A3197LLT - Allegro MicroSystems, Inc.

Always order by complete part number, e.g., A3197LU .

3197

PROTECTED, HIGH-TEMPERATURE,

OPEN-COLLECTOR HALL-EFFECT LATCH

These open-collector Hall-effect latches are capable of sensing magnetic

fields while using an unprotected power supply. The A3197LLT and A3197LU

can provide position and speed information by providing a digital output for

magnetic fields that exceed their predefined switch points. These devices

operate down to zero speed and have switch points that are designed to be

extremely stable over a wide operating temperature and voltage range. The

latching characteristics make them ideal for use in pulse counting applications

when used with a multi-pole ring magnet. Thermal and output short-circuit

protection allow an increased wiring harness fault tolerance. The temperature

compensated switch points, the wide operating voltage range, and the integrated

protection make these devices ideal for use in automotive applications such as

transmission speed sensors and integrated wheel bearing speed sensors.

Each monolithic device contains an integrated Hall-effect transducer, a

temperature-compensated comparator, a voltage regulator, and a buffered 35 mA

output sink stage. Supply protection is made possible by the integration of

overvoltage and undervoltage shutdown circuitry that monitor supply fault

conditions and shut down the IC. Noise shutdown circuitry (patent applied for)

prevents the propagation of supply transients to the logic load. Output protec-

tion circuitry includes a current limit loop that limits the maximum output sink

current, and thermal protection circuitry that shuts down the device during an

over-heating condition such as with a shorted load.

The A3197LLT and A3197LU are rated for operation over an extended

temperature range of -40°C to +150°C. They are supplied in a three-lead SIP

(suffix ‘U’) or a surface-mount SOT-89 (suffix ‘LT’).

FEATURES

■Internal Protection For Automotive (ISO/DIN) Transients

■Operation From Unregulated Supply

■Reverse Battery Protection

■Undervoltage Lockout

■Supply Noise-Suppression Circuitry

■Output Short-Circuit Protection

■Output Zener Clamp

■Thermal Protection

■Symmetrical Latching Switch Points

■Operable with Multipole Ring Magnets

Data Sheet

27609.10A*

ABSOLUTE MAXIMUM RATINGS

Supply Voltage, VCC

(100 ms) ................................... 115 V*

(continuous) ............................... 28 V*

Reverse Battery Voltage, VRCC

(100 ms) ................................... -100 V

(continuous) ............................... -35 V

Magnetic Flux Density, B .......... Unlimited

Output OFF Voltage, VOUT ................. 26 V

Reverse Output Voltage VOUT ......... -0.5 V

Continuous Output Current,

IOUT .......................................... 35 mA*

Reverse Output Current,

IOUT ........................................ -100 mA

Package Power Dissipation,

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

Junction Temperature, TJ................. 170°C

Operating Temperature Range,

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

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

*Fault condition, internal overvoltage shutdown

above 28 V; output current limited above 35 mA.

Dwg. PH-003-2

SUPPLY

VCC

GROUND

OUTPUT

PTCT

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

115 Northeast Cutoff, Box 15036

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

FUNCTIONAL BLOCK DIAGRAM

REG. OUTPUT

Dwg. FH-012A

GROUND

VCC

<1Ω

POWER UP &

TRANSIENT

PROTECTION

CURRENT

LIMIT

OVERVOLT.

LOCKOUT

THERMAL

SHUTDOWN

CONTROL

600

400

200

700

500

300

100

800

40 80 120 160

AMBIENT TEMPERATURE IN °°

°°C

ALLOWABLE PACKAGE POWER DISSIPATION IN MILLIWATTS

Dwg. GH-054B

Suffix "–U"

θJA

= 183°C/W

60 100 140 18020

Suffix "L–"

Suffix "E–"

Suffix "–LT"

θJA

= 180°C/W

NOTE – Permitted duty cycle will be less than 100%

at maximum ambient temperature with high supply

voltages, i.e., TA ≥ 140°C, VCC ≥ 12 V, and the “LT”

package. The thermal shutdown circuitry does not

protect the device from these stresses (see Internal

Protective Features).

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

www.allegromicro.com

Limits

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Operate Point BOP TA = -40°C 60 130 200 G

TA = +25°C 50 110 160 G

TA = +150°C 40 105 150 G

Release Point BRP TA = -40°C -200 -140 -60 G

TA = +25°C -160 -120 -50 G

TA = +150°C -150 -100 -40 G

Hysteresis Bhys TA = -40°C 150 270 — G

(BOP - BRP)T

A = +25°C 130 230 — G

TA = +150°C 110 205 — G

ELECTRICAL CHARACTERISTICS

over operating voltage and temperature range

(unless otherwise specified).

