ATS622LSB: True Zero-Speed Hall-Effect Gear-Tooth Sensor IC

ATS622LSB
True Zero-Speed
Hall-Effect Gear-Tooth Sensor IC
Discontinued Product
These parts are no longer in production The device should not be
purchased for new design applications. Samples are no longer available.
Date of status change: May 1, 2006
Recommended Substitutions:
NOTE: For detailed information on purchasing options, contact your
local Allegro field applications engineer or sales representative.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, revisions to the anticipated product life cycle plan
for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. 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 which may result from its use.
Data Sheet
27627.105a
ATS622LSB
TRUE ZERO-SPEED
HALL-EFFECT GEAR-TOOTH SENSOR IC
4
3
2
The ATS622LSB is an optimized Hall-effect sensing integrated
circuit that provides a user-friendly solution
for true zero-speed digital gear-tooth sensing. The package
consists of a plastic shell that holds together a samarium-cobalt pellet,
a pole piece, and a Hall-effect IC that has been optimized to the
magnetic circuit. This small package can be easily assembled and used
in conjunction with a wide variety of gear shapes and sizes.
1
Pin 1 = Supply
Pin 2 = Output
Pin 3 = No Connection
Pin 4 = Ground
Dwg. AH-006-6
The integrated circuit incorporates a dual-element Hall-effect
circuit and signal processing that switches in response to differential
magnetic signals created by the ferrous gear teeth. The circuitry
contains a sophisticated digital circuit to eliminate magnet and system
offsets and to achieve true zero-speed operation (manufactured under
U.S. Pat. 5,917,320). A-to-D and D-to-A converters are used to adjust
the device gain at power on and to allow air-gap independent switching,
which greatly reduces vibration sensitivity of the device.
This system is ideal for obtaining transmission and crank
information using gear-tooth-based configurations.
FEATURES AND BENEFITS
ABSOLUTE MAXIMUM RATINGS
at TA = 25°C
Supply Voltage, VCC ........................ 26.5 V*
Reverse Supply Voltage, VRCC ............ -24 V
Continuous Output Current, IOUT ....... 20 mA
Reverse Output Current, IROUT .......... 50 mA
Package Power Dissipation,
PD .......................................... See Graph
Operating Temperature Range,
TA ............................. -40°C to +150°C*
Junction Temperature,
(continuous), TJ .......................... +165°C
(100 s), TJM ................................ +180°C
Storage Temperature, TS ................... +170°C
* Operation at increased supply voltages with
external circuitry is described in Applications
Information. Devices for operation at increased temperatures are available on special
order.
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
Tight timing accuracy over temperature
True zero-speed operation
Air-gap independent switch points
High vibration immunity
Extremely precise duty cycle signal with temperature
Large operating air gaps
Defined power-on state
Wide operating voltage range
Digital output representing gear profile
Single-chip sensing IC for high reliability
Small mechanical size (9 mm diameter x 7 mm length)
Optimized magnetic circuit
<200 µs power-on time
AGC and reference-adjust circuit
Under-voltage lockout
Some restrictions may apply to certain types of sales.
Contact factory for details.
Always order by complete part number: ATS622LSB .
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
FUNCTIONAL BLOCK DIAGRAM
1 SUPPLY
3
NO (INTERNAL)
CONNECTION
32 V
–
E1
–
+
MAGNET
X
REF
POSITIVE PEAK
DIGITAL PROC.
+
E2
NEGATIVE PEAK
DIGITAL PROC.
–
REFERENCE
GENERATOR
X
POWER-ON
LOGIC
UVLO
THRESHOLD
COMPARATORS
+
–
OUTPUT
OUTPUT
LOGIC
REG
2
+
GROUND
4
Dwg. FH-019-3
ALLOWABLE PACKAGE POWER DISSIPATION IN mW
1000
2
800
RθJA = 147°C/W
10
0
600
CO
NT
HO
UR
S
IN
UO
M
AX
.
