ATS632LSC - Allegro MicroSystems, Inc.

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

Always order by complete part number, e.g., ATS632LSC .

ZERO-SPEED, SELF-CALIBRATING,

NON-ORIENTED, HALL-EFFECT GEAR-TOOTH SENSOR

Data Sheet

27627.126

The ATS632LSC gear-tooth sensor is an optimized Hall-effect IC/

magnet combination that provides tooth/valley recognition and ex-

tremely accurate tooth edge detection when used with large-pitch

targets. The sensor subassembly consists of a high-temperature

plastic shell that holds together a compound samarium-cobalt magnet,

a single-element self-calibrating Hall-effect IC that has been optimized

to the magnetic circuit, and a voltage regulator. This small package,

with its non-oriented operation, can be easily assembled and used in

conjunction with a number of gear configurations.

The gear sensing technology used for this sensor subassembly 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.

The sensor system is ideal for use in gathering speed, position and

profile information of ferrous objects. The device is 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 ATS611LSB is recommended.

ABSOLUTE MAXIMUM RATINGS

Supply Voltage, VCC ......................... 24 V

Reverse Supply Voltage,

VRCC (1 minute max.)................ -24 V

Output OFF Voltage, VOUT................ 24 V

Output Current, IOUT .. Internally Limited

Reverse Output Current, IOUT ........ 50 mA

Package Power Dissipation,

PD.................................... See Graph

Operating Temperature Range,

TA........................... -40°C to +150°C

Storage Temperature, TS............ +170°C

ATS632LSC

continued next page…

Dwg. AH-008

123

1 = Supply

2 = Output

3 = Ground

PRELIMINARY INFORMATION

(subject to change without notice)

April 8, 1998

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

FEATURES AND BENEFITS

■Non-Oriented Installation

■Fully Optimized Gear-Tooth Sensors

■Single-Chip Sensing IC for High Reliability

■Zero-Speed Digital Output Representing Target

Profile

■Extremely Low Timing Accuracy Drift with Tempera-

ture

■Large Operating Air Gaps

■Optimized Magnetic Circuit

■Self-Calibrating Circuitry

with Integrated Offset Cancellation

6-bit A/D Converters to Capture Peaks

Thresholds Proportional to Peak-to-Peak Signals

FUNCTIONAL BLOCK DIAGRAM

600

400

200

40 80 120 160

AMBIENT TEMPERATURE IN °C

ALLOWABLE PACKAGE POWER DISSIPATION IN mW

Dwg. GH-065-2

60 100 140 18020

800

1200

RθJA = 119°C/W

1000

REG

SUPPLY

MAGNET

REFERENCE

GENERATOR

THRESHOLD

PEAK

CURRENT

LIMIT

NEGATIVE PEAK

TRACK & HOLD

POSITIVE PEAK

TRACK & HOLD

OUTPUT

LOGIC

OUTPUT

GROUND

Dwg. FH-015-3

–

GAIN

OFFSET

330 pF

100 Ω

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

Limits

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Supply Voltage VCC Operating, TJ < 165°C 6.0 12 24 V

Under-Voltage Lockout VCC(UV) IOUT = 5 mA, VCC = 0 → 6 V – 5.0 – V

Low Output Voltage VOUT(L) IOUT = 5 mA, Output ON – 0.7 1.6 V

Output Current Limit IOUTM VOUT = 12 V 25 45 55 mA

Output Leakage Current IOFF VOUT = 24 V, Output OFF – 5.0 10 µA

Supply Current ICC Output OFF, Target Speed = 0 RPM – 9.0 15 mA

Calibration Count ncal Output falling mechanical edges 16 16 16 Pulses

after power on for startup calibration

to be complete

Calibration Update nup Output falling mechanical edges 64 64 64 Pulses

for the threshold calibration to be

complete

Power-On Time tpo VCC > 6 V – 200 500 µs

Output Rise Time trRL = 2.5 kΩ, CL = 10 pF – 3.0 6.0 µs

Output Fall Time tfRL = 2.5 kΩ, CL = 10 pF – 1.0 3.0 µs

ELECTRICAL CHARACTERISTICS over operating voltage and temperature range (unless

otherwise specified).

