Datasheet A3421EKA, A3422LKA-TL, A3422LKA, A3422EKA-TL, A3422EKA Datasheet (Allegro)

The A3421xKA and A3422xKA Hall-effect, direction-detection
sensors are a new generation of special-function integrated sensors that
are capable of sensing the direction of rotation of a ring magnet. These
transducers provide separate digital outputs that provide information on
magnet rotation speed, direction, and magnet pole count. These devices
eliminate the major manufacturing hurdles encountered in fine-pitch
direction-detection applications, namely maintaining accurate mechani­cal location between the two active Hall elements. Here, the two Hall
elements are photolithographically aligned to better than 1 µm, as
contrasted with 100 µm or worse mechanical location tolerance when
manufactured discretely. These highly sensitive, temperature-stable,
magnetic transducers are ideal for use in digital-encoder systems in the
harsh environments of automotive or industrial applications. The
A3421xKA is a high-hysteresis device designed for low-resolution
pulse counting while the A3422xKA is a high-sensitivity device
optimized for use with high-density magnets.

The A3421xKA and A3422xKA monolithic integrated circuits
contain two independent Hall-effect latches whose digital outputs are
internally coupled to CMOS logic circuitry that decodes signal speed
and direction. Extremely low-drift BiCMOS circuitry is used for the
amplifiers to ensure symmetry between the two latches so that signal
quadrature can be maintained. An on-chip voltage regulator allows the
use of these devices from a 4.5 V to 18 V supply. Both devices have
standard open-collector outputs; the logic operation of both devices is
the same.

Two operating temperature ranges are provided; suffix ‘E–’ is for
the automotive and industrial temperature range of -40°C to +85°C,
suffix ‘L–’ is for the automotive and military temperature range of

-40°C to +150°C. The 5-pin ‘KA’ SIP package provides a cost-com­petitive solution to linear magnetic sensing in harsh environments.

FEATURES

■ Internal Direction-Decoding Circuitry

■ Two Matched Hall Latches On A Single Substrate

■ Superior Temperature Stability

■ 4.5 V to 18 V Operation

Electrically Defined Power-On State
Under-Voltage Lockout

HALL-EFFECT,

DIRECTION-DETECTION SENSORS

Always order by complete part number, e.g., A3421EKA .

X

V

CC

1 432 5

Dwg. PH-015

SUPPLY

DIRECTION

GROUND

E1 OUTPUT

SPEED

LOGIC

X

E1 E2

Pinning is shown viewed from branded side.

ABSOLUTE MAXIMUM RATINGS

Supply Voltage, VCC. . . . . . . . . . . . . 18 V

Magnetic Flux Density, B . . . . Unlimited

Output OFF Voltage, V

OUT

. . . . . . . . V

CC

Output Sink Current, I

OUT

. . . . . . . 30 mA

Package Power Dissipation,

PD. . . . . . . . . . . . . . . . . . . . . . 500 mW

Operating Temperature Range, T

A

Suffix ‘EKA’ . . . . . . . -40˚C to +85˚C

Suffix ‘LKA’ . . . . . . -40˚C to +150˚C

Storage Temperature Range,

TS. . . . . . . . . . . . . . . -65˚C to +170˚C

3421

AND

3422

PRELIMINARY INFORMATION

(subject to change without notice)

September 6, 2000

Data Sheet

27650.1

3421

AND

3422

HALL-EFFECT,
DIRECTION-DETECTION
SENSORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]

FUNCTIONAL BLOCK DIAGRAM

TIMING DIAGRAM

B

OP1

B

RP1

Dwg. WH-012A

0

+B

-B

0

+B

-B

B

RP2

OUT

E1

OUT

E2

(INTERNAL)

SPEED

(OUT

E1

XOR OUTE2)

B

OP2

DIRECTION

CHANGE IN DIRECTION

t

d

SPEED

4

DIRECTION2

E1 OUTPUT

1

X X

Dwg. FH-018

GROUND

5

3

LOGIC

E1

E2

SUPPLY

POWER-ON

LOGIC

REG

UVLO

Copyright © 1999 Allegro MicroSystems, Inc.

