A3425
Ultra-Sensitive Dual-Channel Quadrature
Hall-Effect Bipolar Switch
Features and Benefits
Two matched Hall effect switches on a single substrate
Hall element spacing approximately 1 mm
Superior temperature stability
3.3 to 18 V operation
Integrated ESD diode from OUTPUT and VCC pins
to GND
▪
High-sensitivity switchpoints
▪
Robust structure for EMC protection
▪
Solid-state reliability
▪
▪
▪
▪
▪
Description
The A3425 is a dual–output-channel, bipolar switch with each
channel comprising a separate complete Hall-effect circuit with
dedicated Hall element and separate digital output for speed
and direction signal processing capability. The independent
Hall elements (E1 integrated with
OUTPUTA
, and E2 integrated
with
OUTPUTB
) are photolithographically aligned to better
than 1
μm.
Maintaining this accurate mechanical location
between the two active Hall elements eliminates the major
manufacturing hurdle encountered in fine-pitch detection
applications. The A3425 is a highly sensitive, temperature-stable
magnetic device, which is ideal for use in ring magnet-based
speed and direction sensing systems used in harsh automotive
and industrial environments.
The A3425 contains two independent Hall effect switches, and
has a monolithic IC that accurately locates the two Hall elements,
E1 and E2, approximately 1 mm apart. The digital outputs are
90º out of phase so that the outputs are in quadrature, with the
proper ring magnet design. This allows for easy processing of
speed and direction signals. Extremely low-drift amplifiers
guarantee symmetry between the switches to maintain signal
Package: 8 pin SOIC (suffix L), and 4 pin
SIP (suffix K)
Continued on the next page…
Not to scale
Typical Application
V
OUTPUTB
V
OUTPUTA
2
OUTPUTA
V
Supply
100
Ω
1
VCC
A3425
OUTPUTB
3
GND
4
0.1 uF
Using unregulated supply
A3425DS-Rev. 11
A3425
Ultra-Sensitive Dual-Channel Quadrature
Hall-Effect Bipolar Switch
that are symmetrical between the two switches.
The A3425 is available in a plastic 8-pin SOIC surface mount
package (L) and a plastic 4-pin SIP (K), both in two operating
temperature ranges. Each package is available in a lead (Pb) free
version with 100% matte tin plated leadframe.
Description (continued)
quadrature. The patented chopper stabilization technique cancels
offsets in each channel, and provides stable operation over the
operating temperature and voltage ranges. An on-chip regulator
allows the use of this device over a wide operating voltage range.
Post-assembly factory programming provides sensitive switchpoints
Selection Guide
Part Number
A3425EK-T
A3425ELTR-T
2
A3425LK-T
A3425LLTR-T
1
Contact Allegro
2
Variant
Packing
1
Bulk, 500 pieces/bag
13-in. reel, 3000 pieces/reel
Bulk, 98 pieces/bag
13-in. reel, 3000 pieces/reel
Mounting
4-pin SIP through hole
8-pin SOIC surface mount
4-pin SIP through hole
8-pin SOIC surface mount
Ambient, T
A
–40ºC to 85ºC
–40ºC to 150ºC
for additional packing options.
is in production but has been determined to be NOT FOR NEW DESIGN. This classification indicates that sale of the
variant is currently restricted to existing customer applications. The variant should not be purchased for new design applications
because obsolescence in the near future is probable. Samples are no longer available. Status change: May 4, 2009.
Absolute Maximum Ratings
Characteristic
Supply Voltage
Reverse Battery Voltage
Output Off Voltage
Output Sink Current
Magnetic Flux Density
Operating Ambient Temperature
Maximum Junction Temperature
Storage Temperature
Symbol
V
CC
V
RCC
V
OUTPUT
I
OUTPUT(Sink)
B
T
A
T
J
(max)
T
stg
Range E
Range L
Notes
Rating
26.5
–16
V
CC
Internally Limited
Unlimited
–40 to 85
–40 to 150
165
–65 to 170
Units
V
V
V
–
–
ºC
ºC
ºC
ºC
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
2
A3425
Ultra-Sensitive Dual-Channel Quadrature
Hall-Effect Bipolar Switch
Functional Block Diagram
VCC
Programmable
Trim
Regulator
8 Bits
Channel A
4 Bits
Dynamic Offset
Cancellation
Hall
Element
E1
Sample and Hold
OUTPUTA
Low-
Pass
Filter
Output
Drive
