A1642
Two-Wire True Zero-Speed Miniature Differential
Peak-Detecting Sensor IC with Continuous Calibration
FEATURES AND BENEFITS DESCRIPTION
Running mode calibration for continuous optimization The A1642 is an optimized Hall-effect sensing integrated
Single chip IC for high reliability circuit that provides a user-friendly solution for true zero-speed
Internal current regulator for 2-wire operation digital ring-magnet sensing in two-wire applications. This small
Precise duty cycle signal over operating temperature range package can be easily assembled and used in conjunction with
Large operating air gaps a wide variety of target shapes and sizes.
Automatic Gain Control (AGC) for air gap independent
The integrated circuit incorporates dual Hall-effect elements
switchpoints
and signal processing that switches in response to differential
Automatic Offset Adjustment (AOA) for signal processing
magnetic signals created by ring magnet poles. The circuitry
optimization
contains a sophisticated digital circuit to reduce system offsets,
True zero-speed operation
to calibrate the gain for air-gapindependent switchpoints,
Undervoltage lockout
and to achieve true zero-speed operation. Signal optimization
Wide operating voltage range
occurs at power-on through the combination of offset and
Wide-lead package suitable for welding external
gain adjust and is maintained throughout the operating time
components directly to the package leads or for welding
with the use of a running-mode calibration. The running-mode
the device to a leadframe.
calibration allows immunity to environmental effects such as
micro-oscillations of the target or sudden air gap changes.
PACKAGE:
The regulated current output is configured for two-wire
4-pin SIP
applications and the A1642 is ideally suited for obtaining
(Suffix KN)
speed and duty cycle information in ABS (antilock braking
systems). The 1.5 mm spacing between the dual Hall elements
is optimized for fine pitch ring-magnetbased configurations.
For applications requiring sensing of rotating ferrous gears and
targets, refer to the Allegro ATS series of products. The package
Not to scale
is lead (Pb) free, with 100% matte-tin leadframe plating.
Functional Block Diagram
Hall VCC
Gain
Amplifier
Automatic Offset
AOA DAC AGC DAC Internal Regulator
Control
Gain Control
Tracking
Peak Hold
DAC
GND
Test
Test Signals
A1642LKN-DS, Rev. 5 November 16, 2016Two-Wire True Zero-Speed Miniature Differential
A1642
Peak-Detecting Sensor IC with Continuous Calibration
SELECTION GUIDE
Part Number I Range Packing*
CC
A1642LKNTN-I1-T 4.0 mA Low to 16.0 mA High
Tape and reel, 13-inch reel
4000 pieces per reel
A1642LKNTN-I2-T 5.9 mA Low to 16.8 mA High
*Contact Allegro for additional packing options
ABSOLUTE MAXIMUM RATINGS
Characteristic Symbol Notes Rating Units
Supply Voltage V 28 V
CC
Reverse Supply Voltage V 18 V
RCC
Operating Ambient Temperature T Range L 40 to 150 C
A
Maximum Junction Temperature T (max) 165 C
J
Storage Temperature T 65 to 170 C
stg
PINOUT DIAGRAM
TERMINAL LIST TABLE
Number Name Function
1 VCC Connects power supply to chip
2 NC No connection
1 2 3 4
3 Test Float or tie to GND
4 GND Ground connection
Allegro MicroSystems, LLC
2
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com