MAGNETIC CHARACTERISTICS over operating voltage range

(unless otherwise specified).

NOTES:BOP = magnetic operate point (output turns ON); BRP = magnetic release point (output turns OFF).

As used here, negative flux densities are defined as less than zero (algebraic convention).

Typical values are at TA = +25°C and VCC = 12 V (unless otherwise specified).

* Fault condition. Device is shut down and operation is not possible.

Limits

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Supply Voltage VCC Operating (but VCC x ICC vs TA limited) VCC(UV) 12 26 V

Overvoltage Shutdown* VCC(OV) B > BOP 28 — 55 V

Undervoltage Shutdown* VCC(UV) B > BOP 3.7 — 4.5 V

Output Voltage, On VOUT(SAT) B > BOP, IOUT = 30 mA, VCC = 16 V — 0.2 0.5 V

Output Leakage Current IOFF VOUT = 26 V — — 5.0 µA

Output Clamp Voltage VOUT(CLMP) B < BRP, VCC = 115 V*, IOUT = 0 28 32 40 V

Output Current Limit IOUTMAX B > BOP, VOUT = 12 V 355070mA

Supply Current ICC B < BRP, VCC = 24 V, IOUT = 0 — 5.2 9.0 mA

B > BOP, VCC = 24 V, IOUT = 20 mA — 7.8 12 mA

VCC = +115 V* — 8.0 17 mA

Reverse Battery Current* IRCC VRCC = -35 V* — -0.5 -5.0 mA

VRCC = -100 V* — -2.0 -10 mA

Output Rise Time trCL = 20 pF, RL = 330 Ω, VBB = 12 V — 0.05 2.0 µs

Output Fall Time tfCL = 20 pF, RL = 330 Ω, VBB = 12 V — 0.30 5.0 µs

Thermal Shutdown Temp.* TJ165 — 190 °C

Package Thermal Resist. RθJA “LT” Package — 258 — °C/W

“U” Package — 183 — °C/W

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

115 Northeast Cutoff, Box 15036

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

TYPICAL OPERATING CHARACTERISTICS

Output Saturation Voltage

Supply Current

0 25 50 75 100

AMBIENT TEMPERATURE IN °°

°°C

-50

Dwg. GH-052-2

125-25

SWITCH POINTS IN GAUSS

200

100

-100

-200

RELEASE POINT

OPERATE POINT

150

V = 5 V–24 V

Switch Points

4.0

SUPPLY CURRENT IN mA

8.0

7.0

6.0

5.0

0 255075100

AMBIENT TEMPERATURE IN °°

°°C

-50

Dwg. GH-028-3

125-25 150

V = 5 V

B ≥ B

B ≤ B

V = 24 V

0 25 50 75 100

500

AMBIENT TEMPERATURE IN °°

°°C

400

200

-50

Dwg. GH-040-3

SATURATION VOLTAGE IN mV

150

-25 125

I = 30 mA

OUT

300

100

V = 12 V

I = 5 mA

OUT

B ≥ B

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

www.allegromicro.com

26 V

MAX

0+B

OUTPUT VOLTAGE IN VOLTS

FLUX DENSITY Dwg. GH-034-2A

-B

VOUT(SAT)

OPERATION

In operation, the output transistor is OFF

until the strength of the magnetic field

perpendicular to the surface of the chip

exceeds the threshold or operate point (BOP).

When the field strength exceeds BOP, the

output transistor switches ON

(a logic low) and is capable of sinking

35 mA of current.

The output transistor switches OFF (a

logic high) when magnetic field reversal

results in a magnetic flux density below the

OFF threshold (BRP). This is illustrated in

the transfer characteristics graph. Note that

the device latches; that is, a south pole of

sufficient strength will turn the device ON.

Removal of the south pole will leave the

device ON. The presence of a north pole of

sufficient strength is required to turn the

device OFF.

The switch points increase in sensitivity

with increasing temperature to compensate

for the typical ferrite magnet temperature

characteristic. The simplest form of magnet

that will operate these devices is a ring

magnet. Other methods of operation are

possible.

TEST CIRCUIT AND TYPICAL APPLICATION

TO µP

Dwg. EH-006A

CC(UV)

TO 26 V

WITH TRANSIENTS

REGULATED

< 26 V

BYPASS

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

115 Northeast Cutoff, Box 15036

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

Power Supply Transients (Noise);

Overvoltage and Undervoltage Lockout.

Even in protected devices, positive and

negative power supply transients that would

not normally cause physical damage can cause

logic errors in control systems. The A3197LT

and A3197LU include noise suppression

features to prevent this.

