ATS636LSE - Allegro MicroSystems, Inc.

Programmable Back Biased Hall-Effect

Switch with TPOS Functionality

PACKAGE DIAGRAM

Pin 1 = VCC

Pin2=VOUT

Pin3=NoConnect

Pin 4 = GND

The ATS635LSE and ATS636LSE programmable, true power-on state

(TPOS), sensors are an optimized Hall-effect IC and magnet combination

that switch in response to magnetic signals created by ferrous targets in

gear-tooth sensing and proximity applications.

The devices are externally programmable. A wide range of

programmability is available on the magnetic operate point (BOP) while the

hysteresis remains fixed. This advanced feature allows for optimization of

the sensor switch point and can drastically reduce the effects of

mechanical placement tolerances found in production environments .

A proprietary dynamic offset cancellation technique, with an internal

high-frequency clock, reduces the residual offset voltage, which is normally

caused by device overmolding, temperature dependencies, and thermal

stress. Having the Hall element and amplifier in a single chip minimizes

many problems normally associated with low-level analog signals.

This sensor system is ideal for use in gathering speed or position

information using gear-tooth-based configurations, or for proximity sensing

with ferrous targets.

The ATS635LSE switches HIGH in the presence of a ferrous target or

tooth and switches LOW in the presence of a target valley, window, or

when the ferrous target is removed. The ATS636LSE has the opposite

polarity and switches LOW in the presence of a ferrous target or tooth and

switches HIGH in the presence of a target valley, window, or when the

ferrous target is removed.

ABSOLUTE MAXIMUM RATINGS

Supply Voltage, VCC………………….…….. 28 V*

Reverse Supply Voltage, VRCC…………… -18 V

Overvoltage Supply Current, ICC…..……100 mA

Output Off Voltage, VOUT…………………… 26.5V

Output Sink Current, IOUT…...…………. 20 mA

†

Magnetic Flux Density, B…………… Unlimited

Package Power Dissipation, PD….. See Graph

Operating Temperature Range, TA

Suffix “L”………...……….. -40°Cto+150°C

Junction Temperature, TJ……..…………..165 °C

Storage Temperature Range

TS………………………… -65°Cto+170°C

*Fault conditions that produce supply voltage transients will

be clamped by an internal Zener diode. These conditions

can be tolerated but should be avoided.

†Internal current limiting is intended to protect the device

from output short circuits, but is not intended for continuous

operation.

FEATURES

Chopper Stabilization

 Extremely low switch-point drift over temperature

 On-chip Protection

 Supply transient protection

 Output short-circuit protection

 Reverse-battery protection

True Zero-Speed Operation

 True Power-On State

 Single-chip Sensing IC for High Reliability

 Optimized Magnetic Circuit

 Wide Operating Voltage Range

 Internal Regulator

These devices are available in lead (Pb) free versions, with 100%

matte tin leadframe plating.

ATS635LSE and ATS636LSE

ATS635LSE-DS Worcester, Massachusetts 01615-0036 (508) 853-5000

115 Northeast Cutoff, Box 15036

www.allegromicro.com

Allegro MicroSystems, Inc.

Use the following complete part numbers when ordering:

Part Number Pb-Free Output

(Tooth)

Packing*

ATS635LSETN-T Yes High 13-in. reel, 450 pieces/reel

ATS636LSETN-T Yes Low 13-in. reel, 450 pieces/reel

*Contact Allegro for additional packing options.

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

Page 2 of 15

115 Northeast Cutoff, Box 15036

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

CHARACTERISTICS

ELECTRICAL CHARACTERISTICS over operating voltage and junction temperature range

(unless otherwise noted)

Limits

Characteristics Symbol Test Conditions

Min. Typ. Max. Units

Supply Voltage1 VCC Operating 4.2 – 24 V

After programming

VCC = 0 à VCC(min), t > tON :

B < BOP ATS636

HIGH HIGH HIGH –

Power-Up State POS

B < BOP ATS635 LOW LOW LOW –

Low Output Voltage VOUT(SAT) Output on, IOUT = 20 mA – 175 400 mV

Output Current Limit2 IOUTM Pulse test method

Output on 30 50 90 mA

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

Output off (HIGH) – 2.5 5.5 mA

Supply Current ICC Output on (LOW) – 2.5 5.5 mA

Reverse Supply Current IRCC VRCC = -18V – – -5 mA

Power-On Delay 3 tON Output off; VCC > VCC(min) – 35 50 µs

Output Rise Time tr RL = 820 Ω, CL = 10 pF – 1.2 5 µs

Output Fall Time tf RL = 820 Ω, CL = 10 pF – 1.2 5 µs

Sampling Frequency fSample - – 250 - kHz

Supply Zener Voltage VZsupply ICC = ICC(max) + 3 mA

TA = 25°C 28 – – V

Output Zener Voltage VZOutput IOUT = 3 mA

TA = 25°C 30 – – V

Supply Zener Current 4 IZsupply VS = 28 V – – 8.5 mA

Output Zener Current IZOutput VO = 30 V – – 3 mA

Note: Typical data is at VCC = 12 V and TA = +25°C.

