Datasheet ATS622LSB Datasheet (Allegro)

Page 1
ATS622LSB
TRUE ZERO-SPEED
HALL-EFFECT GEAR-TOOTH SENSOR
Data Sheet
27627.105
1
2
3
4
Pin 1 = Supply
Pin 2 = Output
Pin 3 = No Connection
Pin 4 = Ground
Dwg. AH-006-6
PRELIMINARY INFORMATION
(subject to change without notice)
October 20, 2000
ABSOLUTE MAXIMUM RATINGS
at T
= 25°C
A
Supply Voltage, VCC........................ 26.5 V*
Reverse Supply Voltage, V Continuous Output Current, I Reverse Output Current, I 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.
............ -24 V
RCC
OUT
.......... 50 mA
ROUT
....... 20 mA
The ATS622LSB is an optimized Hall-effect sensing integrated
circuit and magnet combination that provides a user-friendly solution for true zero-speed digital gear-tooth sensing. The sensor subassembly consists of a plastic shell that holds together a samarium-cobalt magnet, a pole piece, and a Hall-effect sensor 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.
The integrated circuit incorporates a dual-element Hall-effect sensor 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 sensor system is ideal for obtaining transmission and crank information using gear-tooth-based configurations.
FEATURES AND BENEFITS
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 .
Page 2
ATS622LSB
TRUE ZERO-SPEED, GEAR-TOOTH SENSOR
FUNCTIONAL BLOCK DIAGRAM
MAGNET
Dwg. FH-019-3
1000
SUPPLY1
3
NO (INTERNAL)
CONNECTION
32 V
REG
X
E1
X
E2
+
REF
+
POSITIVE PEAK
DIGITAL PROC.
NEGATIVE PEAK
DIGITAL PROC.
UVLO
POWER-ON
LOGIC
REFERENCE
GENERATOR
THRESHOLD
COMPARATORS
+
+
LOGIC
OUTPUT
OUTPUT
2
GROUND
4
800
1
0
0
H
O
600
400
200
0
ALLOWABLE PACKAGE POWER DISSIPATION IN mW
40 80 120
C
60 100 140 18020
AMBIENT TEMPERATURE IN °C
U
R
O
N
S
T
M
IN
U
O
U
S
2
R
θJA
= 147°C/W
A
X
.
160
Dwg. GH-065-6
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 2000, Allegro MicroSystems, Inc.
Page 3
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR
ELECTRICAL CHARACTERISTICS at TA = +25°C (unless otherwise noted).
Limits
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Supply Voltage V
CC
Operating, TJ < 165°C 4.5 12 24 V
Power-On State POS VCC = 05 V OFF OFF OFF
Under-Voltage Lockout V
Low Output Voltage V
OUT(SAT)
Output Current Limit I
Output Leakage Current I
Supply Current I
CC(UV)
OUTM
OFF
CC
VCC = 0 → 5 V 4.1 4.2 4.3 V
I
= 20 mA 0.2 0.4 V
OUT
V
= 12 V 254555 mA
OUT
V
= 24 V 0.2 10 µA
OUT
Output off 3.5 7.0 12 mA
Output on 5.0 8.5 14 mA
Output Rise Time t
Output Fall Time t
Power-On Time t
Zener Voltage V
r
f
on
Z
RL = 500 , CL = 10 pF 0.2 5.0 µs
RL = 500 , CL = 10 pF 0.2 5.0 µs
Reference gear, <100 rpm 200 µs
IZT = TBD 32 V
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Page 4
ATS622LSB
TRUE ZERO-SPEED, GEAR-TOOTH SENSOR
OPERATION over operating voltage and temperature range with reference target (unless oth­erwise noted)
Limits
Characteristic Symbol Description Min. Typ. Max. Units
Air Gap Range AG Operating, target speed > 20 RPM 0.5 2.5 mm
Calibration Cycle n
cal
Output edges before which 1 1 1 Edge
calibration is completed*
Calibration Update n
r
Output falling edges for startup 128 128 128 Edges
calibration to be complete
Minimum Speed n
Maximum Speed n
Timing Accuracy t
min
max
θ
60 teeth per second = 1 r/s 133 r/s
Target speed = 1000 rpm, ±0.2 ±0.5 °
–0– r/s
0.5 mm < AG < 2.5 mm
* Non-uniform magnetic profiles may require additional output pulses before calibration is completed.
