
Comments
Device biased for
minimum power
APPLICATIONS INFORMATION
Recommended Evaluation Technique. The selfcalibrating feature of the ATS632LSA requires that a
special evaluation technique be used to measure its highaccuracy performance capabilities. Installation inaccuracies are calibrated out at power on; hence, it is extremely
important that the device be re-powered at each air gap
when gathering timing accuracy data.
Self-Calibrating Functions. These sensors are designed to minimize performance variation caused by the
large air gap variations resulting from installation by selfcalibrating at power-on. They are also designed to
minimize performance variation caused by the smaller,
slower air gap changes resulting from temperature
change and gear run-out during continuous operation by
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updating the self-calibration periodically (after every 64
output pulses) if necessary. These two functions should
be tested using the following procedure.
1. Set the air gap to the desired value.
2. Power down and then power on the device.
3. Rotate the target at the desired speed.
4. Wait for calibration to complete (16 output pulses to
occur).
5. Monitor output for correct switching and measure
accuracy.
6. Repeat the above for multiple air gaps within the
operating range of the device.
7. This can be repeated over the entire temperature
range.
7
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
APPLICATIONS INFORMATION — Continued
Measurement of the effect of changing air gap after power
on:
1. Set the air gap to the desired value (nominal, for
example). Rotate the target at the desired speed.
Apply power to the module. Wait for 16 output pulses
to occur. Monitor output for correct switching and
measure accuracy.
2. Change the air gap by ± 0.25 mm. Do not re-power
module. Wait for 64 output pulses to occur. Monitor
the output for correct switching and measure accuracy.
Operation with Fine-Pitch Gears. The self-calibration
routines allow the detection of fine-pitch gears once the
target is rotating. The major issue in these applications is
the impact of gear run-out on the baseline of the magnetic
field. Excessive run-out may result in tooth edges not
being detected.
Device Switch Points. The device switch points are
referenced to the peak-to-peak values of the gain-adjusted signal. The comparator thresholds have been
chosen to provide timing accuracy, as well as limited
immunity from mis-detection caused by short valley
conditions or by gear run-out.
Output. The output of the sensor is a short-circuitprotected open-collector stage capable of sinking 20 mA.
An external pull-up (resistor) to a supply voltage of not
more than 24 V must be supplied.
Gear Design Criteria.* The system was designed to
work correctly with minimum valley depths of 5 mm and
minimum valley widths of 13 mm. As the valley depth
decreases, the valley field rises above the open-circuit
value of the magnetic circuit when the sensor is at minimum air gap. The same is true when the valley width
decreases. In both cases, the metal mass from the valley
bottom or side walls provides an interference at minimum
air gap and will provide a signal that may be interpreted
as a tooth upon power on. It is important to note that this
anomaly will normally only affect the power-on state of the
device and the self-calibration circuitry will null this
baseline shift when the device is in running mode.
* In application, the terms “gear” and “target” are often
interchanged. However, “gear” is preferred when motion
is transferred.
Signal Duty Cycle. For regular tooth geometries, precise
duty cycle is maintained over the operating air gap and
temperature range due to the good symmetry of the
magnetic switch points of the device.
Output Polarity. The switching of the output is independent of the direction of gear rotation.
Power Supply Protection. The device contains an onchip regulator and can operate over a wide supply voltage
range (4.5 V to 24 V). For devices that need to operate
from an unregulated power supply, transient protection
must be added externally. For applications being run off a
regulated line, EMI/RFI protection is still required. Incorrect protection can result in unexplained pulses on the
output line, providing inaccurate sensing information to
the user.
Signal-Timing Accuracy. Timing accuracy is improved
with larger gear diameters. The magnetic field profile has
a defined spread that narrows in degrees as the target
diameter increases. The slope of this magnetic profile
also changes with air gap. For highest accuracy, targets
greater than 100 mm diameter should be used.
8
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
continued next page…
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
APPLICATIONS INFORMATION — Continued
The protection circuitry can easily be added to a PC
board for use with this device. Provisions have been
made for easy mounting of a PC board on the back of the
unit. PC board installation parallel to the device axis is
also possible.