1 Do not exceed the maximum thermal junction temperature: see power de-rating curve.

2 Short circuit protection is not intended for continuous operation and is tested using pulses.

3 The power on delay is the time that is necessary before the output signal is valid

4 The maximum spec limit for this parameter is equivalent to ICC(max)

+ 3 mA

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

115 Northeast Cutoff, Box 15036

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

MAGNETIC CHARACTERISTICS over operating voltage and junction temperature range using

reference target (Unless otherwise noted)

Limits

Characteristics Symbol Test Conditions Min. Typ. Max. Units

Switch Point – 7 – Bit

Switch Point Polarity – 1 – Bit

Number of Programming

Bits -

Programming Lock – 1 – Bit

Gear Tooth Sensor / Proximity Sensing Characteristics (Low Switchpoint Only)

Temp: 25°C Code –127 2.5 – – mm

1Programming Air Gap

Range AGRange Temp: 25°C Code +127 – – 1.5 mm

Programming Resolution AGRes Temperature: 25°C

Program Air Gap = 2.5 mm – 0.05 – mm

2Air Gap Drift Over Full

Temperature Range AGDrift Device Programmed

to 2.5 mm – 0.2 – mm

Over Tooth (ATS635LSE) – HIGH – –

Over Valley (ATS635LSE) – LOW – –

Over Tooth (ATS636LSE) – LOW – –

Polarity P

Over Valley (ATS636LSE) – HIGH – –

1 The switch point will vary over temperature. A sufficient margin obtained through customer testing is required to guarantee functionality over

temperature. Programming at larger air gaps leaves no safety margin for switchpoint drift. See the applications note: “Proximity Sensing

Programming Technique” http://www.allegromicro.com/techpub2/proximity_sensing/ or visit the Allegro website at http://www.allegromicro.com

for additional information.

2 The switch point will vary over temperature, proportionally to the programmed air gap. This parameter is based on characterization data and is not

a tested parameter in production. Switch point air gap generally drifts downward as temperature increases.

Tooth and Valley Field vs. Air Gap

Reference Target

200

400

600

800

1000

1200

1400

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

Air Gap [mm]

Flux Density [Gauss]

Reference Target Tooth

Reference Target Valley

Reference Target Tooth and Valley Field vs. Air Gap

Reference Target Flux Density vs. Position

200

400

600

800

1000

1200

1400

0 30 60 90 120 150 180 210 240 270 300 330 360

Position (º)

Flux Density (Gauss)

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

Reference Target Flux Density vs. Position: Typical

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

115 Northeast Cutoff, Box 15036

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

REFERENCE TARGET DIMENSIONS

Target Outside

Diameter

(Do)

Face Width

(F)

Circular Tooth

Length

(T)

Circular Valley

Length

(PC – T)

Tooth Whole

Depth

(ht)

Reference Target 120mm 6mm 23.5mm 23.5mm 5mm

GEAR PARAMETERS FOR CORRECT OPERATION Limits

Characteristic Description Min. Typ. Max. Units

Tooth Whole Depth (ht) Depth of Target Valley 5 – – mm

Circular Valley Length (PC – T) Length of Target Valley 13 – – mm

Circular Tooth Length (T) Length of Target Tooth 5 – – mm

Face Width (F) Thickness or Width of Target Tooth 5 – – mm

MATERIAL: CRS 1018

Reference Target

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

115 Northeast Cutoff, Box 15036

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

ELECTROMAGNETC CAPABILITY (EMC) PERFORMANCE

Please contact Allegro MicroSystems for EMC performance

Test Name Reference Specification

ESD – Human Body Model AEC-Q100-002

ESD – Machine Model AEC-Q100-003

Conducted Transients ISO 7637-1

Direct RF Injection ISO 11452-7

Bulk Current Injection ISO 11452-4

TEM Cell ISO 11452-3

FUNCTIONAL BLOCK DIAGRAM

Reg

Clock/Logic

AMP S/H LPF Current

Limit

VCC

OUT

GND

Programmming

Logic

Program / Lock

Offset Adjust

To all

subcircuits

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

115 Northeast Cutoff, Box 15036

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

Regulator

Amplifier Sample/

Hold

CLOCK

Hall Element

FUNCTIONAL DESCRIPTION

Chopper-Stabilized Technique . The basic Hall sensor

is a small sheet of semiconductor material in which a

constant bias current will flow when a constant voltage

source is applied. The output will take the form of a

voltage measured across the width of the sheet and will

have negligible value in the absence of a magnetic field.