US
400
200
0
20
40
80
120
60
100
140
AMBIENT TEMPERATURE IN °C
160
180
Dwg. GH-065-6
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 2002, 2003 Allegro MicroSystems, Inc.
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
ELECTRICAL CHARACTERISTICS at TA = +25°C (unless otherwise noted).
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Supply Voltage
VCC
Operating, TJ < 165°C
4.5
12
24
V
Power-On State
POS
VCC = 0 → 5 V
OFF
OFF
OFF
–
VCC(UV)
VCC = 0 → 5 V
4.1
4.2
4.3
V
Low Output Voltage
VOUT(SAT)
IOUT = 20 mA
–
0.2
0.4
V
Output Current Limit
IOUTM
VOUT = 12 V
25
45
55
mA
Output Leakage Current
IOFF
VOUT = 24 V
–
0.2
10
µA
Supply Current
ICC
Output off
3.5
7.0
12
mA
Output on
5.0
8.5
14
mA
Under-Voltage Lockout
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
Power-On Time
ton
Reference gear, <100 rpm
–
–
200
µs
Zener Voltage
VZ
IZT = TBD
–
32
–
V
www.allegromicro.com
3
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
OPERATION over operating voltage and temperature range with reference target (unless otherwise noted)
Limits
Characteristic
Symbol
Air Gap Range
Calibration Cycle
Calibration Update
Description
Min.
Typ.
Max.
Units
AG
Operating, target speed > 20 RPM
0.5
–
2.5
mm
ncal
Output edges before which
calibration is completed*
1
1
1
Edge
Output falling edges for startup
calibration to be complete
64
64
64
Edges
–
0
–
r/s
nr
Minimum Speed
nmin
Maximum Speed
nmax
60 teeth per second = 1 r/s
–
133
–
r/s
Timing Accuracy
tθ
Target speed = 1000 rpm,
0.5 mm < AG < 2.5 mm
–
±0.2
±0.5
°
* Non-uniform magnetic profiles may require additional output pulses before calibration is completed.
REFERENCE GEAR DIMENSIONS (60-0)
Limits
Characteristic
Min.
Typ.
Max.
Units
DO
–
120
–
mm
Tooth Width
T
–
3.0
–
mm
Valley Width
(pC – T)
–
3.0
–
mm
Valley Depth
ht
–
3.0
–
mm
Thickness
F
3.0
–
–
mm
Diameter
4
Symbol
Description
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
12
12
10
10
SUPPLY CURRENT IN mA
SUPPLY CURRENT IN mA
TYPICAL CHARACTERISTICS
8.0
6.0
4.0
B > BOP
TA = 150°C
TA = +25°C
TA = -40°C
2.0
0
0
5
10
15
20
25
4.0
0
30
B < BRP
TA = 150°C
TA = +25°C
TA = -40°C
0
5
10
15
20
25
SUPPLY VOLTAGE IN VOLTS
Dwg. GH-041-4
30
Dwg. GH-041-3
350
1.2
300
OUTPUT SATURATION VOLTAGE IN mV
1.0
SUPPLY CURRENT IN mA
6.0
2.0
SUPPLY VOLTAGE IN VOLTS
TA = 150°C
TA = +25°C
TA = -40°C
0.8
0.6
0.4
0.2
0
-30
8.0
-25
-20
-15
-10
REVERSE SUPPLY VOLTAGE IN VOLTS
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-5.0
0
Dwg. GH-031-2
B > BOP
TA = 150°C
TA = +25°C
TA = -40°C
250
200
150
100
50
0
0
5.0
10
15
20
25
OUTPUT SINK CURRENT IN mA
Dwg. GH-059-1
5
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
DEVICE DESCRIPTION
The use of the device is simple. After correct power is
applied to the component, it is capable of instantly providing digital information that is representative of the profile
of a rotating gear. No additional optimization or processing circuitry is required. This ease of use should reduce
design time and incremental assembly costs for most
applications.