In a typical application, where the output

is externally pulled up to a regulated voltage

<28 V, the effects of power supply transients

on the device output are suppressed by turning

the output driver OFF during the first

undervoltage, VCC(UV), (or negative) condition,

or first overvoltage (positive) condition,

VCC(OV), and maintaining a power up reset

mode until normal power is restored. Note

that after the initial transient, the output does

not change logic state during subsequent

power supply noise pulses.

An external 0.1 µF to 0.5 µF capacitor,

with good high-frequency characteristics,

should be connected between terminals 1 and 2

to bypass high-voltage noise and reduce EMI

susceptibility.

OUT

FIRST B

AFTER

TRANSIENT(S)

Dwg. WH-007-2A

OUT

CLASSICAL OUTPUT RESPONSE

A3197– OUTPUT RESPONSE

Power Up Reset. These devices are de-

signed to power up with the output OFF

without regard to any magnetic field applied.

The output will remain OFF until the flux is

reduced to below BRP (S-N transition) and then

BOP is exceeded, depending on the turn-on

state of the internal latches.

OUT

FIRST B

AFTER

POWER UP

Dwg. WH-006

OUT(SAT)

-B

OUT

FIRST B

AFTER

TRANSIENT(S)

Dwg. WH-007-1A

OUT

CLASSICAL OUTPUT RESPONSE

A3197– OUTPUT RESPONSE

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

www.allegromicro.com

ISO

Pulse No. Test Test Conditions (over operating temperature range)

1 Inductive Turn Off (Negative) VS = -100 V, RS = 10 Ω, tr = 1 µs, td = 2 ms

2 Inductive Turn Off (Positive) VS = 100 V, RS = 10 Ω, tr = 1 µs, td = 50 µs

3a Capacitive/Inductive Coupling (Neg) VS = -150 V, RS = 50 Ω, tr = 50 ns, td = 100 ns

3b Capacitive/Inductive Coupling (Pos) VS = 100 V, RS = 50 Ω, tr = 50 ns, td = 100 ns

4 Reverse Battery VS = -14 V, td = 20 s

5 Load Dump (ISO) VS = 86.5 V, RS = 0.5 Ω, tr = 5 ms, td = 400 ms

(DIN) VS = 120 V, RS = 0.5 Ω, tr = 100 ns, td = 400 ms

6 Ignition Coil Disconnect VS = -300 V, RS = 30 Ω, tr = 60 µs, td = 300 µs

EXTERNAL PROTECTION REQ’D

7 Field Decay (Negative) VS = -80 V, RS = 10 Ω, tr = 5 ms, td = 100 ms

INTERNAL PROTECTIVE FEATURES

Power supply voltage transients, or device output short circuits,

may be caused by faulty connectors, crimped wiring harnesses, or

service errors. To prevent catastrophic failure, internal protection

against overvoltage, reverse voltage, output overloads, and thermal

stress have been incorporated to meet the automotive 12 volt system

protection requirements of ISO DP7637/1 and DIN 40839-1. A series-

blocking diode or current-limiting resistor is required in order to

survive pulse number six.

12 V

trtd

0.9 V

0.1 V

Dwg. WH-008

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

115 Northeast Cutoff, Box 15036

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

Test Method and No. of Samples

Qualification Test Test Conditions Lots Test Length Per Lot Comments

Biased Humidity JESD22-A101 3 1200 hrs 116 Device biased for

TA = 85°C, RH = 85% minimum power

High-Temperature JESD22-A108 3 1200 hrs 116

Operating Life TA = 150°C, TJ = 165°C

Surge Operating Life JESD22-A108 1 504 hrs 116

TA = 175°C, TJ = 190°C

Pressure Cooker, JESD22-A102, Method C 3 96 hrs 77

Unbiased

Storage Life MIL-STD-883, Method 1008 1 1200 hrs 77

TA = 170°C

Temperature Cycle MIL-STD-883, Method 1010 3 1000 cycles 153

ESD MIL-STD-883, Method 3015 1 Pre/Post 3 per Test to failure

Human Body Model Reading test HBM > 16 kV

ESD 1 Pre/Post 3 per Test to failure

Machine Model Reading test MM > 800 V

Output Overloads. Current through the output transis-

tor is sensed with a low-value on-chip aluminum resistor.

The voltage drop across this resistor is fed back to control

the base drive of the output stage. This feedback prevents

the output transistor from exceeding its maximum current

density rating by limiting the output current to between

35 mA and 70 mA. Under short-circuit conditions, the

device will dissipate an increased amount of power (PD =

VOUT x ILIMIT) and the output transistor will be thermally

stressed.

Thermal Stress. When thermal stresses (either internal

or external) cause the junction temperature to exceed

+165°C, thermal shutdown of the output transistor is

activated. The thermal shutdown circuitry only provides

protection against thermal stresses caused by increased

power dissipation of the output transistor.

