A1147 [ALLEGRO]

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches; 低电流超灵敏双线式稳定斩波型单极霍尔效应开关


型号：	A1147
厂家：	ALLEGRO MICROSYSTEMS
描述：	Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches 低电流超灵敏双线式稳定斩波型单极霍尔效应开关开关
文件：	总13页 (文件大小：319K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized

Unipolar Hall Effect Switches

The A1147 and A1148 devices are two-wire, unipolar, Hall effect switches that are

factory-programmed at end-of-line to optimize ultrasensitive magnetic switchpoint

accuracy. These devices use a patented high frequency chopper-stabilization tech-

nique, produced using the Allegro advanced BiCMOS wafer fabrication process,

to achieve magnetic stability and to eliminate offset inherent in single-element

devices exposed to harsh application environments.

Package LH, 3-pin SOT

≈1:1

Commonly found in a number of automotive applications, these switches are

utilized to sense seat track position, seat belt buckle presence, hood/trunk latch-

ing, and shift selector position. Two-wire unipolar switches, such as the A1147

and A1148, are particularly advantageous in price-sensitive applications because

they require one less wire for operation than do switches with the more traditional

open-collector output. Additionally, the system designer inherently gains diagnos-

tics because there is always output current flowing, which should be in either of

two narrow ranges. Any current level not within these ranges indicates a fault con-

dition. These devices also feature on-chip transient protection and a Zener clamp

to protect against overvoltage conditions on the supply line.

Package UA, 3-pin SIP

The output currents of the A1148 switches HIGH in the presence of a south (+)

polarity magnetic field of sufficient strength, and switches LOW otherwise, as in

the presence of a weak field or a north (–) polarity field. The A1147 has an oppo-

site output: the currents switch LOW in the presence of a south-polarity magnetic

field of sufficient strength, and switch HIGH otherwise.

≈1:1

Both versions are offered in two package styles. The LH is a SOT-23W, miniature

low-profile package for surface-mount applications. The UA is a three-lead ultra-

mini SIP for through-hole mounting. Each package is available in a lead (Pb) free

version (suffix, –T) with 100% matte tin plated leadframe. Field-programmable

versions also available: A1180 and A1181.

ABSOLUTE MAXIMUM RATINGS

Features and Benefits

ꢀChopper stabilization

ꢀOn-chip protection

Supply Voltage, V_CC..........................................28 V

Reverse-Supply Voltage, V_RCC........................–18 V

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

Power Dissipation, P_D............................ Graph, p. 5

Operating Temperature

Ambient, T_A, Range E..................–40ºC to 85ºC

Ambient, T_A, Range L................–40ºC to 150ºC

Maximum Junction, T_J(max)........................165ºC

Storage Temperature, T_S..................–65ºC to 170ºC

ꢀLow switchpoint drift over operating

ꢀSupply transient protection

ꢀReverse-battery protection

ꢀOn-board voltage regulator

ꢀ3.5 to 24 V operation

temperature range

ꢀLow sensitivity to stress

ꢀFactory programmed at end-of-line for

optimized switchpoints

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

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

www.allegromicro.com

A1147-DS, Rev. 6

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

Functional Block Diagram

V+

VCC

Regulator

To All Subcircuits

Clock/Logic

0.01 uF

Low-Pass

Filter

Amp

GND

Package UA Only

Package LH, 3-pin SOT

Package UA, 3-pin SIP

1. VCC

2. GND

3. GND

2. No connection

3. GND

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

ELECTRICAL CHARACTERISTICS over the operating voltage and temperature ranges, unless otherwise specified

Characteristic

Supply Voltage¹

Symbol

V_CC

Test Conditions

Min.

3.5

Typ.

Max.

