A1425: High Accuracy Analog Speed Sensor IC with Integrated Filter Capacitor and Dual Zero-Crossing Output Signal

The A1425 AC-coupled Hall-effect sensor IC is a monolithic integrated circuit that switches in response to changing differential magnetic fields created by rotating ring magnets and, when coupled with a magnet, by ferrous targets. The device is a true zero-crossing detector: the output switches precisely when the difference in magnetic field strength between the two Hall elements is zero. A unique dual-comparator scheme provides for accurate switching at the zero crossing on both the positive and negative-going regions of the differential signal, while utilizing hysteresis to prevent false switching. The zero-crossing nature of this device provides excellent repeatability and accuracy for crankshaft applications.

Changes in field strength at the device face, which are induced by a moving target, are sensed by the two integrated Hall transducers. The transducers generate signals that are differentially amplified by on-chip electronics. This differential design provides immunity to radial vibration within the operating air gap range of the A1425, by rejection of the common mode signal. Steady-state magnet and system offsets are eliminated using an on-chip differential band-pass filter. This filter also provides relative immunity to interference from electromagnetic sources.

The device utilizes advanced temperature compensation for the high-pass filter, sensitivity, and Schmitt trigger switchpoints, to guarantee optimal operation to low frequencies over a wide range of air gaps and temperatures.

Each Hall effect digital integrated circuit includes a voltage regulator, two Hall effect elements, temperature compensating circuitry, a low-level amplifier, band-pass filter, Schmitt trigger, and an output driver, which requires a pull-up resistor. The onboard regulator permits operation with supply voltages from 4.0 to 26.5 V. The output stage can switch 20 mA over the full frequency response range of the device, and is compatible with both TTL and CMOS logic circuits.

The device is packaged in a 4-pin plastic SIP. It is lead (Pb) free, with 100% matte tin plated leadframe.

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Astrorep Inc. (Allegro and Sanken Semiconductors, Sanken Power Supplies)
141 John Street, Suite 300
Babylon, NY 11702
Phone: (631)422-2500
Fax: (631)422-2504
Web: www.astrorepinc.com
Email: donna.tweedy@astrorepinc.com

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  • Senses motion of ring magnet or ferrous targets
  • Integrated filter capacitor
  • Wide operating temperature range
  • Operation with magnetic input signal frequency from 20 Hz to 20 kHz
  • Resistant to EMI
  • Large effective air gaps
  • 4.0 to 26.5 V supply operating range
  • Output compatible with both TTL and CMOS logic families
  • Reverse battery protection
  • Resistant to mechanical and thermal stress
  • Accurate true zero crossing switchpoint

The device is packaged in a 4-pin plastic SIP. It is lead (Pb) free, with 100% matte tin plated leadframe.

K SIP 4 pin

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Functional Block Diagram

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Compliant
Part Composition /
RoHS Data
Comments Samples Check
Distributor Stock
A1425LK-T 4-lead SIP -40°C to 150°C -- View Data Contact your
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