REFERENCE GEAR DIMENSIONS (60-0)
Limits
Characteristic Symbol Description Min. Typ. Max. Units
Diameter D
O
Tooth Width T 3.0 mm
120 mm
Valley Width (pC – T) 3.0 mm
Valley Depth h
t
–3.0– mm
Thickness F 3.0 mm
4
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
Page 5
TYPICAL CHARACTERISTICS
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR
12
10
8.0
6.0
4.0
SUPPLY CURRENT IN mA
2.0
0
0
5
SUPPLY VOLTAGE IN VOLTS
12
10
8.0
6.0
4.0
B > BOP
TA = 150°C
A = +25°C
T
A = -40°C
T
10
15 20 25
30
Dwg. GH-041-4
SUPPLY CURRENT IN mA
2.0
0
0
5
SUPPLY VOLTAGE IN VOLTS
10
15 20 25
B < B
TA = 150°C
A
= +25°C
T
A
= -40°C
T
RP
30
Dwg. GH-041-3
1.2
1.0
0.8
0.6
0.4
SUPPLY CURRENT IN mA
0.2
0
-30
-25
REVERSE SUPPLY VOLTAGE IN VOLTS
-20
TA = 150°C
A = +25°C
T
A = -40°C
T
-15 -10 -5.0
Dwg. GH-031-2
350
300
250
200
150
100
50
B > B
TA = 150°C
A
= +25°C
T
A
= -40°C
T
OP
OUTPUT SATURATION VOLTAGE IN mV
0
0
0
5.0
10 15 20 25
OUTPUT SINK CURRENT IN mA
Dwg. GH-059-1
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Page 6
ATS622LSB
TRUE ZERO-SPEED, GEAR-TOOTH SENSOR
DEVICE DESCRIPTION
Subassembly description. The ATS622LSB true
zero-speed gear-tooth sensor system is a Hall IC plus magnet configuration that is fully optimized to provide digital detection of gear-tooth* edges in a small package size. The sensor 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.
The use of the sensor 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.
Sensing technology. The gear-tooth sensor subassem­bly contains a single-chip differential Hall-effect sensor IC, a samarium-cobalt magnet, 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.
SENSOR
POLE PIECE
SOUTH
PERMANENT
MAGNET
NORTH
1 2 3 4
* In application, the terms “gear” and “target” are often inter­changed. However, “gear” is preferred when motion is trans­ferred.
Dwg. MH-016-4
Internal electronics. The ATS622LSB is a self- calibrating sensor 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 sensor. This feature allows air-gap-independent operational characteristics.
1000
800
600
400
200
0
-200
-400
-600
-800
DIFFERENTIAL MAGNETIC FIELD IN GAUSS
-1000
RELATIVE TARGET POSITION
AG = 2.75 mm
0.25 mm INTERVALS AG = 0.25 mm
Dwg. GH-061-2
Magnetic signal before gain control
1000
800
600
400
200
0
-200
-400
ELECTRICAL SIGNAL IN mV
-600
-800
-1000
RELATIVE TARGET POSITION
AG = 2.75 mm AG = 0.25 mm
Dwg. GH-061-3
Magnetic signal after gain control
6
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
Page 7
GEAR-TOOTH SENSOR
DEVICE DESCRIPTION — Continued
ATS622LSB
TRUE ZERO-SPEED,
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 zero- speed detecting gear-tooth sensor subassembly uses a differential Hall-element configuration. This configuration is superior in most applications to a classical single­element 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 sensors 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 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-sensor 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 (p
valley depth (h
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.
- T) > 2 mm;
C
) > 2 mm;
t
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Page 8
ATS622LSB
TRUE ZERO-SPEED, GEAR-TOOTH SENSOR
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 (V
CC(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 sensor.
Output. The output of the subassembly 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.
Output polarity. The output of the device will switch from off to on as the leading edge of the target passes the subassembly 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 subassembly, which means that the output voltage will be low when the unit is facing a tooth.
1
2
3
4
Dwg. AH-006-1
APPLICATIONS INFORMATION
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 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.