Hall technology. The ATS622 contains
a single-chip differential Hall-effect sensor IC, a
samarium-cobalt pellet, and a flat ferrous pole piece.
The Hall IC consists of two Hall elements spaced 2.2 mm
apart, located so as to measure the magnetic gradient
created by the passing of a ferrous object (a gear tooth).
The two elements measure the field gradient and convert it
to a voltage that is then processed to provide a digital
output signal.
Internal electronics. The ATS622LSB is a selfcalibrating IC that contains two Hall-effect elements, a
temperature-compensated amplifier, and offset cancellation circuitry. Also contained in the device is a voltage
regulator to provide supply rejection over the operating
voltage range.
The self-calibrating circuitry is unique. After power up,
the device measures the peak-to-peak magnetic signal and
adjusts the gain using an on-chip D-to-A converter to
make the internal signal amplitude constant independent of
the installation air gap of the device. This feature allows
air-gap-independent operational characteristics.
1000
800
DIFFERENTIAL MAGNETIC FIELD IN GAUSS
Device description. The ATS622LSB true zero-speed
gear-tooth sensor IC is a Hall IC plus rare earth pellet
configuration fully optimized to provide digital detection of
gear-tooth* edges in a small package size. The IC is
packaged in a miniature plastic housing that has been
optimized for size, ease of assembly, and
manufacturability. High operating-temperature materials
are used in all aspects of construction.
600
400
200
0
-200
AG = 2.75 mm
0.25 mm INTERVALS
AG = 0.25 mm
-400
-600
-800
-1000
RELATIVE TARGET POSITION
Dwg. GH-061-2
IC
POLE PIECE
SOUTH
Magnetic signal before gain control
1000
800
RARE EARTH
PELLET
ELECTRICAL SIGNAL IN mV
600
NORTH
1
2
3
4
Dwg. MH-016-4
200
0
-200
-400
-600
AG = 2.75 mm
AG = 0.25 mm
-800
* In application, the terms “gear” and “target” are often interchanged. However, “gear” is preferred when motion is transferred.
6
400
-1000
RELATIVE TARGET POSITION
Dwg. GH-061-3
Magnetic signal after gain control
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
DEVICE DESCRIPTION — Continued
In addition to the gain control circuitry, the device also
has provisions to zero out chip, magnet, and installation
offsets. This is accomplished using two D-to-A converters
that capture the peak and valley of the signal and use them
as a reference for the switching comparator. This allows
the switch points to be precisely controlled independent of
air gap or temperature.
The two Hall transducers and the electronics are integrated on a single silicon substrate using a proprietary
BiCMOS process.
Solution advantages. The ATS622LSB true zerospeed detecting gear-tooth sensor IC is a differential Hallelement configuration. This configuration is superior in
most applications to a classical single-element GTS. The
single-element configuration commonly used requires the
detection of an extremely small signal (often <100 G) that
is superimposed on an extremely large back biased field,
often 1500 G to 3500 G. For most gear configurations, the
back-biased field values change due to concentration
effects, resulting in a varying baseline with air gap, with
valley widths, with eccentricities, and with vibration. The
differential configuration eliminates the effects of the
back-biased field through subtraction and, hence, avoids
the issues presented by the single Hall element. The
signal-processing circuitry also greatly enhances the
functionality of this device. Other advantages are
■ temperature drift — changes in temperature do not
greatly affect this device due to the stable amplifier design
and the offset rejection circuitry,
■ timing accuracy/duty cycle variation due to air gap —
the accuracy variation caused by air-gap changes is
minimized by the self-calibration circuitry. A two-to-three
times improvement can be seen over conventional zerocrossing detectors,
■ dual edge detection — because this device references
the positive and negative peaks of the signal, dual edge
detection is guaranteed,
■ tilted or off-center installation — traditional differential ICs will switch incorrectly due to baseline changes
versus air gap caused by tilted or off-center installation.
