ATS665LSG: True Zero-Speed, Hall-Effect Adaptive Gear-Tooth Sensor IC

ATS665LSG
True Zero Speed, High Accuracy, 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: January 31, 2011
Recommended Substitutions:
For existing customer transition, and for new customers or new applications, refer to the ATS667.
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.
ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Features and Benefits
Description
▪ True zero-speed operation
▪ Switchpoints independent of air gap
▪ High vibration immunity
▪ Precise duty cycle signal over operating temperature range
▪ Large operating air gaps
▪ Defined power-on state
▪ Wide operating voltage range
▪ Digital output representing target profile
▪ Single-chip sensing IC for high reliability
▪ Small mechanical size
▪ Optimized Hall IC magnetic system
▪ 200 μs power-on time at gear speed < 100 rpm
▪ AGC and reference adjust circuit
▪ Undervoltage lockout
The ATS665 true zero-speed gear tooth sensor IC is an optimized
Hall IC/rare earth pellet configuration designed to provide a
user-friendly solution for digital gear tooth sensing applications.
The over-molded package, holds together a samarium cobalt
pellet, a pole piece and a true zero-speed Hall IC that has been
optimized to the magnetic circuit. This small package can be
easily assembled and used in conjunction with gears of various
shapes and sizes.
Package: 4-pin SIP (suffix SG)
The device incorporates a dual element Hall IC that switches
in response to differential magnetic signals created by
a ferromagnetic target. The IC contains a sophisticated
compensating circuit designed to reduce the detrimental effects
of magnet and system offsets. Digital processing of the analog
signal provides zero speed performance independent of air
gap and also dynamic adaptation of device performance to the
typical operating conditions found in automotive applications
(reduced vibration sensitivity). High-resolution peak detecting
DACs are used to set the adaptive switching thresholds of the
device. Hysteresis in the thresholds reduces the negative effects
of any anomalies in the magnetic signal associated with the
targets used in many automotive applications.
Continued on the next page…
Not to scale
Functional Block Diagram
Vcc
Vsig
INTERNAL
HALL AMP
AUTOMATIC
GAIN
CONTROL
REGULATOR
THRESHP
REFERENCE
GENERATOR
PDAC
ATS665-DS, Rev. 4
THRESH
LOGIC
OUTPUT
Output
Transisto
r
PPEAK
THRESHN
NDAC
THRESHOLD
COMPARATOR
NPEAK
Current
Limit
GND
ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Description (continued)
This ATS665’s ability to provide tight duty cycle at high speeds and
over a wide temperature range makes it ideal for transmission and
industrial speed applications. The ATS665 is available in the SG
package in the automotive temperature range, -40° to 150° (L). It
is lead (Pb) free with 100% matte tin leadframe plating
Selection Guide
Part Number
Packing*
ATS665LSGTN-T
800 pieces per reel
*Contact Allegro® for additional packing options
Absolute Maximum Ratings
Characteristic
Symbol
Supply Voltage
VCC
Reverse Supply Voltage
VRCC
Reverse Output Current
IRCC
Continuous Output Current
IOUT
4
–18
V
50
mA
ºC
TJ(max)
165
ºC
Tstg
–65 to 170
ºC
Maximum Junction Temperature
3
V
mA
Storage Temperature
2
Unit
26.5
20
TA
1
VOUT ≥ –0.5 V
Rating
–40 to 150
Operating Ambient Temperature
Pin-out Diagram
Notes
See Power Derating section