Operation From a Regulated Power Supply. These
devices require minimal protection circuitry during operation from a low-voltage regulated line. The on-chip
voltage regulator provides immunity to power supply
variations between 4.5 V and 24 V. However, even while
operating from a regulated line, some supply and output
filtering is required to provide immunity to coupled and
injected noise on the supply line. A basic RC low-pass
filter circuit (R1C1) on the supply line and an optional
output capacitor (C2) is recommended for operation in
noisy environments. In extremely noisy environments, a
filter capacitor at pin 3 may also be required. Because the
device has an open collector output, an output pull-up
resistor must be added either at the sensor module or at
the controller.
SUPPLY
OUTPUT
C2
100 pF
RL
4
3
2
1
Dwg. AH-007
20 Ω
R1
C1
0.033 µF
100 pF
C3
1
2
3
4
Vcc
X
Dwg. EH-008-3A
continued next page…
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9
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
APPLICATIONS INFORMATION — Continued
Operation from an Unregulated Power Supply. In
applications where the device gets its power from an
unregulated supply such as an automotive battery, full
protection is generally required. In addition to supply
regulation, such applications require the device to withstand various supply side transients. Specifications for
such transients vary between car manufacturers and
protection circuit design should be optimized for each
application. In the circuit shown below, a simple Zenercontrolled regulator is constructed using discrete components. The RC low-pass filter on the supply line (R1C1)
and a low-value supply bypass capacitor (CS) can be
included, if necessary, so as to minimize the susceptibility
to EMI/RFI. The NPN should be chosen with sufficiently
high forward breakdown voltage so as to hold off supplyside transients. The series diode should be chosen with
sufficiently high reverse breakdown capabilities so as to
withstand the most negative transient. The current-limiting
resistor (RZ) and the Zener diode should be sized for
power dissipation requirements.
OUTPUT
SUPPLY
C2
100 pF
RL
20 Ω
R1
2.5 kΩ
RZ
0.1 µF
CS
C1
0.033 µF
100 pF
C3
6.8 V
1
2
3
4
Vcc
X
Dwg. EH-008-2A
Additional applications Information on gear-tooth and
other Hall-effect sensors is provided in the Allegro Integrated and Discrete Semiconductors Data Book or
Application Note 27701.
10
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
MECHANICAL INFORMATION
Component
Material
Function
Units
Sensor Face
Thermoset epoxy
Maximum temperature
170°C*
Plastic Housing
Polyamide, 33% glass filled
264 psi deflection temp. (DTUL)
225°C
(Nylon 6, 6)
Approximate melting temperature
260°C
Leads
Copper
–
–
Lead Pull
–
–
8N
Lead Finish
90/10 tin/lead solder plate
–
†
Flame Class Rating
–
–
UL94V-0
*Temperature excursions to 225 °C for 2 minutes or less are permitted.
†All industry-accepted soldering techniques are permitted for these modules provided the indicated maximum
temperature for each component (e.g., sensor face, plastic housing) is not exceeded. Reasonable dwell times,
which do not cause melting of the plastic housing, should be used.
Sensor Location (in millimeters)
Lead Cross-Section (in millimeters)
(sensor location relative to package center is the design
objective)
0.48
0.36
0.41
NOM.
0.1
0.44
0.35
0.38
NOM.
A
Dwg. MH-018-2 mm
0.0076
MIN. PLATING
THICKNESS
Dwg. MH-019A mm
continued next page…
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11
ATS632LSA
HALL-EFFECT
GEAR-TOOTH SENSOR
DIMENSIONS IN MILLIMETERS
1.27
7.25
5.00
TYP
1
2
3
9.0
4
0.41
0.38
3.9
3.0 NOM
0.9 DIA
A
8.3
8.0
2.0
9.0
SEE NOTE
Dwg. MH-017A mm
Tolerances unless otherwise specified:1 place ±0.1 mm, 2 places ±0.05 mm.
NOTE — Nominal dimension and tolerances dependent on package material. Contact factory.
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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