When a magnetic field with flux lines at right angles to

the Hall current is applied, a small signal voltage directly

proportional to the strength of the magnetic field will

occur at the output terminals.

This signal voltage is proportionally small relative to the

offset produced at the input of the chip. This makes it

very difficult to process the signal and maintain an

accurate, reliable output over the specified temperature

and voltage range. Therefore, it is important to reduce

any offset on the signal that could be amplified when the

signal is processed.

Chopper Stabilization is a unique approach used to

minimize input offset on the chip. This technique

removes a key source of output drift with temperature

and stress, and produces a 3X reduction in offset over

other conventional methods.

This offset reduction Chopping Technique is based on a

signal modulation-demodulation process. The undesired

offset signal is separated from the magnetically induced

signal in the frequency domain. The offset (and any low

frequency noise) component of the signal can be seen

as signal corruption added after the signal modulation

process has taken place. Therefore, the DC offset is not

modulated and remains a low frequency component.

Consequently, the signal demodulation process acts as

a modulation process for the offset causing the

magnetically induced signal to recover its original

spectrum at baseband while the DC offset becomes a

high frequency signal. Then, using a low pass filter the

signal passes while the modulated DC offset is

suppressed.

The advantage of this approach is significant offset

reduction, which de-sensitizes the chip against the

effects of temperature and stress. The disadvantage is

that this technique features a demodulator that uses a

sample and hold block to store and recover the signal.

This sampling process can slightly degrade the Signal-

to-Noise Ratio (SNR) by producing replicas of the noise

spectrum at the baseband. The degradation is a

function of the ratio between the white noise spectrum

and the sampling frequency. The effect of the

degradation of the SNR is higher jitter, a.k.a. signal

repeatability. In comparison to a continuous time device,

the jitter spec can be increased by a factor of five.

Figure 1 – Concept of Chopper-Stabilization Algorithm

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

Page 7 of 15

115 Northeast Cutoff, Box 15036

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

FUNCTION DESCRIPTION: ADDRESSING / PROGRAMMING PROTOCOL

The ATS635LSE and ATS636LSE magnetic operate point (BOP) is programmed by serially addressing the devices

through the supply terminal (1). After the correct operate point is determined, the device programming bits are selected

and blown, then a lock bit is selected and blown to prevent any further (accidental) programming.

Addressing: Bop is programmable in both the positive and negative direction from its initial value. Addressing is used to

determine the desired code, while programming is used to lock the code. A unique key is needed to blow fuses, while

addressing as described below does not allow for the device to be programmed accidentally.

Addressing with positive polarity. The magnetic operate point (BOP) is adjustable using 7 bits or 128 addresses. The

Addresses are sequentially selected (Figure 2) until the required operate point is reached. The first address must be

selected with a High voltage pulse (VPP), while the remaining pulses should be V

PH Pulses. Note that the difference

between BOP and the magnetic release point (BRP), the Hysteresis (BHYS), is fixed for all addresses.

td(1) td(0)

Code 1

Code 2

Code 3

Code N-2

Code N-1

Code N

(Up to 127)

Figure 2 – Addressing Pulses: Positive Polarity

Addressing with negative polarity. The magnetic operate point (BOP) is adjustable with negative polarity using 7 bits or

128 addresses. To invert the polarity it is necessary to first apply a keying sequence (Figure 3). Th e polarity key contains

a V

PP pulse and at least 1 V

PH pulse, but no more than 6 V

PH pulses; the key in Figure 3 shows 2 V

PH pulses. The

addresses are then sequentially selected until the required operate point is reached. The first address must be selected

with a High voltage pulse (VPP), while the remaining pulses should be VPH Pulses.

td(1) td(0)

Code -1

Code -2

Code -3

Code -(N-2)

Code -(N-1)

Code -N

(Up to -127)