Range L
Terminal List
Number
Name
Function
1
VCC
Device supply
2
VOUT
Device output
3
–
4
GND
Tie to GND or float
Ground
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115 Northeast Cutoff
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ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
OPERATING CHARACTERISTICS Valid at TA = –40°C to 150°C over air gap, typical operating parameters VCC = 12 V and
TA = 25°C; unless otherwise noted
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
3.3
–
24
V
–
–
<VCC(min)
V
–
–
–10
mA
26.5
–
–
V
–
Iccon(max)
+3
mA
Electrical Characteristics
Supply Voltage
Undervoltage Lockout
Reverse Supply Current
Supply Zener Clamp Voltage
Supply Zener Current
Supply Current
VCC
Operating; TJ < TJ(max)
VCC(UV)
IRCC
VZ
IZ
ICC
VCC = –18 V
ICC = Iccon(max) + 3 mA, TA = 25°C
Test only; VCC = 28 V, TJ < TJ(max)
–
Output off
–
8
14
mA
Output on
–
8
14
mA
–
High
–
–
–
–
200
μs
Power-On State Characteristics
Power-On State
SPO
Power-On Time
tPO
Gear speed < 100 rpm; VCC > VCC(min)
Output Stage
Low Output Voltage
Vsat
Output = on, ISINK = 20 mA
–
225
400
mV
Output Current Limit
Ilim
VOUT = 12 V, TJ < TJ(max)
25
45
70
mA
Output Leakage Current
IOFF
Output = off, VOUT = 24 V
–
–
10
μA
Output Rise Time
tr
RLOAD = 500 Ω, CLOAD = 10 pF
–
1.0
2
μs
Output Fall Time
tf
RLOAD = 500 Ω, CLOAD = 10 pF
–
0.6
2
μs
S
Reference target
0
–
12000
rpm
Switchpoint Characteristics
Target Speed
Bandwidth
f-3dB
–
20
–
kHz
Operate Point
BOP
% of peak-to-peak signal, AG < AG(max)
–
70
–
%
Release Point
BRP
% of peak-to-peak signal, AG < AG(max)
–
30
–
%
Initial Calibration
Start-up, power-on speed ≤ 200 rpm
–
2
6
Edges
Calibration Update
Running mode operation
Calibration
Continuous
Operating Characteristics (with 60-0 reference target)
Operational Air Gap
AG
Measured from package face to top of target
tooth
0.5
–
2.5
mm
Duty Cycle
AG < AG(max), reference target
42
47
52
%
Operating Signal
Duty cycle spec compliance
60
–
–
G
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ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Characteristic Performance
IccOn
IccOn
14
14
12
12
10
-40
0
8
25
6
85
4
150
Icc [mA]
Icc [mA]
10
12
6
20
26.5
4
°C
2
4.3
8
Vcc
2
0
0
0
10
20
-50
30
0
50
100
150
Temperature [°C]
Vcc [V]
IccOff
IccOff
14
12
12
10
Icc [mA]
10
-40
0
8
25
6
85
4
150
°C
2
Icc [mA]
14
4.3
8
12
6
20
26.5
4
Vcc
2
0
-50
0
0
10
20
0
50
100
150
Temperature [°C]
30
Vcc [V]
Vsat
Output Voltage [mV]
400
350
300
250
200
150
100
50
-50
0
50
100
150
200
Temperature [°C]
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Duty Cycle 100 RPM
53
0.4
0.5
0.8
1.5
2.35
2.5
52
51
Duty Cycle [% ]
Duty Cycle [% ]
Duty Cycle 100 RPM
53
52
51
50
49
48
47
46
45
44
43
0
50
100
-40
49
48
0
25
47
85
46
150
45
44
Air
gap
-50
50
°C
43
150
0
1
3
Duty Cycle @ 1000 RPM
Duty Cycle 1000 RPM
53
52
53
52
51
50
49
48
47
46
45
44
43
0.4
0.5
0.8
1.5
2.35
2.5
Air
gap
-50
0
50
100
Temperature [°C]
150
Duty Cycle [% ]
Duty Cycle [% ]
2
Air Gap [mm]
Temperature [°C]
51
50
49
-40
0
25
85
48
47
46
45
150
°C
44
43
0
1
2
3
Air Gap [mm]
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115 Northeast Cutoff
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ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Reference Target / Gear Information
Diameter
120
mm
Thickness
6
mm
Tooth Width
3
mm
Valley Width
3
mm
Valley Depth
3
mm
Material
Low carbon steel
Allegro MicroSystems, Inc.
