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A3425
A3425DS-Rev. !
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
AB SO LUTE MAX MUM RAT NGS
Supply Voltage, V
CC
.......................................
26.5 V
Reverse-Battery Voltage, V
RCC
........................
–18 V
Output Off Voltage, V
OUTPUT
..............................
V
CC
Output Sink Current, I
OUTPUT(SINK)
.
Internally Limited
Magnetic Flux Density, B..........................
Unlimited
Operating Temperature
Ambient, T
A
, Range E..................
–40oC to 85oC
Range L................
–40oC to 150oC
Maximum Junction, T
J(max)
........................
165oC
Storage Temperature, T
S
..................
–65oC to 170oC
Two matched Hall effect switches on a single substrate
Sensor element spacing approximately 1 mm
Superior temperature stability
3.3 V 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
The A3425 is a dual-output channel, bipolar switch with two separate Hall-effect
sensor circuits, each providing a separate digital output for speed and direction
signal processing capability. Each sensor circuit has its own independent Hall
element, which are photolithographically aligned to better than 1 μm. Maintaining
accurate mechanical location between the two active Hall elements eliminates the
major manufacturing hurdle encountered in
fi
ne-pitch detection applications. The
A3425 is a highly sensitive, temperature-stable magnetic sensing device, which
is ideal for use in ring magnet-based speed and direction systems used in harsh
automotive and industrial environments.
The A3425 monolithic integrated circuit contains two independent Hall effect
switches, located 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 ampli
fi
ers guarantee symmetry between the switches to maintain signal
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 that are symmetrical between the two switches.
The A3425 is available in a plastic 8-pin SOIC surface mount package and a plas-
tic 4-pin SIP, both in two temperature ranges. Each package is available in a lead
(Pb) free version with 100% matte tin plated leadframe.
Ultra-Sensitive Dual-Channel Quadrature Hall-Effect Bipolar Switch
1
2
3
4
8
7
6
5
VCC
OUTPUTA
OUTPUTB
GND
No connection
No connection
No connection
No connection
Package L, 8-pin SOIC
Package K, 4-pin SIP
1
2
3
4
1. VCC
2. OUTPUTA
3. OUTPUTB
4. GND
Features and Bene
fi
ts