3421

AND

3422

HALL-EFFECT,

DIRECTION-DETECTION

SENSORS

www.allegromicro.com

Limits

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Supply Voltage Range V

CC

Operating, TJ < 165°C

1

4.5 — 18 V

Output Leakage Current I

OFF

V

OUT

= VCC = 18 V — <1.0 10 µA

Output Saturation Voltage V

OUT(SAT)IOUT

= 20 mA — 0.21 0.50 V

Power-On State POS VCC = 0 → 5 V, OFF OFF OFF —

B

RP1

< B < B

OP1

, B

RP2

< B < B

OP2

Under-Voltage Lockout V

CC(UV)IOUT

= 20 mA, VCC = 0 → 5 V — 3.5 — V

Under-Voltage Hysteresis V

CC(hys)

Lockout (V

CC(UV)

) - Shutdown — 0.5 — V

Power-On Time t

po

VCC > 4.5 V — — 50 µs

Output Rise Time t

r

CL = 20 pF, RL = 820 Ω — 200 — ns

Output Fall Time t

f

CL = 20 pF, RL = 820 Ω — 200 — ns

Direction Change Delay t

d

CL = 20 pF, RL = 820 Ω 0.5 1.0 5.0 µs

Supply Current I

CC

VCC = 8 V, All outputs OFF 5.0 9.0 18 mA

ELECTRICAL CHARACTERISTICS over operating temperature range.

50 75 100 125 175

0.5

0.1

0

ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS

TEMPERATURE IN °C

0.4

0.3

0.2

25

Dwg. GH-069

R

θJA

= 164°C/W

0.6

150

NOTES:1. Maximum supply voltage must be adjusted for power dissipation and ambient temperature.

2. Typical Data is at VCC = 12 V and TA = +25°C and is for design information only.

3421

AND

3422

HALL-EFFECT,
DIRECTION-DETECTION
SENSORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]

A3421xKA A3422xKA

Characteristic Symbol Test Conditions Min. Typ. Max. Min. Typ. Max. Units

Operate Point B

OP

TA = -40°C 140 185 300 — 29 85 G

TA = +25°C 130 160 280 — 29 75 G

TA = Maximum 120 — 260 — — 75 G

Release Point

3

B

RP

TA = -40°C -300 -190 -140 -85 -19 — G

TA = +25°C -280 -175 -130 -75 -18 — G

TA = Maximum -260 — -120 -75 -16 — G

Hysteresis B

hys

TA = -40°C 280 375 — 10 48 — G

TA = +25°C 260 335 — 10 46 — G

TA = Maximum 240 — — 10 — — G

Operate Differential B

OP1

- B

OP2

——±80 — — ±60 G

Release Differential B

RP1

- B

RP2

——±80 — — ±60 G

MAGNETIC CHARACTERISTICS over operating voltage range.

NOTES:1. Magnetic flux density is measured at most sensitive area of device,

nominally located 0.014” (0.37 mm) below the branded face of the package.

2. Typical Data is at VCC = 12 V and TA = +25°C and is for design information only.

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

3421

AND

3422

HALL-EFFECT,

DIRECTION-DETECTION

SENSORS

www.allegromicro.com

TYPICAL A3421xKA CHARACTERISTICS

TYPICAL A3422xKA CHARACTERISTICS

0 50 100

AMBIENT TEMPERATURE IN °C

-50

Dwg. GH-026-1

SWITCH POINTS IN GAUSS

0

10

OPERATE POINT

RELEASE POINT

150-25 25 75 125

20

30

40

50

-50

-40

-30

-20

-10

V = 8 V

CC

0 25 50 75

100

AMBIENT TEMPERATURE IN °C

-50

Dwg. GH-051-1

125-25

HYSTERESIS IN GAUSS

20

0

150

80

100

60

40

V = 8 V

CC

0 50 100

AMBIENT TEMPERATURE IN °C

-50

Dwg. GH-026-2

SWITCH POINTS IN GAUSS

0

50

OPERATE POINT

RELEASE POINT

150-25 25 75 125

100

150

200

250

-250

-200

-150

-100

-50

V = 8 V

CC

0 25 50 75

100

AMBIENT TEMPERATURE IN °C

-50

Dwg. GH-051-2

125-25

HYSTERESIS IN GAUSS

100

0

150

400

500

300

200

V = 8 V

CC

3421

AND

3422

HALL-EFFECT,
DIRECTION-DETECTION
SENSORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]