4
3
2
1
Dwg. AH-007
8
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
Page 9
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR
APPLICATIONS INFORMATION — Continued
ATS622LSB
Recommended evaluation technique. The self-
calibrating feature of the ATS622LSB requires that a
special evaluation technique be used to measure its high-
accuracy performance capabilities. Installation inaccura-
cies 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.
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.
2.2
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 subassembly. 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 subassembly. 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 4 mm, a performance improve­ment can be observed by rotating the front face of the sensor subassembly. This sensor rotation decreases the effective sensor-to-sensor 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.
α
2.2 COS
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A
TARGET FACE WIDTH, F
>2.2 SIN
α
α
A
Dwg. MH-018-5 mm
9
Page 10
ATS622LSB
TRUE ZERO-SPEED, GEAR-TOOTH SENSOR
APPLICATIONS INFORMATION — Continued
Signal timing accuracy. The magnetic field profile
width is defined by the sensor 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 100 mm 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 sensors 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
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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.
Test Method and Samples
Qualification Test Test Conditions Test Length Per Lot Comments
Temperature Humidity JESD22-A101, 1000 hrs 48 Device biased for Bias Life TA = 85°C, RH = 85% minimum power
Bias Life JESD22-A108, 1000 hrs 48
TA = 150°C, TJ = 165°C
(Surge Operating Life) JESD22-A108, 168 hrs 48
TA = 175°C, TJ = 190°C
Autoclave, Unbiased JESD22-A102, 96 hrs 48
TA = 121°C, 15 psig
High-Temperature JESD22-A103, 1000 hrs 48 (Bake) Storage Life TA = 170°C
Temperature Cycle JESD22-A104 1000 cycles 60 -55°C to +150°C
ESD, CDF-AEC-Q100-002 Pre/Post 3 per Test to failure Human Body Model Reading test All leads > x kV
10
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
Page 11
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR
MECHANICAL INFORMATION
Component Material Function Units
Sensor Face Thermoset epoxy Maximum temperature 170°C*
Plastic Housing Thermoplastic PBT 264 psi deflection temp. (DTUL) 204°C
66 psi deflection temp. (DTUL) 216°C Approximate melting temperature 225°C
Leads Copper
Lead Finish 90/10 tin/lead solder plate
Lead Pull 8 N
* Temperature excursions to 225°C for 2 minutes or less are permitted. † All industry-accepted soldering techniques are permitted for these subassemblies 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)
(sensor location relative to package center is the design objective)
2.2 mm
Lead cross section (in millimeters)
A
Dwg. MH-018-4 mm
0.48
0.36
0.41
NOM.
0.0076 MIN. PLATING THICKNESS
0.38
NOM.
Dwg. MH-019A mm
0.44
0.35
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11
Page 12
ATS622LSB
TRUE ZERO-SPEED, GEAR-TOOTH SENSOR
DIMENSIONS IN MILLIMETERS
DIA
8.8
7.0
7.0
2.0
3.0
NOM
0.38
1.27
TYP
1 2 3 4
0.41
0.9
Tolerances, unless otherwise specified: 1 place ±0.1 mm, 2 places ±0.05 mm.
3.9
A
8.968.09
Dwg. MH-017-1B mm
12
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
Page 13
ATS622LSB
TRUE ZERO-SPEED,
GEAR-TOOTH SENSOR
ADAPTIVE THRESHOLD SENSORS
SELECTION GUIDE
Part Operating Number Temp. Range Key Applications & Salient Features
ATS610LSA -40°C to +150°C
ATS611LSB -40°C to +150°C Fine-pitch, large air gap, speed sensing – transmission speed, ABS,
ATS612JSB -40°C to +115°C Large/small-tooth speed sensing,
ATS632LSA -40°C to +150°C Large-tooth, gear-position sensing – cam angle
ATS640JSB -40°C to +115°C Small-tooth gear-position sensing for two-wire applications,
Large-tooth, speed sensing – crank angle, cam angle, differential, peak-detecting geartooth sensor (to 20 rpm w/ 0.22 µF)
differential, peak-detecting geartooth sensor (to 20 rpm w/ 0.22 µF)
differential, peak-detecting geartooth sensor (to 20 rpm w/ 0.22 µF)
zero speed
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