A1642 Datasheet, PDF (1/14 Pages) Allegro MicroSystems – Two-Wire True Zero-Speed Miniature Differential Peak-Detecting Sensor IC with Continuous Calibration

A1642
Two-Wire True Zero-Speed Miniature Differential
Peak-Detecting Sensor IC with Continuous Calibration
Features and Benefits
▪ Running mode calibration for continuous optimization
▪ Single chip IC for high reliability
▪ Internal current regulator for 2-wire operation
▪ Precise duty cycle signal over operating temperature range
▪ Large operating air gaps
▪ Automatic Gain Control (AGC) for air gap independent
switchpoints
▪ Automatic Offset Adjustment (AOA) for signal processing
optimization
▪ True zero-speed operation
▪ Undervoltage lockout
▪ Wide operating voltage range
▪ Wide-lead package suitable for welding external
components directly to the package leads or for welding
the device to a leadframe.
Package: 4-pin SIP (Suffix KN)
Not to scale
Description
The A1642 is an optimized Hall effect sensing integrated
circuit that provides a user-friendly solution for true zero-speed
digital ring-magnet sensing in two-wire applications. This small
package can be easily assembled and used in conjunction with
a wide variety of target shapes and sizes.
The integrated circuit incorporates dual Hall effect elements
and signal processing that switches in response to differential
magnetic signals created by ring magnet poles. The circuitry
contains a sophisticated digital circuit to reduce system offsets,
to calibrate the gain for air-gap–independent switchpoints,
and to achieve true zero-speed operation. Signal optimization
occurs at power-on through the combination of offset and
gain adjust and is maintained throughout the operating time
with the use of a running-mode calibration. The running-mode
calibration allows immunity to environmental effects such as
micro-oscillations of the target or sudden air gap changes.
The regulated current output is configured for two-wire
applications and the A1642 is ideally suited for obtaining
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-magnet–based configurations.
For applications requiring sensing of rotating ferrous gears and
targets, refer to theAllegroATS series of products. The package
is lead (Pb) free, with 100% matte tin leadframe plating.
Functional Block Diagram
Hall
Amplifier
Gain
VCC
Automatic Offset
Control
AOA DAC
Tracking
DAC
Peak Hold
AGC DAC
Gain Control
A1642LKN-DS, Rev. 4
Internal Regulator
Test Signals
GND
Test