The self-calibration feature will eliminate the effect of
www.allegromicro.com
tilted installation by readjusting the switch points to the
new signal,
■ large operating air gaps — operating air gaps greater
than 2.5 mm are easily achievable with this device due to
the sensitive switch points after start up,
■ immunity to magnetic overshoot — the air-gap
independent hysteresis minimizes the impact of overshoot
on the switching of device output,
■ response to surface defects in the gear — the gainadjust circuitry reduces the effect of minor gear anomalies
that would normally causes false switching,
■ immunity to vibration and backlash — the gain-adjust
circuitry keeps the hysteresis of the device roughly proportional to the peak-to-peak signal. This allows the device to
have good immunity to vibration even when operating at
close air gaps,
■ immunity to gear run out — the differential-element
configuration eliminates the base-line variations caused by
gear run out, and
■ use with stamped-gear configurations — the highsensitivity switch points allow the use of stamped gears.
The shallow mechanical slopes created by the stamping
process create an acceptable magnetic gradient down to
zero speed. The surface defects caused by stamping the
gear are ignored through the use of gain-control circuitry.
Operation versus air-gap/tooth geometry. Operating specifications are impacted by tooth size, valley size
and depth, gear material, and gear thickness. In general,
the following guidelines should be followed to achieve
greater than 2 mm air gap from the face of unit:
■ tooth width (T) > 2 mm;
■ valley width (pC - T) > 2 mm;
■ valley depth (ht) > 2 mm;
■ gear thickness (F) > 3 mm; and the
■ gear material must be low-carbon steel.
Signal duty cycle. For regular tooth geometry, precise
duty cycle is maintained over the operating air-gap and
temperature range due to an extremely good symmetry in
the magnetic switch points of the device. For irregular
tooth geometry, there will a small but noticeable change in
pulse width versus air gap.
7
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
DEVICE DESCRIPTION — Continued
Power-on state operation. The device is guaranteed
to power on (power up) in the off state (high output
voltage) regardless of the presence or absence of a gear
tooth. Note that the circuit is ready to accurately detect the
first gear edge that results in a tooth-to-valley transition
after the circuit has successfully powered on.
Under-voltage lockout. If the supply voltage falls
below the under-voltage lockout (VCC(UV)), the device
output will turn off (high output voltage) and stay off
irrespective of the state of the magnetic field. This prevents false signals caused by under-voltage conditions
from propagating through to the output of the IC.
Output polarity. The output of the device will switch
from off to on as the leading edge of the target passes the
package in the direction indicated (pin 4 to pin 1), which
means that the output current will be low when the unit is
facing a tooth. If rotation is in the opposite direction (pin
1 to pin 4), the output of the device will switch from on to
off as the leading edge of the target passes the package,
which means that the output voltage will be low when the
unit is facing a tooth.
4
3
2
1
Output. The output of the IC 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.
Dwg. AH-006-1
APPLICATIONS INFORMATION
Power supply protection. The device contains an onchip regulator and can operate over a wide supply voltage
range. For devices that need to operate from an unregulated power supply, transient protection should be added
externally. For applications using 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.
EMI protection circuitry can easily be added to a PC
board for use with this device. Provisions have been made
for easy mounting of this board on the back of the unit.
PC board installation parallel to the device axis is also
possible.
8
4
3
2
1
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Dwg. AH-007
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
APPLICATIONS INFORMATION — Continued
The ATS622LSB is designed to minimize performance
variation (caused by the large air-gap variations resulting
from installation) by self-calibrating at power-on. These
functions should be tested using the procedures described
below.
Timing accuracy capabilities after correct self-calibration can be measured as follows:
1. Set the air gap to the desired value.
2. Power down and then power up the device.
3. Rotate the gear at the desired speed.
4. Wait for calibration to complete (128 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 operating temperature range.