Units

–

I_CCL

B > B_OPfor A1147; B < B_RPfor A1148

B > B_OPfor A1148; B < B_RPfor A1147

V_RCC= –18 V

Supply Current²

I_CCH

Reverse Supply Current

I_RCC

–

–1.6

Supply Zener Clamp Voltage

Supply Zener Clamp Current³

V_ZSUPPLYI_CC= I_CCL(max)+ 3 mA; T_A= 25°C

I_ZSUPPLYV_ZSUPPLY= 28 V

Capacitance of the oscilloscope performing

the measurement = 20 pF

Output Slew Rate⁴

di/dt

–

mA/μs

Chopping Frequency

Power-On Time⁵

f_C

–

200

–

kHz

μs

–

C_BYPASS= 0.01 μF

t_on

Power-On State^6,7

POS

t < t_on; V_CCslew rate > 25 mV/μs

HIGH

¹V_CCrepresents the generated voltage between the VCC pin and the GND pin.

²Relative values of B use the algebraic convention, where positive values indicate south magnetic polarity, and negative values indicate north magnetic

polarity; therefore greater B values indicate a stronger south polarity field (or a weaker north polarity field, if present).

³I_ZSUPPLY(max)= I_CCL(max)+ 3 mA.

⁴Measured without bypass capacitor between VCC and GND. Use of a bypass capacitor results in slower current change.

⁵Measured with and without bypass capacitor of 0.01 μF. Adding a larger bypass capacitor causes longer Power-On Time.

⁶POS is defined as true only with a V_CCslew rate of 25 mV/μs or greater. Operation with a V_CCslew rate less than 25 mV/μs can permanently harm

device performance.

⁷POS is undefined for t > t_onor B_RP< B < B_OP

MAGNETIC CHARACTERISTICS over the operating voltage and temperature ranges, unless otherwise specified

Characteristic

Symbol

Test Conditions

A1147 I_CC= I_CCL

A1148 _CC= I_CCH

A1147 I_CC= I_CCH

A1148 _CC= I_CCL

B_HYS= B_OP– B_RP

Min.

Typ.*

Max.

Units

Operate Point

B_OP

Release Point

Hysteresis

B_RP

B_HYS

*Typical data are for initial design estimations only, and assume optimum manufacturing and application conditions, such as T_A= 25°C and V_CC= 12 V.

Performance may vary for individual units, within the specified maximum and minimum limits.

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

Characteristic Data

Supply Current (Low) versus Ambient Temperature

at Various Levels of V_CC

(A1147 and A1148)

Supply Current (High) versus Ambient Temperature

at Various Levels of V_CC

(A1147 and A1148)

V_CC

3.5 V

V_CC

3.5 V

12.0 V

24.0 V

12.0 V

24.0 V

–50

100

150

200

–50

100

150

200

Ambient Temperature, T_A(°C)

Operate Point versus Ambient Temperature

at Various Levels of V_CC

(A1147 and A1148)

Switchpoint Hysteresis versus Ambient Temperature

at Various Levels of V_CC

(A1147 and A1148)

V_CC

3.5 V

12.0 V

24.0 V

3.5 V

12.0 V

24.0 V

–50

100

150

200

–50

100

150

200

Ambient Temperature, T_A(°C)

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information

Characteristic

Symbol

Test Conditions*

Value Units

Package LH, 1-layer PCB with copper limited to solder pads

228 ºC/W

Package LH, 2-layer PCB with 0.463 in.²of copper area each side

connected by thermal vias

R_θJA

Package Thermal Resistance

110

ºC/W

Package UA, 1-layer PCB with copper limited to solder pads

165 ºC/W

*Additional thermal information available on Allegro Web site.