Overvoltage. The device protects itself against high-

voltage transients by shutting OFF all supply-referenced

active components, reducing the supply current, and

minimizing device power dissipation. Overvoltage

shutdown can occur anywhere between 28 V and 55 V and

device operation above 28 V cannot be recommended.

Under a sustained overvoltage, the device may be required

to dissipate an increased amount of power (PD = VCC x

ICC) and the device may be thermally stressed (see above).

Output Voltage. The output is clamped with an on-chip

Zener diode to limit the maximum output voltage that can

occur during overvoltage faults or when switching an

inductive load.

When any fault condition is removed, the device returns to

normal operating mode.

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.

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

www.allegromicro.com

APPLICATIONS INFORMATION

The A3197LLT and A3197LU latches have been optimized for

use in automotive ring magnet sensing applications. Such applications

include transmission speed sensors, motor position encoders, and wheel

bearing speed sensors. Special care has been taken to optimize the

operation of these devices in automotive subsystems that require ISO

DP9637 protection but NOT operation. Undervoltage lockout is in-

cluded to prevent propagation of false logic pulses during low battery,

cold-start conditions. Noise suppression is included to prevent false

switching of the device when subjected to ISO transients. Short-circuit

protection is included to prevent damage caused by pinched wiring

harnesses.

A typical application consists of a ferrite ring magnet located on a

rotating shaft. Typically, this shaft is attached to the transmission, the

sensor is mounted on a board, with care being taken to keep a tight

tolerance on the air gap between the package face and the magnet. The

device will provide a change in digital state at the transition of every

magnetic pole and, thus, give an indication of the transmission speed.

The high magnetic hysteresis allows the device to be immune to vibra-

tion of the magnet shaft and relatively good duty cycles can be obtained.

Hall effect applications information is available in the “Hall-Effect

IC Applications Guide”, which can be found in the Allegro

MicroSystems Electronic Data Book, AMS-702, or Application Note

2770, or at

www.allegromicro.com.

SENSOR LOCATIONS

(±0.005" [0.13 mm] die placement)

SUFFIX “LT”

SUFFIX “U”

1 32

Dwg. MH-008-5B

0.0305"

0.775 mm

NOM

ACTIVE AREA DEPTH

0.051"

1.30 mm

0.092"

2.35 mm

1 3

Dwg. MH-002-12B

0.0165"

0.42 mm

NOM

0.073"

1.85 mm

BRANDED

SURFACE

ACTIVE AREA DEPTH

0.094"

2.40 mm

Allegro

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

115 Northeast Cutoff, Box 15036

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

A3197ELT and A3197LLT

Dimensions in Inches

(for reference only)

Dimensions in Millimeters

(controlling dimensions)

NOTE — Exact body and lead configuration at vendor’s option within limits shown.

Dwg. MA-009-3A mm

123

4.60

4.40

1.83

1.62

4.25

3.94

1.50

BSC

0.48

0.36

1.20

0.89

2.60

2.29

1.60

1.40 0.44

0.35

2.29

2.13

0.56

0.44

3.00

BSC

Dwg. MA-009-3A in

123

0.072

0.064

0.167

0.155

0.059

BSC

0.0189

0.0142

0.047

0.035

0.102

0.090

0.063

0.055 0.0173

0.0138

0.090

0.084

0.0221

0.0173

0.118

BSC

0.181

0.173

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

www.allegromicro.com

A3197EU and A3197LU

Dimensions in Inches Dimensions in Millimeters

(controlling dimensions) (for reference only)

NOTES:1. Tolerances on package height and width represent allowable mold offsets.

Dimensions given are measured at the widest point (parting line).

2. Exact body and lead configuration at vendor’s option within limits shown.

3. Height does not include mold gate flash.

4. Recommended minimum PWB hole diameter to clear transition area is 0.035" (0.89 mm).

5. Where no tolerance is specified, dimension is nominal.

Dwg. MH-003E in

0.063

0.059

0.018

0.0173

0.0138

0.0189

0.0142

0.050

1 2 3

0.100

45°

SEE NOTE

0.183

0.178

0.181

0.176

0.600

0.560

0.086

MAX

Dwg. MH-003E mm

1.60

1.50

0.46

0.44

0.35

0.48

0.36

1.27

1 2 3

2.54

45°

SEE NOTE

4.65

4.52

4.60

4.47

15.24

14.23

2.18

MAX

3197

PROTECTED, HIGH-TEMP.,

OPEN-COLLECTOR

HALL-EFFECT LATCH

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; 5,729,130; 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 responsibil-

ity for its use; nor for any infringements of patents or other rights of

third parties that may result from its use.