115 Northeast Cutoff
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ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Functional Description
Device Description
The ATS665 true zero speed gear tooth sensor IC is a Hall IC/
rare earth pellet configuration that is fully optimized to provide
digital detection of gear tooth edges. This device is integrally
molded into a plastic body that has been optimized for size, ease
of assembly, and manufacturability. High operating temperature
materials are used in all aspects of construction.
Hall Technology
The device 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 which
measure the magnetic gradient created by the passing of a ferrous
object. The gradient is converted to an analog voltage that is then
processed to provide a digital output signal.
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115 Northeast Cutoff
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7
ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Operation
After proper power is applied to the component the IC is then
capable of providing digital information that is representative
of the profile of a rotating gear. No additional optimization is
needed and minimal processing circuitry is required. This ease of
use should reduce design time and incremental assembly costs for
most applications. The following output diagram is indicative of
the ICr performance for the polarity indicated in the figure at the
bottom of the page.
Output Polarity
The output of the IC will switch from low to high as the leading edge of the tooth passes the package face in the direction
indicated in the figure below. In this system configuration, the
output voltage will be high when the package is facing a tooth. If
rotation occurs in the opposite direction, the output polarity will
invert.
Power-On State Operation:
The device is guaranteed to power up in the off state (logic high
output).
MECHANICAL PROFILE
High over Tooth
MAGNETIC PROFILE
IC ELECTRICAL OUTPUT PROFILE
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ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Start-up Detection
Since the IC powers-up in the off state (logic high output), the first
edge seen by the IC can be missed if the switching induced by that
edge reinforces the off state. Therefore, the first edge that can be
guaranteed to induce an output transition is the second detected edge.
This device has accurate first electrical falling edge detection. The
tables below show various start-up schemes.
MECHANICAL
TARGET PROFILE
MAGNETIC PROFILE
(High over Tooth)
IC OUTPUT
High over Tooth
(Start-up over Valley)
(Start-up over Rising Edge)
(Start-up over Tooth)
(Start-up over Falling Edge)
IC start-up location
MECHANICAL
TARGET PROFILE
MAGNETIC PROFILE
(Low over Tooth)
IC OUTPUT
(Start-up over Valley)
Low over Tooth
(Start-up over Rising Edge)
(Start-up over Tooth)
(Start-up over Falling Edge)
IC start-up location
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Undervoltage Lockout
When the supply voltage falls below the minimum operating voltage, VCCUV , the device turns off and stays off irrespective of the
state of the magnetic field. This prevents false signals caused by
undervoltage conditions from propagating to the output of the IC.
Power Supply Protection
The device contains an on-chip regulator and can operate over a
wide supply voltage range. For devices that need to operate from
an unregulated power supply, transient protection must be added
externally. For applications using a regulated line, EMI/RFI
protection may still be required. The following circuit is the most
basic configuration required for proper device operation. For
EMC information, contact your Allegro representative.
Internal Electronics
The ATS665 contains a self-calibrating Hall effect IC that possesses two Hall elements, a temperature compensated amplifier
and offset cancellation circuitry. The IC also contains a voltage
regulator that provides supply noise rejection over the operating
voltage range. The Hall transducers and the electronics are integrated on the same silicon substrate using a proprietary BiCMOS
process. Changes in temperature do not greatly affect this device
due to the stable amplifier design and the offset rejection circuitry.
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ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Automatic Gain Control (AGC)
The patented self-calibrating circuitry is unique. After each
power up, the device measures the peak-to-peak magnetic signal.
The gain of the IC is then adjusted which keeps the internal signal
amplitude constant over the air gap range of the device. This feature provides operational characteristics independent of air gap.
Offset Adjust
In addition to normalizing performance over air gap, the gain
control circuitry also reduces the effect of chip, magnet, and
installation offsets. This is accomplished using two D/A converters that capture the peak and valley of the signal and use it as a
reference for the switching comparator. If induced offsets bias the
absolute signal up or down, AGC and the dynamic DAC behavior work to normalize and reduce the impact of the offset on IC
performance.