Power Derating Curve

CC(max)

2-layer PCB, Package LH

(R_θJA= 110 ºC/W)

1-layer PCB, Package UA

(R_θJA= 165 ºC/W)

1-layer PCB, Package LH

(R_θJA= 228 ºC/W)

CC(min)

100

120

140

160

180

Temperature (ºC)

Power Dissipation versus Ambient Temperature

1900

1800

1700

1600

1500

1400

1300

1200

1100

1000

900

800

700

600

500

400

300

200

100

120

140

160

180

Temperature (°C)

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

Functional Description

Operation

The output, I_CC, of the A1147 device switches low after the mag-

netic field at the Hall sensor exceeds the operate point threshold,

B_OP. When the magnetic field is reduced to below the release

point threshold, B_RP, the device output goes high. The differ-

ences between the magnetic operate and release point is called

the hysteresis of the device, B_HYS. This built-in hysteresis allows

clean switching of the output even in the presence of external

mechanical vibration and electrical noise. The A1148 device

switches with opposite polarity for similar B_OPand B_RPvalues,

in comparison to the A1147 (see figure 1).

I+

I_CC(H)

I_CC(L)

B+

B–

B+

B–

B_HYS

(A) A1147

(B) A1148

Figure 1. Alternative switching behaviors are available in the A114x device family. On the horizontal axis, the B+ direction indicates

increasing south polarity magnetic field strength, and the B– direction indicates decreasing south polarity field strength (including the

case of increasing north polarity).

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

Chopper Stabilization Technique

The chopper stabilization technique uses a 200 kHz high

frequency clock. For demodulation process, a sample and hold

technique is used, where the sampling is performed at twice the

chopper frequency (400 kHz). This high-frequency operation

allows a greater sampling rate, which results in higher accuracy

and faster signal-processing capability. This approach desensi-

tizes the chip to the effects of thermal and mechanical stresses,

and produces devices that have extremely stable quiescent Hall

output voltages and precise recoverability after temperature

cycling. This technique is made possible through the use of a

BiCMOS process, which allows the use of low-offset, low-noise

amplifiers in combination with high-density logic integration

and sample-and-hold circuits.

When using Hall-effect technology, a limiting factor for

switchpoint accuracy is the small signal voltage developed

across the Hall element. This voltage is disproportionally small

relative to the offset that can be produced at the output of the

Hall sensor. This makes it difficult to process the signal while

maintaining an accurate, reliable output over the specified oper-

ating temperature and voltage ranges.

Chopper stabilization is a unique approach used to minimize

Hall offset on the chip. The patented Allegro technique, namely

Dynamic Quadrature Offset Cancellation, removes key sources

of the output drift induced by thermal and mechanical stresses.

This offset reduction technique is based on a signal modulation-

demodulation process. The undesired offset signal is separated

from the magnetic field-induced signal in the frequency domain,

through modulation. The subsequent demodulation acts as a

modulation process for the offset, causing the magnetic field-

induced signal to recover its original spectrum at baseband, while

the dc offset becomes a high-frequency signal. The magnetic-

sourced signal then can pass through a low-pass filter, while the

modulated dc offset is suppressed. This configuration is illus-

trated in figure 2.

The repeatability of magnetic field-induced switching is affected

slightly by a chopper technique. However, the Allegro high-

frequency chopping approach minimizes the affect of jitter and

makes it imperceptible in most applications. Applications that

are more likely to be sensitive to such degradation are those

requiring precise sensing of alternating magnetic fields; for

example, speed sensing of ring-magnet targets. For such applica-

tions, Allegro recommends its digital sensor families with lower

sensitivity to jitter. For more information on those devices,

contact your Allegro sales representative.

Regulator

Clock/Logic

Low-Pass

Filter

Hall Element

Amp

Figure 2. Chopper stabilization circuit (Dynamic Quadrature Offset Cancellation)

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

Application Information

Typical Application Circuit

The A114x family of devices must be protected by an external

V+

bypass capacitor, C_BYP, connected between the supply, VCC,

and the ground, GND, of the device. C_BYPreduces both external

VCC

noise and the noise generated by the chopper-stabilization func-

tion. As shown in figure 3, a 0.01 μF capacitor is typical.

A114x

BYP

Installation of C_BYPmust ensure that the traces that connect it to

the A114x pins are no greater than 5 mm in length.

