A3425
Ultra-Sensitive Dual-Channel Quadrature Hall-Effect Bipolar Switch
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 amplifiers 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.
Package L, 8-pin SOIC
VCC
OUTPUTA
OUTPUTB
GND
1
2
3
4
8
7
6
5
No connection
No connection
No connection
No connection
Package K, 4-pin SIP
1. VCC
2. OUTPUTA
3. OUTPUTB
4. GND
1
2
3
4
ABSOLUTE MAXIMUM RATINGS
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
Features and Benefits
•
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
A3425DS-Rev. !
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