TYPICAL ELECTRICAL CHARACTERISTICS

0 25 50 75

100

AMBIENT TEMPERATURE IN °C

-50

Dwg. GH-053-1

125-25

SUPPLY CURRENT IN mA

10

9.0

8.0

7.0

6.0
150

V = 8 V

CC

ALL OUTPUTS ON

ALL OUTPUTS OFF

0 25 50 75

100

300

0

AMBIENT TEMPERATURE IN °C

200

100

-50

Dwg. GH-029-2

SATURATION VOLTAGE IN mV

150

-25

125

I = 20 mA

OUT

250

150

50

12

SUPPLY VOLTAGE IN VOLTS

10

8.0

6.0

Dwg. GH-058-3

SUPPLY CURRENT IN mA

11

9.0

7.0

13

5.0

ALL OUTPUTS ON

ALL OUTPUTS OFF

2.0 6.0 10 14 18

T = 25°C

A

3421

AND

3422

HALL-EFFECT,

DIRECTION-DETECTION

SENSORS

www.allegromicro.com

Outputs. The device provides three saturated outputs:
DIRECTION, E1 OUTPUT, and SPEED. DIRECTION
provides the direction output of the sensor and is defined
as OFF (high) for the direction E1 to E2 and ON (low) for
the direction E2 to E1. SPEED provides an XOR’d output
of the two sensors. Because of internal delays, DIREC­TION will always be updated before SPEED and is
updated at every transition of E1 OUTPUT and E2 OUT­PUT (internal) allowing the use of up-down counters
without the loss of pulses.

Power-On State. At power on, the logic circutry is reset
to provide an OFF (high) at DIRECTION and an OFF
(high) for E1 and E2 (internal) for magnetic fields less
than B

OP

. This eliminates ambiguity when the device is

powered up and either sensor detects a field between B

OP

and BRP. If either sensor is subjected to a field greater than
B

OP

, the internal logic will set accordingly.

The integrated circuit contains an internal voltage regula­tor that powers the Hall sensors and both the analog and
digital circuitry. This regulator allows operation over a
wide supply voltage range and provides some immunity to
supply noise. The device also contains CMOS logic
circuitry that decodes the direction of rotation of the ring
magnet.

Quadrature/Direction Detection. Internal logic
circuitry provides outputs representing speed and direction
of the magnetic field across the face of the package. For
the direction signal to be appropriately updated, a quadra­ture relationship must be maintained between the ring
magnet pole width*, the sensor-to-sensor spacing, and, to a
lesser extent, the magnetic switch points. For optimal
design, the sensor should be actuated with a ring magnet
pole width* two times the sensor-to-sensor spacing. This
will produce a sinusoidal magnetic field whose period
(denoted as

Τ

) is then four times the sensor-to-sensor
spacing. A quadrature relationship can also be maintained
for a ring magnet that has a period that satisfies the rela­tionship n

Τ

/4 = 1.5 mm, where n is any odd integer.
Therefore, ring magnets with pole-pair spacings equal to 6
mm (n = 1), 2 mm (n = 3), 1.2 mm (n = 5), etc. are permit­ted.

The response of the device to the magnetic field
produced by a rotating ring magnet is shown on page 2.
Note the phase shift between the two integrated sensors.

* “Pole” refers to a single pole (North or South) unless
stated as “pole pair” (North

and South).

FUNCTIONAL DESCRIPTION

3421

AND

3422

HALL-EFFECT,
DIRECTION-DETECTION
SENSORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]

APPLICATIONS INFORMATION

Operation with Fine-Pitch Ring Magnets. 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 (see below). This sensor
rotation decreases the effective sensor-to-sensor spacing,
provided that the Hall elements are not rotated beyond the
width of the target.

Applications. It is strongly recommended that an
external 0.01 µF bypass capacitor be connected (in close
proximity to the Hall sensor) between the supply and
ground of the device to reduce both external noise and
noise generated by the internal logic.