Polarity

Key

Figure 3 – Addressing Pulses: Negative Polarity

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

Page 8 of 15

115 Northeast Cutoff, Box 15036

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

Program Enable. To program the device, a keying sequence is used to activate / enable the programming mode as

shown in Figure 4. This program key sequence consisting of a VPP pulse, at least seven VPH pulses, and a VPP pulse with

no supply interruptions. The sequence is designed to prevent the device from being programmed accidentally (e.g., as a

result of noise on the supply line).

td(1) td(1) td(0)

PROGRAM ENABLE

7 or More Pulses

(8 Pulses Shown)

VPL

VPH

VPP

Figure 4 – Program Enable Pulse Sequence

Code Programming. After the desired switch point code is selected (0 through 127), each bit of the corresponding binary

address should be programmed individually, not at the same time. For example, to program code 5 (binary 000101), bits

1 and 3 need to be programmed. A bit is programmed by addressing the code and then applying a V

PP pulse, the

programming is not reversible. An appropriate sequence for blowing code 5 is shown in Figure 5.

Figure 5 – Code Programming Example

Polarity Bit Programming. If the desired switchpoint has negative polarity, the polarity bit must be programmed. To do

this it is necessary to first apply the polarity key sequence before the program key sequence (Figure 6). Finally a VPP

pulse of duration tdP must be applied to program this bit, the programming is not reversible. The polarity bit is for adjusting

programming range only and will not affect the output polarity. The proper output polarity device is determined by

ordering the correct part number (ATS635 or ATS636), as they are different ICs.

Program Enable

td(1) td(1) td(0) tdP

Polarity

Key

Polarity Bit

Program

Figure 6 – Polarity Bit Programming

Program Enable

Bit 1 Address

Bit 1 Program

Bit 3 Address

000100

Code 4

Bit 3 Program

Program Enable

td(1) td(1) td(0) tdP

000001

Code 1

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

Page 9 of 15

115 Northeast Cutoff, Box 15036

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

Lock-Bit Programming. After the desired code is programmed, the lock bit (code 128), can be programmed (figure 7) to

prevent further programming of the device. Again; programming is not reversible.

Figure 7 – Lock-Bit Programming Pulse Sequence

See Allegro website at http://www.allegromicro.com for extensive information on device programming as well as

programming products. Programming hardware is available for purchase and programming software is available for free.

Valid over operating temperature range unless otherwise noted.

Limits

Part Number Characteristics Symbol Test Conditions Min. Typ. Max. Units

PROGRAMMING PROTOCOL (TA = +25°C)

VPL Minimum voltage range

during programming 4.5 5 5.5 V

VPH 8.5 – 15 V

5,6Programming Voltage

VPP 25 – 27 V

Programming Current IPP Maximum supply current

during programming – 500 – mA

td(0) OFF time between bits 20 – – µs

td(1) Enable, address, program,

or lock bit ON time 20 – – µs Pulsewidth

tdP Program pulse ON time 100 300 – µs

Pulse Rise Time tr VPL to VPH or VPP – – 11 µs

ATS635 /

ATS636

Pulse Fall Time tf VPH or VPP to VPL – – 5 µs

5 Programming Voltages are measured at Pin 1 (VCC) of SIP. A minimum capacitance of 0.1 µF must be connected from VCC to GND

of the SIP to provide the current necessary to blow the fuse.

6 Testing is the only method that guarantees successful programming.

Program Enable

td(1) td(1) td(0) tdP

Lock Bit

Address

128 Pulses

Lock Bit

Program

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

115 Northeast Cutoff, Box 15036

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

FUNCTIONAL DESCRIPTION (CONT.): TYPICAL APPLICATION CIRCUIT

Applications. It is strongly recommended that an external ceramic bypass capacitor in the range of 0.01 µF to 0.1 µF be

connected between the supply and ground of the device to reduce both external noise and noise generated by the

chopper-stabilization technique. (The diagram below shows a 0.1 µF bypass capacitor.)

The series resistor R

S in combination with the bypass capacitor creates a filter for EMC pulses. The series resistor will

have a drop of approximately 800 mV, this must be considered for the minimum VCC requirement of the ATS635LSE /

ATS636LSE. The small capacitor on the output of the device improves the EMC performance of the device.

The pull-up resistor should be chosen to limit the current through the output transistor; do not exceed the maximum

continuous output current of the device.

Note: This circuit cannot be used to program the device, as the series resistance is too large, and a minimum capacitance

of 0.1 µF must be connected from VCC to GND of the SIP to provide the current necessary to blow the fuse.