0.01 μF

GND

All high-frequency interferences conducted along the supply

lines are passed directly to the load through C_BYP, and it serves

only to protect the A114x internal circuitry. As a result, the load

ECU (electronic control unit) must have sufficient protection,

other than C_BYP, installed in parallel with the A114x.

Package UA Only

Maximum separation 5 mm

R_SENSE

A series resistor on the supply side, RS (not shown), in combina-

tion with C_BYP, creates a filter for EMI pulses.

When determining the minimum V_CCrequirement of the A114x

device, the voltage drops across R_Sand the ECU sense resistor,

R_SENSE, must be taken into consideration. The typical value for

R_SENSEis approximately 100 Ω.

ECU

Figure 3. Typical application circuit

For additional general application information, visit the Allegro

Web site at www. allegromicro.com.

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

Power Derating

Example: Reliability for V_CCat T_A=150°C, package UA, using

minimum-K PCB.

The device must be operated below the maximum junction

temperature of the device, T_J(max). Under certain combinations of

peak conditions, reliable operation may require derating sup-

plied power or improving the heat dissipation properties of the

application. This section presents a procedure for correlating

factors affecting operating T_J. (Thermal data is also available on

the Allegro MicroSystems Web site.)

Observe the worst-case ratings for the device, specifically:

R_θJA=165°C/W, T_J(max)=165°C, V_CC(max)= 24 V, and

I_CC(max)= 17 mA.

Calculate the maximum allowable power level, P_D(max). First,

invert equation 3:

The Package Thermal Resistance, R_θJA, is a figure of merit sum-

marizing the ability of the application and the device to dissipate

heat from the junction (die), through all paths to the ambient air.

Its primary component is the Effective Thermal Conductivity,

K, of the printed circuit board, including adjacent devices and

traces. Radiation from the die through the device case, R_θJC, is

relatively small component of R_θJA. Ambient air temperature,

T_A, and air motion are significant external factors, damped by

overmolding.

ΔT_max= T_J(max)– T_A= 165°C–150°C = 15°C

This provides the allowable increase to T_Jresulting from internal

power dissipation. Then, invert equation 2:

P_D(max)= ΔT_max÷R_θJA=15°C÷165 °C/W=91mW

Finally, invert equation 1 with respect to voltage:

V_CC(est)= P_D(max)÷ I_CC(max)= 91mW÷17mA=5 V

The result indicates that, at T_A, the application and device can

The effect of varying power levels (Power Dissipation, P_D), can

be estimated. The following formulas represent the fundamental

relationships used to estimate T_J, at P_D.

dissipate adequate amounts of heat at voltages ≤V_CC(est)

Compare V_CC(est)to V_CC(max). If V_CC(est)≤ V_CC(max), then reli-

able operation between V_CC(est)and V_CC(max)requires enhanced

R_θJA. If V_CC(est)≥ V_CC(max), then operation between V_CC(est)and

V_CC(max)is reliable under these conditions.

P_D= V_IN

(1)

(2)

(3)

ΔT = P_D

θJA

T_J= T_A+ ΔT

For example, given common conditions such as: T_A= 25°C,

V_CC= 12 V, I_CC= 4 mA, and R_θJA= 140 °C/W, then:

P_D= V_CC

= 12 V 4 mA = 48 mW

ΔT = P_D

= 48 mW 140 °C/W = 7°C

θJA

T_J= T_A+ ΔT = 25°C + 7°C = 32°C

A worst-case estimate, P_D(max), represents the maximum allow-

able power level (V_CC(max), I_CC(max)), without exceeding T_J(max)

at a selected R_θJAand T_A.

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

Device Qualification Program

Contact Allegro for information.

EMC (Electromagnetic Compatibility) Requirements

Contact your local representative for EMC results.