NOTE: Typical data is at VCC = 12 V and TA = +25°C and is for design information only.

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

Limits

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Operating Air Gap Range AG Operating, 0.3 – 1.9 mm

Target Speed > 20 RPM

Output Polarity – Operating, Over Tooth Low Low Low –

Operating, Over Valley High High High –

Timing Accuracy tθTarget Speed < 3500 RPM, – ±0.25 ±0.50 °

0.3 mm ≤ AG ≤ 1.9 mm

OPERATION over operating voltage and temperature range with reference target (unless oth-

erwise specified).

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 – Timing accuracy may change – – ±0.25 mm

TARGET DESIGN CRITERIA

Diameter Thickness Tooth Width Valley Width Valley Depth

Type (Do) (F) (T) (PC - T) (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

TARGET DIMENSIONS

NOTE: Timing accuracy data is taken by recalibrating the unit at each air gap.

NOTE: Air Gap is defined as the distance from the face of the sensor subassembly to the target.

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

continued next page…

TYPICAL OPERATING CHARACTERISTICS

3.0

0 1.0 1.75

AIR GAP IN MILLIMETERS

RELATIVE TIMING ACCURACY IN DEGREES

Dwg. GH-063-4

0.5 1.5

2.0

1.0

-2.0

-3.0

-1.0

0.25 0.75 1.25

RISING EDGE

-40°C

+25°C

+150°C

TARGET #1

3.0

0 1.0 1.75

AIR GAP IN MILLIMETERS

Dwg. GH-063-5

0.5 1.5

2.0

1.0

-2.0

-3.0

-1.0

0.25 0.75 1.25

FALLING EDGE

-40°C

+25°C

+150°C

TARGET #1

RELATIVE TIMING ACCURACY IN DEGREES

3.0

0 1.0 1.75

AIR GAP IN MILLIMETERS

Dwg. GH-063-6

0.5 1.5

2.0

1.0

-2.0

-3.0

-1.0

0.25 0.75 1.25

RISING EDGE

-40°C

+25°C

+150°C

TARGET #2

RELATIVE TIMING ACCURACY IN DEGREES

3.0

0 1.0 1.75

AIR GAP IN MILLIMETERS

Dwg. GH-063-7

0.5 1.5

2.0

1.0

-2.0

-3.0

-1.0

0.25 0.75 1.25

FALLING EDGE

-40°C

+25°C

+150°C

TARGET #2

RELATIVE TIMING ACCURACY IN DEGREES

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

TYPICAL OPERATING CHARACTERISTICS — Continued

51.0

49.5

0 1.0 1.75

AIR GAP IN MILLIMETERS

DUTY CYCLE IN PER CENT

Dwg. GH-008-11

0.5 1.5

50.5

50.0

48.5

48.0

49.0

0.25 0.75 1.25

-40°C

+25°C

+150°C

TARGET #1

-1

1000 3000 5000 70002000 4000 6000

-3

REFERENCE TARGET SPEED IN RPM

RELATIVE TIMING ACCURACY IN DEGREES

Dwg. GH-064-3

-2

RISING EDGE

0.5 mm

1.0 mm

1.5 mm

2.0 mm

AIR GAPS

51.0

49.5

0 1.0 1.75

AIR GAP IN MILLIMETERS

DUTY CYCLE IN PER CENT

Dwg. GH-008-12

0.5 1.5

50.5

50.0

48.5

48.0

49.0

-40°C

+25°C

+150°C

0.25 0.75 1.25

TARGET #2

-1

1000 3000 5000 70002000 4000 6000

-3

REFERENCE TARGET SPEED IN RPM

RELATIVE TIMING ACCURACY IN DEGREES

Dwg. GH-064-4

-2

FALLING EDGE

0.5 mm

1.0 mm

1.5 mm

2.0 mm

AIR GAPS

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

APPLICATIONS INFORMATION

Recommended Evaluation Technique. The self-

calibrating feature of the ATS632LSC 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 re-powered at each air gap

when gathering timing accuracy data.