Amp
Channel B
4 Bits
Dynamic Offset
Cancellation
Hall
Element
E2
Sample and Hold
OUTPUTB
Low-
Pass
Filter
Output
Drive
Amp
GND
Terminal List Table
Package K
Package L
1
E1
E2
1
2
3
1
2
3
4
4
E1
8
7
6
5
Pin Number
Package K
Package L
1
2
3
4
5-8
Name
VCC
Function
Connects power supply to on-chip voltage regulator
2
3
4
–
OUTPUTA Output from E1 via
fi
rst Schmitt circuit
OUTPUTB Output from E2 via second Schmitt circuit
GND
NC
Terminal for ground connection
No connection
E2
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
3
A3425
Ultra-Sensitive Dual-Channel Quadrature
Hall-Effect Bipolar Switch
OPERATING CHARACTERISTICS
Valid over operating temperature ranges unless otherwise noted; typical data applies to
V
CC
= 12 V, and T
A
= 25ºC
Characteristic
ELECTRICAL CHARACTERISTICS
Supply Voltage
1
Output Leakage Current
Output Rise Time
Output Fall Time
Supply Current
Low Output Voltage
Output Sink Current
Output Sink Current, Continuous
2
Output Sink Current, Peak
3
Chopping Frequency
V
CC
I
OUTPUT(OFF)
t
r
t
f
I
CC(OFF)
I
CC(ON)
V
OUTPUT(ON)
I
OUTPUT(SINK)
I
OUTPUT(SINK)C
I
OUTPUT(SINK)P
f
C
T
J
< T
J(max)
,V
OUTPUT
= 12 V
t < 3 seconds
Operating; T
A
≤
150°C
Either output
C
LOAD
= 20 pF, R
LOAD
= 820
Ω
C
LOAD
= 20 pF, R
LOAD
= 820
Ω
B < B
RP(A)
,B < B
RP(B)
B > B
OP(A)
,B > B
OP(B)
Both outputs; I
OUTPUT(SINK)
= 20 mA; B > B
OP(A)
,
B > B
OP(B)
3.3
–
–
–
–
–
–
–
–
–
–
–
<1
1.8
1.2
3.5
4.0
160
–
–
–
340
18
10
–
–
6.0
6.0
500
20
70
220
–
V
μA
μs
μs
mA
mA
mV
mA
mA
mA
kHz
Symbol
Test Conditions
Min. Typ.
Max
Units
TRANSIENT PROTECTION CHARACTERISTICS
Supply Zener Voltage
Supply Zener Current
4
Reverse-Battery Current
V
Z
I
Z
I
RCC
I
CC
= 15 mA
V
S
= 28 V
V
RCC
= –18 V, T
J
< T
J(max)
28
–
–
33
–
2
37
9.0
15
V
mA
mA
Continued on the next page...
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
4
A3425
Ultra-Sensitive Dual-Channel Quadrature
Hall-Effect Bipolar Switch
OPERATING CHARACTERISTICS (continued)
Valid over operating temperature ranges unless otherwise noted; typical
data applies to V
CC
= 12 V, and T
A
= 25ºC
Characteristic
Symbol
Test Conditions
Min. Typ.
Max
Units
MAGNETIC CHARACTERISTICS, K Package
5
Operate Point: B > B
OP
Release Point: B < B
RP
Hysteresis: B
OP(A)
– B
RP(A)
,
B
OP(B)
– B
RP(B)
Symmetry: Channel A, Channel B,
B
OP(A)
+ B
RP(A)
, B
OP(B)
+ B
RP(B)
Operate Symmetry: B
OP(A)
– B
OP(B)
Release Symmetry: B
RP(A)
– B
RP(B)
B
OP(A)
, B
OP(B)
B
RP(A)
, B
RP(B)
B
HYS(A)
, B
HYS(B)
SYM
A
, SYM
B
SYM
AB(OP)
SYM
AB(RP)
–
–35
5
–40
–30
–30
7
–7
16
–
–
–
35
–
40
40
30
30
G
G
G
G
G
G
MAGNETIC CHARACTERISTICS, L Package
5
Operate Point: B > B
OP
Release Point: B < B
RP
Hysteresis: B
OP(A)
– B
RP(A)
,
B
OP(B)
– B
RP(B)
Symmetry: Channel A, Channel B,
B
OP(A)
+ B
RP(A)
, B
OP(B)
+ B
RP(B)
Operate Symmetry: B
OP(A)
– B
OP(B)
Release Symmetry: B
RP(A)
– B
RP(B)
1
2
B
OP(A)
, B
OP(B)
B
RP(A)
, B
RP(B)
B
HYS(A)
, B
HYS(B)
SYM
A
, SYM
B
SYM
AB(OP)
SYM
AB(RP)
–
–30
5
–35
–25
–25
7
–7
14
–
–
–
30
–
35
35
25
25
G
G
G
G
G
G
When operating at maximum voltage, never exceed maximum junction temperature, T
J(max)
. Refer to power derating curve charts.
Device will survive the current level specified, but operation within magnetic specification cannot be guaranteed.
3
Short circuit of the output to VCC is protected for the time duration specified.
4
Maximum specification limit is equivalent to I
CC(max)
+ 3 mA.
5
Magnetic
fl
ux density, B, is indicated as a negative value for north-polarity magnetic
fi
elds, and as a positive value for south-polarity
magnetic
fi
elds. This so-called algebraic convention supports arithmetic comparison of north and south polarity values, where the
relative strength of the
fi
eld is indicated by the absolute value of B, and the sign indicates the polarity of the
fi
eld (for example, a
–100 G
fi
eld and a 100 G
fi
eld have equivalent strength, but opposite polarity).
EMC
Contact Allegro MicroSystems for EMC performance.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
5
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