DIFFERENTIAL MAGNETIC SIGNAL
WITH INCREASING AIR GAP
DIFFERENTIAL ELECTRICAL SIGNAL
WITH INCREASING AIR GAP
800
600
400
200
1000
0.25 mm
0.50 mm
1.00 mm
1.50 mm
2.00 mm
0
-200
-400
-600
-800
-1000
DIFFERENTIAL SIGNAL [mV]
MAGNETIC FLUX DENSITY
[GAUSS]
1000
0.25 mm
800
0.50 mm
600
1.00 mm
400
1.50 mm
200
2.00 mm
0
-200
-400
-600
-800
-1000
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
TARGET POSITION [DEGREES]
TARGET POSITION [DEGREES]
Magnetic Signal with no Amplification
Electrical Signal after AGC
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ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Switchpoints
Switchpoints in the ATS665 are established dynamically as a percentage of the amplitude of the normalized magnetic signal. Two
DACs track the peaks of the normalized magnetic signal (see the
section on Update); the switching thresholds are established at
30% and 70% of the two DAC’s values. The proximity of the
thresholds near 50% ensures the most accurate and consistent
switching where the signal is steepest and least affected by air
gap variation.
The hysteresis of 40% provides high air gap performance and
immunity to false switching on noise, vibration, backlash and
other transient events. Since the hysteresis value is independent
of air gap, it provides protection against false switching in the
presence of overshoot that can be induced on the edges of large
teeth.
The figure below graphically demonstrates the establishment of
the switching threshold levels. Because the threshold are established dynamically as a percentage of the peak-peak signal, the
effect of a baseline shift is minimized. As a result, the effects of
offsets induced by tilted or off-center installation are minimized.
Switching Threshold Levels
Bop
100 %
70 %
30 %
0%
Brp
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ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Update
The ATS665 incorporates an algorithm that continuously monitors the system and updates the switching thresholds accordingly.
The switchpoint for each edge is determined by the previous
two edges. Since variations are tracked in real time, the IC has
high immunity to target run-out and retains excellent accuracy
and functionality in the presence of both run-out and transient
mechanical events. The figures below show how the IC uses historical data to provide the switching threshold for a given edge.
Switching Level - Operate
Operate point
based on previous
two peaks
Switching Level - Release
Release point
based on previous
two peaks
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True Zero Speed, High Accuracy, Gear Tooth Sensor IC
IC/Target Evaluation
In order to establish the proper operating specification for a particular IC/target system, a systematic evaluation of the magnetic
circuit should be performed. The first step is the generation of
a magnetic map of the target. By using a calibrated device, a
magnetic signature of the system is made. At right is a map of
the 60-0 reference target. Flux density shown is the differential of
the magnetic fields sensed at the two Hall elements.
A single curve is distilled from this map data that describes the
peak-peak magnetic field versus air gap. Knowing the minimum
amount of magnetic flux density that guarantees operation of the
IC, one can determine the maximum operational air gap of the
IC/target system. Referring to the chart below right, a minimum
required peak-peak signal of 60 G corresponds to a maximum air
gap of approximately 2.5 mm.
300
250
200
150
Flux Density [Gauss]
ATS665LSG
100
50
0
-50
-100
-150
-200
-250
-300
0
5
Target Design
For the generation of adequate magnetic field levels to maximize
air gap performance, the following recommendations should be
followed in the design and specification of targets.
Accuracy
While the update algorithm will allow the IC to adapt to system
changes (i.e. air gap increase), major changes in air gap can
adversely affect switching performance. When characterizing IC
performance over a significant air gap range, be sure to re-power
the device at each air gap. This ensures that self-calibration
occurs for each installation condition. See the section entitled
Characteristic Data for typical duty cycle performance.
20
0.94mm
1.19mm
1.44mm
1.69mm
1.94mm
Tooth width > 2 mm
Valley width > 2 mm
Valley depth > 2 mm
Gear thickness > 3 mm
Target material must be low carbon steel
Though these parameters apply to targets of traditional geometry
(radially oriented teeth with radial sensing), they can be applied
to stamped targets as well. For stamped geometries with axial
sensing, the valley depth is intrinsically infinite so the criteria for
tooth width, valley width, material thickness (can be < 3 mm) and
material specification need only be considered.
