A3423
Dual Channel Hall Effect Direction Detection Sensor IC
This device is in production, however, it has been deemed Pre-End
of Life. The product is approaching end of life. Within a minimum of
6 months, the device will enter its final, Last Time Buy, order phase.
Date of status change: June 3, 2013
Recommended Substitutions:
For existing customer transition, and for new customers or new appli-
cations, refer to the
A1233.
NOTE: For detailed information on purchasing options, contact your
local Allegro field applications engineer or sales representative.
Allegro MicroSystems, LLC reserves the right to make, from time to time, revisions to the anticipated product life cycle plan
for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. The
information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no respon-
sibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use.
A3423
Dual Channel Hall Effect Direction Detection Sensor IC
Features and Benefits
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Precisely aligned dual Hall elements
Tightly matched magnetic switchpoints
Speed and direction outputs
Individual Hall element outputs (L package)
Fast power-on time
Output short circuit protection
Operation from an unregulated power supply
Wide operating temperature range
Wide operating voltage range
Integrated EMC-ESD protection
Description
The A3423 is a dual-channel Hall-effect sensor IC ideal for
use in speed and direction sensing applications incorporating
encoder ring-magnet targets. The A3423 provides various output
signals that indicate speed and direction of target rotation. The
Hall elements are both photolithographically aligned to better
than 1
μm.
Maintaining accurate displacement between the two
active Hall elements eliminates the major manufacturing hurdle
encountered in fine-pitch detection applications. The A3423 is
a highly sensitive, temperature-stable magnetic device ideal for
use in harsh automotive and industrial environments.
The Hall elements of the A3423 are spaced 1.63 mm apart,
which provides excellent speed and direction information
for small-geometry targets. Extremely low-drift amplifiers
guarantee symmetry between the switches to maintain signal
quadrature. An on-chip regulator allows the use of this device
over a wide operating voltage range of 3.8 to 24 V.
End-of-line trimming of the Hall element switchpoints provides
tight matching capability. The continuous-time nature of the
Hall elements delivers a fast start-up of the device and low
noise.
The A3423 has integrated protection against transients on
the supply and output pins and short-circuit protection on all
outputs.
The A3423 is available in a 4-pin SIP and a plastic 8-pin
SOIC surface mount package (the SOIC version is currently
in development). Both packages are lead (Pb) free, with 100%
matte tin leadframe plating.
Packages
8-pin SOIC (suffix L)
4-pin SIP (suffix K)
Not to scale
Functional Block Diagram
L package only
Output
Current
Limit
Regulator
Power-on
Logic
OUTA
VCC
E1
Direction
Logic
Output
Current
Limit
DIR
Trim
E2
Output
Current
Limit
SPD
Output
Current
Limit
OUTB
GND
L package only
A3423-DS, Rev. 5
A3423
Dual Channel Hall Effect Direction Detection Sensor IC
Selection Guide
Part Number
A3423EK-T
A3423ELTR-T
A3423LK-T
Package
4-pin through hole SIP
8-pin surface mount SOIC
2
4-pin through hole SIP
Packing
1
Bulk bag, 500 pieces/bag
Tape and reel, 3000 pieces/reel
Bulk bag, 500 pieces/bag
Tape and reel, 3000 pieces/reel
T
A
(°C)
–40 to 85
–40 to 150
A3423LLTR-T
8-pin surface mount SOIC
2
1
Contact Allegro for additional packing options.
2
SOIC package currently in development.