Test Name

ESD – Human Body Model

ESD – Machine Model

Conducted Transients

Direct RF Injection

Bulk Current Injection

TEM Cell

Reference Specification

AEC-Q100-002

AEC-Q100-003

ISO 7637-1

ISO 11452-7

ISO 11452-4

ISO 11452-3

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

Product Selection Guide

Use the complete part numbers when ordering

Operating Ambient

Output Level in

Part Number

A1147ELHLT

Pb-Free

Packing^a

Package

Temperature, T_A

(°C)

South (+) Field^b

–

Yes

–

Tape and Reel, 3000 pieces/reel

Bulk Bag, 500 pieces/bag

Surface Mount

A1147ELHLT-T

A1147EUA

–40 to 85

–40 to 150

–40 to 85

–40 to 150

A1147EUA-T

A1147EUATI

A1147EUATI-T

A1147LLHLT

A1147LLHLT-T

A1147LUA

Yes

–

Through Hole

Surface Mount

Through Hole

Surface Mount

Through Hole

Surface Mount

Through Hole

Tape and Reel, 2000 pieces/reel

Tape and Reel, 3000 pieces/reel

Bulk Bag, 500 pieces/bag

Yes

–

Low

Yes

–

A1147LUA-T

A1147LUATI

A1147LUATI-T

A1148ELHLT

A1148ELHLT-T

A1148EUA

Yes

–

Tape and Reel, 2000 pieces/reel

Tape and Reel, 3000 pieces/reel

Bulk Bag, 500 pieces/bag

Yes

–

Yes

–

A1148EUA-T

A1148EUATI

A1148EUATI-T

A1148LLHLT

A1148LLHLT-T

A1148LUA

Yes

–

Tape and Reel, 2000 pieces/reel

Tape and Reel, 3000 pieces/reel

Bulk Bag, 500 pieces/bag

Yes

–

High

Yes

–

A1148LUA-T

A1148LUATI

A1148LUATI-T

Yes

–

Tape and Reel, 2000 pieces/reel

Yes

^aContact Allegro for additional packing options.

^bSouth (+) magnetic fields must be of sufficient strength.

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

Package LH, 3-Pin; (SOT-23W)

3.10 .122

2.90 .114

1.49 .059

NOM

8º

0º

0.70 .028

BSC

0.28 .011

NOM

0.20 .008

0.13 .005

0.96 .038

NOM

2.40 .094

BSC

2.10 .083

1.85 .073

3.00 .118

2.70 .106

0.25 .010

MIN

1.00 .039

BSC

0.95 .037

BSC

0.25 .010

BSC

Seating Plane

Gauge Plane

Dimensions in millimeters

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

Hall element

0.50 .020

0.30

1.13 .045

0.87 .034

Active Area Depth 0.28 [.011]

Fits SC–59A Solder Pad Layout

.012

0.55 .022

REF

0.15 .006

0.00 .000

0.95 .037

BSC

Package UA, 3-Pin SIP

.164 4.17

.159 4.04

45°

BSC

.0195 0.50

NOM

.0805 2.04

.062 1.57

NOM

.058 1.47

1.44

.0565

NOM

.122 3.10

.117 2.97

45°

BSC

.085 2.16

MAX

.031 0.79

REF

.640 16.26

.600 15.24

.017 0.44

.014 0.35

.019 0.48

.014 0.36

.050 1.27

BSC

Dimensions in inches

Metric dimensions (mm) in brackets, for reference only

Dambar removal protrusion

Hall element

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 and A1148

Low Current Ultrasensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches

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 pend-

ing.

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 manufactur-

ability 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 devices or systems without express written approval.

The information included herein is believed to be accurate and reli-

able. 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.

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

A1147-DS, Rev. 6

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

www.allegromicro.com

A1147 [ALLEGRO]

相关型号：

A1147ELHLT

A1147ELHLT-T

A1147EUA

A1147EUA-T

A1147EUATI

A1147EUATI-T

A1147LLHLT

A1147LLHLT-T

A1147LUA

A1147LUA-T

A1147LUATI

A1147LUATI-T