15
25
30
35
Position [º]
2.19mm
2.44mm
2.69mm
2.94mm
3.19mm
ATS665LSG 60-0 TARGET MAP
700
600
Peak-Peak Flux Density [Gauss]
·
·
·
·
·
10
500
400
300
200
100
0
0.5
1
1.5
2
2.5
3
3.5
Air Gap [mm]
Allegro MicroSystems, Inc.
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14
ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Power Derating
Due to internal power consumption, the junction temperature of the
IC, TJ, is higher than the ambient environment temperature, TA. To
ensure that the device does not operate above the maximum rated
junction temperature use the following calculations:
ΔT = PD × RθJA
If:
ΔT = PD × RθJA
Then, at TA = 150°C:
PD(max) = ΔT(max) / RθJA = 15°C / 126°C/W = 119 mW
If:
Where:
PD = VCC × ICC
∴ ΔT = VCC × ICC × RθJA
Where ΔT denotes the temperature rise resulting from the IC’s
power dissipation.
TJ = TA + ΔT
PD = VCC × ICC
Then the maximum VCC at 150°C is therefore:
VCC(max) = PD(max) / ICC = 119 mW / 12.0 mA = 9.9 V
This value applies only to the voltage drop across the 665 chip. If
a protective series diode or resistor is used, the effective maximum
supply voltage is increased.
For the IC:
For example, when a standard diode with a 0.7 V drop is used:
TJ(max) = 165°C
RθJA = 126°C/W
VS(max) = 9.9 V + 0.7 V = 10.6 V
Typical TJ calculation:
Maximum Allowable Power Dissipation Calculation for ATS665:
Assume:
If:
TA = TA(max) = 165°C
TJ(max) = 165°C
ICC = 12.0 mA
TJ = TA + ΔT
Then, at TA = 150 °C:
ATS665LSG Package Power De-Rating Curve
Thermal Resistance = 126°C/Watt, Tjmax = 165°C
Maximum Supply Voltage [Volts]
TA = 25°C
VCC = 5 V
ICC = 7.0 mA
PD = VCC × ICC = 5 V × 8.0 mA = 40.0 mW
ΔT = PD × RθJA = 40.0 mW × 126°C/W = 5.0°C
TJ = TA + ΔT = 25°C + 5.0°C = 30.0°C
30.0
28.0
26.0
24.0
22.0
20.0
18.0
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
c
20
40
60
80
100
120
140
160
180
Ambient Temperature [°C]
ΔT(max) = TJ(max) – TA(max) = 165°C –150°C = 15°C
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15
ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Package SG 4-Pin SIP
5.50±0.05
F 1.10
1.10 F
E
B
8.00±0.05
LLLLLLL
NNN
5.80±0.05
E1
E2
YYWW
Branded
Face
1.70±0.10
D
4.70±0.10
1
2
3
4
= Supplier emblem
L = Lot identifier
N = Last three numbers of device part number
Y = Last two digits of year of manufacture
W = Week of manufacture
A
0.60±0.10
Standard Branding Reference View
0.71±0.05
For Reference Only, not for tooling use (reference DWG-9002)
Dimensions in millimeters
A Dambar removal protrusion (16X)
+0.06
0.38 –0.04
B Metallic protrusion, electrically connected to pin 4 and substrate (both sides)
C Thermoplastic Molded Lead Bar for alignment during shipment
24.65±0.10
D Branding scale and appearance at supplier discretion
0.40±0.10
15.30±0.10
E
Active Area Depth, 0.43 mm
F
Hall elements (E1, E2), not to scale
1.0 REF
A
1.60±0.10
C
1.27±0.10
0.71±0.10
0.71±0.10
5.50±0.10
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115 Northeast Cutoff
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16
ATS665LSG
True Zero Speed, High Accuracy, Gear Tooth Sensor IC
Copyright ©1993-2009, Allegro MicroSystems, Inc.
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’s products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the
failure of that life support device or system, or to affect the safety or effectiveness of that device or system.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use;
nor for any infringement of patents or other rights of third parties which may result from its use.
For the latest version of this document, visit our website:
www.allegromicro.com
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