Absolute Maximum Ratings
Characteristic
Supply Voltage
Reverse Battery Voltage
Output Off Voltage
Output Sink Current
Magnetic Flux Density
Operating Ambient Temperature
Storage Temperature
Maximum Junction Temperature
Symbol
V
CC
V
RB
V
OUT
I
OUT(SINK)
B
T
A
T
stg
T
J
(max)
Range E
Range L
–40°C to 150°C
Notes
Rating
30
–30
V
CC
30
Unlimited
–40 to 85
–40 to 150
–65 to 165
165
Units
V
V
V
mA
G
ºC
ºC
ºC
ºC
Pin-out Diagrams
Terminal List Table
Number
K
L
1
2
3
4
5
6, 7
8
VCC
DIR
OUTA
SPD
OUTB
NC
GND
Input power supply; tie to GND with bypass capacitor
Output signal indicating direction of target movement
Analog output indicating B at E1 Hall element
Output signal indicating speed of target movement
Analog output indicating B at E2 Hall element
No connection
Ground connection
1
2
–
3
–
–
GND
Name
Description
VCC
DIR
OUTA
SPD
1
2
3
4
8 GND
7 NC
6 NC
5 OUTB
1
VCC
2
DIR
3
SPD
4
4
L Package
K Package
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A3423
Dual Channel Hall Effect Direction Detection Sensor IC
OPERATING CHARACTERISTICS
valid at T
A
= –40°C to 150°C, T
J
≤
T
J
(max), through full operating air gap range, unless otherwise noted
Characteristics
Electrical Characteristics
Supply Voltage
Output Leakage Current
Undervoltage Lockout
Undervoltage Hysteresis
Output Rise Time
Output Fall Time
Supply Current
Low Output Voltage
Output Current Limit
Speed Output Delay*
Power-on Time
Transient Protection Characteristics
Supply Zener Voltage
Output Zener Voltage
Supply Zener Current
Output Zener Current
Reverse Battery Current
Magnetic Characteristics
Operate Point (Channel A and Channel B)
Release Point (Channel A and Channel B)
Hysteresis (Channel A and Channel B)
Operate Symmetry
Release Symmetry
B
OP
B
RP
B
hys
SYM
OP(AB)
SYM
RP(AB)
B
(A)
> B
OP(A)
, B
(B)
> B
OP(B)
B
(A)
< B
OP(A)
, B
(B)
< B
OP(B)
B
OP
– B
RP
B
OP(A)
– B
OP(B)
B
RP(A)
– B
RP(B)
–35
–55
10
–50
–50
15
–15
30
–
–
55
35
60
50
50
G
G
G
G
G
V
Z(sup)
V
Z(out)
I
Z(sup)
I
Z(out)
I
RCC
I
CC
= 17 mA, T
A
= 25°C
I
OUT
= 3 mA, T
A
= 25°C
V
supply
= 30 V, T
A
= 25°C
V
OUT
= 30 V, T
A
= 25°C
V
RCC
= –28 V, T
A
= 25°C
30
30
–
–
–
–
–
–
–
–
–
–
17
3
15
V
V
mA
mA
mA
V
CC
I
OFF
V
CC(UV)
V
CC(hys)
t
r
t
f
I
CC
V
sat
I
OM
t
d
t
ON
All outputs; I
OUT
= 15 mA; B > B
OP(A)
, B > B
OP(B)
All outputs
Delay between direction changing and speed
output transition
B > B
OP
+ 5 G
Lockout (V
CC(UV)
) – Shutdown
C
LOAD
= 20 pF, R
LOAD
= 1 kΩ
C
LOAD
= 20 pF, R
LOAD
= 1 kΩ
Operating, T
J
≤
165°C
All outputs V
OUT
≤
V
CC
(max)
3.8
–
–
–
–
–
3.4
–
30
0.5
–
–
<1
–
0.4
200
300
8.2
210
–
2.5
2
24
10
3.7
–
–
–
14
500
60
5
5
V
μA
V
V
ns
ns
mA
mV
mA
μs
μs
Symbol
Test Conditions
Min.
Typ.
Max.
Units
* Valid only after the first speed (SPD pin) signal transition. First speed signal transition has no delay.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A3423
Dual Channel Hall Effect Direction Detection Sensor IC
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Package Thermal Resistance
Symbol
R
θJA
Test Conditions*
Package K, 1-layer PCB with copper limited to solder pads
Package L, 1-layer PCB with copper limited to solder pads
Package L, 4-layer PCB
*Additional thermal information available on Allegro website.
Value Units
177
140
80
ºC/W
ºC/W
ºC/W
Power Derating Curve
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
20
V
CC(max)
Maximum Allowable V
CC
(V)
Package K
(R
JA
= 177 ºC/W)
1-layer PCB, Package L
(R
JA
= 140 ºC/W)
4-layer PCB, Package L
(R
JA
= 80 ºC/W)
V
CC(min)
40
60
80
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
0
20
Power Dissipation, P
D
(mW)
1-l
(R ayer
JA
= P C
14 B, P
0 º ac
C/ kag
W)
eL
4
(R -lay
er
JA
= PC
80 B
ºC , Pa
/W ck
) ag
e
L
Pac
(R kage K
JA
=
177
ºC/
W)
40
60
80
100
120
Temperature (°C)
140
160
180
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
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