Typical Application:

1.2k Ohm

Supply

VCC

100 Ohm

GND

0.1 µF

VOUT

ATS635/636

120 pF

Extensive applications information on magnets and Hall-effect sensors including Chopper-Stabilization is available in the

Allegro Electronic Data Book CD, or at the website: http://www.allegromicro.com .

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

Page 11 of 15

115 Northeast Cutoff, Box 15036

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

CHARACTERISTIC DATA

Data taken from 3 lots, 30 pieces/lot

Reference Target 8x

ICC ON

-50 -25 025 50 75 100 125 150 175

TEMPERATURE (°C)

ICC (mA)

15V

24V

ICC OFF

-50 -25 025 50 75 100 125 150 175

TEMPERATURE (°C)

ICC (mA)

15V

24V

VSAT

100

200

300

400

500

-50 -25 0 25 50 75 100 125 150 175

TEMPERATURE (°C)

VSAT (mV)

20mA

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

Page 12 of 15

115 Northeast Cutoff, Box 15036

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

CHARACTERISTIC DATA (continued)

Data taken from 3 lots, 30 pieces/lot

Reference Target 8x

Notes:

s Air gaps for Code 127 @ 150°C are interpolated due to test limitations at minimum air gap.

s These graphs are intended to provide an understanding of how the program codes affect the switch points. In a

production environment, individual devices would be programmed to individual codes to ensure all devices switch at

the same air gap.

BOP/BRP vs. Program Code

-50 0 50 100 150 200

TEMPERATURE (°C)

AIR GAP (mm)

Code -8 BOP

Code -8 BRP

Code 0 BOP

Code 0 BRP

Code +32 BOP

Code +32 BRP

Code +127 BOP

Code +127 BRP

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

Page 13 of 15

115 Northeast Cutoff, Box 15036

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

POWER DE-RATING – SE Package

Power De -Rating

Due to internal power consumption, the temperature of the

IC (junction temperature, 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:

∆T=PD × RθJA

Where PD = V

CC × ICC

∴ ∆T = V

CC × ICC × RθJA

Where ∆T denotes the temperature rise resulting from the

IC’s power dissipation:

TJ = TA + ∆T RθJA = 77°C/W TJ(max) = 165°C

Typical T J Calculation:

TA = 25°C, V

CC = 5 V, ICC(on) = 5.5 mA

PD = V

CC × ICC

PD = 5 V × 5.5 mA = 27.5 mW

∆T = PD × RθJA = 27.5 mW × 77°C/W = 2.0°

TJ = TA + ∆T = 25°C + 2.0°C = 27.0°C

Maximum Allowable Power Dissipation Calculation

TJ = TA + ∆T

TJ(max) = 165°C, if TA = 150°C then:

165 = 150 + ∆T

∆T = 15°C

DT = PD× RθJA (RθJA = 77°C/W)

\ PD(max) = 15°C / 77°C/W = 1 95 mW @ TA = 150°C

Maximum V CC for PD(max) =111 mW at T A=150°C

PD = V

CC × ICC ICC = 10mA (max) at 150°C

VCC = PD / ICC = 195 mW / 5.5 mA = 35.4 V

500

1000

1500

2000

2500

3000

3500

4000

4500

20 40 60 80 100 120 140 160 180

Temperature (°C)

Power Dissipation, P

(mW)

Power Dissipation versus Ambient Temperature

(RθJA = 77 ºC/W)

2-layer PCB

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

Page 14 of 15

115 Northeast Cutoff, Box 15036

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

SE PACKAGE DIMENSIONS

Reference Dimensions Only

1.27 .050

1.08 .043

10 .394

7 .276

0.38 .015

6.2 .244

20.95 .825

11.6 .457

4.9 .193

3.3 .130

1.3 .051

2 .079

0.6 .240

2431

Dambar removal protrusion (16X)

Metallic protrusion, electrically connected to pin 4 and substrate (both sides)

Active Area Depth, 0.43 mm [.017]

Thermoplastic Molded Lead Bar for alignment during shipment

EHall element (not to scale)

Preliminary dimensions, for reference only

Untoleranced dimensions are nominal.

Dimensions in millimeters

U.S. Customary dimensions (in.) in brackets, for reference only

Dimensions exclusive of mold flash, burrs, and dambar protrusions

Exact case and lead configuration at supplier discretion within limits shown

ATS635LSE and ATS636LSE

PROGRAMMABLE TRUE POWER-ON HALL-EFFECT GEAR-TOOTH SWITCHES

Page 15 of 15

115 Northeast Cutoff, Box 15036

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

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; 5,719,130; 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 design 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 applications, 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 which may result from its use.