The simplest form of magnet that will operate these
devices is a ring magnet. Other methods of operation,
such as linear magnets, are possible. Extensive applica­tions information on magnets and Hall-effect sensors is
also available in the “Hsall-Effect IC Applications Guide”
which can be found in the latest issue of the Allegro

MicroSystems Electronic Data Book, AMS-702 or Appli­cation Note 27701, or at

www.allegromicro.com

Dwg. MH-024

α

TARGET FACE WIDTH, F

>1.50 SIN

α

(mm)

>0.059 SIN

α

(inch)

1.50 COS

α

(mm)

0.059 COS

α

(inch)

A

0.059"

1.50 mm

12 4 53

A

1

2

4

5

3

Rotated sensor for
fine-pitch ring
magnets

3421

AND

3422

HALL-EFFECT,

DIRECTION-DETECTION

SENSORS

www.allegromicro.com

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 77 Device biased for
Bias Life TA = 85°C, RH = 85% minimum power

Bias Life JESD22-A108, 1000 hrs 77

TA = 150°C, TJ = 165°C

(Surge Operating Life) JESD22-A108, 1000 hrs 77

TA = 175°C, TJ = 190°C

Autoclave, Unbiased JESD22-A102, 96 hrs 77

TA = 121°C, 15 psig

High-Temperature JESD22-A103, 1000 hrs 77
(Bake) Storage Life TA = 170°C

Temperature Cycle JESD22-A104 1000 cycles 77 -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

SENSOR LOCATIONS

(±0.005” [0.13 mm] die placement)

A

E1 E2

Dwg. MH-007-1

0.014"

0.37 mm
NOM

BRANDED
SURFACE

ACTIVE AREA DEPTH

0.059"

1.50 mm

12 4 53

0.096"

2.44 mm

0.072"

1.83 mm

3421

AND

3422

HALL-EFFECT,
DIRECTION-DETECTION
SENSORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]

PACKAGE DESIGNATOR 'KA'

Dimensions in Inches

(controlling dimensions)

Dimensions in Millimeters

(for reference only)

Dwg. MH-010H in

0.018

0.0173

0.0138

0.0189

0.0142

0.050

BSC

13452

0.063

0.059

45°

0.600

0.560

0.083

MAX

0.252

0.247

0.181

0.176

SEE NOTE

SURFACE-MOUNT LEAD FORM (add ‘-TL’ to part number)

2.41

±0.13

0.51

MIN

FLAT

Dwg. MH-015 mm

0.10

MAX

0.051

MAX

0°–8°

0.095

±0.005

0.020

MIN

FLAT

Dwg. MH-015 in

0.004

MAX

0.002

MAX

0°–8°

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-010H mm

0.46

0.44

0.35

0.48

0.36

1.27

BSC

13452

1.60

1.50

45°

15.24

14.23

2.11

MAX

6.40

6.27

4.60

4.47

SEE NOTE

3421

AND

3422

HALL-EFFECT,

DIRECTION-DETECTION

SENSORS

www.allegromicro.com

HALL-EFFECT SENSORS

Partial Part Avail. Oper. Characteristics at TA = +25°C
Number Temp. BOP max BRP min B

hys

typ Features Notes

RATIOMETRIC, LINEAR HALL-EFFECT SENSORS

3503 S typ. 1.3 mV/G
3507 E/L typ. 2.5 mV/G
3508 S typ. 2.5 mV/G
3515 E/L typ. 5.0 mV/G chopper stabilized
3516 E/L typ. 2.5 mV/G chopper stabilized
3517 L/S typ. 5.0 mV/G chopper stabilized
3518 L/S typ. 2.5 mV/G chopper stabilized

GEARTOOTH/RING MAGNET (DUAL ELEMENT) HALL-EFFECT SENSORS in order of B

OP

3060 K/S +35 -35 30 ac coupled
3422 E/L +75 -75 46 direction detection
3059 K/S [phone] ac coupled
3056 E/L [phone] zero-speed
3058 E/L [phone] zero-speed
3421 E/L [phone] direction detection

SPECIAL-PURPOSE HALL-EFFECT SENSORS

3054 K/S +300 +5.0 50 unipolar switch, multiplexed 4
3209 E ±60 ±5.0 7.7 400 µW, chopper stabilized
3210 E ±60 ±5.0 7.7 25 µW, chopper stabilized
3421 E/L [phone] direction detection
3422 E/L +85 -85 46 direction detection
3425 L +24 -24 19 dual, chopper stabilized 1

Operating Temperature Ranges:

S = -20°C to +85°C, E = -40°C to +85°C, J = -40°C to +115°C, K = -40°C to +125°C, L = -40°C to +150°C

Notes 1. Protected.

4. Multiplexed two-wire sensor; after proper address, power/signal bus current indicates magnetic field condition.

3421

AND

3422

HALL-EFFECT,
DIRECTION-DETECTION
SENSORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]

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.