Self-Calibrating Functions. This subassembly is

designed to minimize performance variation caused by

the large air gap variations resulting from installation by

self-calibrating at power-on. It is also designed to mini-

mize performance variation caused by the smaller, slower

air gap changes resulting from temperature change and

gear run-out during continuous operation by 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.

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 48 -55°C to +150°C

ESD, CDF-AEC-Q100-002 Pre/Post 3 per Test to failure

Human Body Model Reading test All leads > 8 kV

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

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 subassembly. 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

subassembly. Wait for 64 output pulses to occur.

Monitor the output for correct switching and measure

accuracy.

Device Switch Points. The device switch points are

referenced to the peak-to-peak values of the gain-ad-

justed 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.

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 mini-

mum 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-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.

APPLICATIONS INFORMATION — Continued

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.

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. The output of the subassembly is a short-circuit-

protected 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 either at the sensor

module or at the controller.

Output Polarity. The switching of the output is independent

of the direction of gear rotation.

Power Supply Protection. These devices require

minimal protection circuitry during operation from a low-

voltage line. The internal voltage regulator provides

immunity to power supply variations between 6 V and

24 V. EMI/RFI protection is provided as part of the

internal regulator. In extremely noisy environments,

additional (external) components may be required.

Additional applications Information on gear-tooth and

other Hall-effect sensors is provided in the

Allegro Inte-

grated and Discrete Semiconductors Data Book

Application Note 27701

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

continued next page…

Sensor Location (in millimeters)

(sensor location relative to package center is the design

objective)

MECHANICAL INFORMATION

† 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.

Component Material Function Units

Package Polyamide 6/12, 264 psi deflection temp. (DTUL) 200°C

33% glass filled Approximate melting temperature 219°C

Circuit Board High-temperature FR-4 Glass transition temperature 170°C

Terminals 1 oz Copper – –

Terminal Finish 63/37 tin/lead solder plate – †

Flame Class Rating – – UL94V-0

Dwg. MH-021 mm

0.1

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

DIMENSIONS IN MILLIMETERS

Tolerances unless otherwise specified: 1 place ±0.1 mm, 2 places ±0.05 mm.

Dwg. MH-020 mm

5.0

1.5

TYP

1.0

TYP

6.0

4.9

10.0

MAX

5.06.6

11.0

0.8

27.5

GATE

PROTRUSION

0.3

MAX

1.0

PLATED THRU

TYP

ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

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ATS632LSC

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

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 design of its products.

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.

ADAPTIVE THRESHOLD SENSORS

SELECTION GUIDE

Part Number Application

ATS535CSB Programmable, TPOS, large-tooth gear-position or proximity sensing (commercial temp. range)

ATS535JSB

Programmable, TPOS, large-tooth gear-position or proximity sensing (industrial/auto. temp. range)

ATS610LSA Large-tooth, gear-position sensing – crank angle, cam angle

ATS610LSC Large-tooth, gear-position sensing

with internal voltage regulator – crank angle, cam angle

ATS611LSB Fine-pitch, large air gap, gear speed sensing – transmission speed, ABS

ATS612JSB Large/small-tooth gear-position sensing – crank angle, transmission speed,

cam angle

ATS632LSA Large-tooth, gear-position sensing (LOW digital output state over a tooth),

cam angle

ATS632LSC Large-tooth, gear-position sensing (LOW digital output state over a tooth),

with internal voltage regulator – cam angle

ATS640JSB TPOS, gear-position sensing for two-wire applications