There is an internal update algorithm that will maintain
the correct duty cycle as air gap changes with temperature.
Large changes in air gap will require the part to reset (by
cycling power) to maintain the correct duty cycle.
Measurement of the effect of changing air gap after
power up:
1. Set the air gap to the desired value (nominal, for
example). Rotate the target at the desired speed. Apply
power to the IC. Wait for 128 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 the
IC. Wait for update algorithm to finish adjusting
thresholds, typically 2 to 3 rotations on a 60-tooth gear.
Operation with fine-pitch gears. For targets with a
circular pitch of less than 4mm, a performance improvement can be observed by rotating the front face of the
package. This package rotation decreases the effective
element-to-element spacing and increases the capability of
detecting fine tooth or valley configurations, provided that
the Hall elements are not rotated beyond the width of the
target.
2.2 COS α
Recommended evaluation technique. The selfcalibrating feature of the ATS622LSB 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 repowered at each air gap
when gathering timing accuracy data.
2.2
α
TARGET FACE WIDTH, F
>2.2 SIN α
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A
A
Dwg. MH-018-5 mm
9
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
APPLICATIONS INFORMATION — Continued
Signal timing accuracy. The magnetic field profile
width is defined by the element spacing and narrows in degrees as the target diameter increases. This
results in improved timing accuracy performance for larger
gear diameters (for the same number of gear teeth).
Valley-to-tooth transistions will generally provide better
accuracy than tooth-to-valley transitions for large-tooth or
large-valley configurations. For highest accuracy, targets
greater than 100mm in diameter should be used.
Signal duty cycle. For repetitive target structures,
precise duty cycle is maintained over the operating air gap
and temperature range due to an extremely good symmetry
in the magnetic switch points and the internal self calibration of the device. For irregular tooth geometries, there
will be a small but measureable change in pulse width
versus air gap.
Additional applications Information on gear-tooth
and other Hall-effect devices is also available in the “HallEffect IC Applications Guide”, which can be found in the
latest issue of the Allegro MicroSystems Electronic Data
Book, AMS-701 or Application Note 27701, or at
www.allegromicro.com
CRITERIA FOR DEVICE QUALIFICATION
All Allegro devices 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
60
-55°C to +150°C
ESD,
Human Body Model
CDF-AEC-Q100-002
Pre/Post
Reading
3 per
test
Test to failure
All leads > x kV
10
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Comments
Device biased for
minimum power
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
MECHANICAL INFORMATION
Component
Package Face
Material
Function
Thermoset epoxy
Units
170
° C*
Maximum temperature
Plastic Housing
Thermoplastic PBT
264 psi deflection temp. (DTUL)
66 psi deflection temp. (DTUL)
Approximate melting temperature
204°C
216°C
225°C
Leads
Copper
—
—
Lead Finish
90/10 tin/lead solder plate
—
†
Lead Pull
—
—
8N
*Temperature excursions to 225 °C for 2 minutes or less are permitted.
† All industry-accepted soldering techniques are permitted for these packages provided the indicated maximum temperature for each component (e.g., package face, plastic housing) is not exceeded. Reasonable dwell times, which do not cause
melting of the plastic housing, should be used.
Element location (in millimeters)
(element location relative to package center is the design objective)
2.2 mm
Lead cross section (in millimeters)
0.48
0.36
0.41
NOM.
0.38
0.44
0.35
NOM.
A
0.0076
MIN. PLATING
THICKNESS
Dwg. MH-019A mm
Dwg. MH-018-4 mm
Allegro
www.allegromicro.com
11
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR IC
DIMENSIONS IN MILLIMETERS
1.27
8.8
7.0
TYP
1
2
3
7.0
4
0.41
0.38
3.9
3.0 NOM
A
0.9 DIA
8.09
2.0
8.96
Dwg. MH-017-1B mm
Tolerances, unless otherwise specified: 1 place ±0.1 mm, 2 places ±0.05 mm.
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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