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Automotive Electronics

Wheel-Speed Sensors Orientation Compatible as Drop-in Solution to Hall-Effect

Allegro MicroSystems announced the release of their latest wheel speed sensor product line. According to the company, the A19250 (see block diagram above) and A19350 wheel speed sensors meet the industry’s requirements from high accuracy GMR to support biased Hall-effect sensor solutions. The A19250 and A19350 use Allegro’s patented GMR technology which boasts industry-leading performance and is orientation compatible as a drop-in solution to Hall-effect.

These devices make Allegro’s wheel speed product line suitable for meeting the demanding requirements in today’s wheel speed applications such as advanced braking systems.

“Allegro remains committed to providing the widest range of wheel speed sensing IC’s to cover all of the market needs,” explained Peter Wells, Speed Sensor Business Unit Director. “We are proud to add these new GMR based products to our family of Hall products to cover Speed or Speed and Direction protocols as well as GMR or Hall transducer benefits, all with the latest in safety features and algorithmic performance.”

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The company designed the A19250 and A19350 GMR-based ICs for use in combination with magnet encoder rings to measure speed and direction information.

A19350 Block diagram

The GMR technology is integrated monolithically with signal processing algorithms, providing enhanced edge repeatability to support the high accuracy requirements of low-level differential magnetic input signals over higher operational air gaps.

GMR technology coupled with differential sensing techniques offers the rejection of interfering, common-mode magnetic fields.

The GMR wheel speed sensor ICs come in a small single-in-line-package (2-pin SIP) with an integrated EMC protection capacitor. The integrated capacitor provides enhanced EMC performance reducing, and in most cases eliminating, the need for external components.

2-pin SIP package

Allegro developed them for functional safety compliance according to ISO 26262 (pending assessment).

Allegro’s Hall-effect-based solutions include the ARS19200, ATS19200, and A19300 wheel speed sensor ICs. The company says that the flexibility of Hall-effect makes back-biasing a breeze.

Whether the target application is a magnetic encoder ring or a ferrous gear, Allegro says that these products offer speed or speed and direction information with high output accuracy.

For additional design-in ease, the ATS19200 is a fully integrated wheel speed sensor with EMC protection and a back-biasing magnet, providing an optimized sensor IC solution for ferrous gear applications.

Features of A19250
  • GMR technology integrates high sensitivity MR (magnetoresistive) sensor elements and high precision BiCMOS circuits on a single silicon IC offering high accuracy, low magnetic field operation.
  • Integrated capacitor in a single over-molded miniature package provides greater EMC robustness
  • SolidSpeed Digital Architecture™ supports advanced digital processing providing highly accurate edge performance in the presence of extreme system-level disturbances.
  • Compatible orientation for Hall replacement
  • Two-wire current source output supporting speed protocol
  • EEPROM offers device traceability throughout the production process.
Features of A19350
  • GMR technology integrates high sensitivity MR (magnetoresistive) sensor elements and high precision BiCMOS circuits on a single silicon integrated circuit, offering high accuracy, low magnetic field operation
  • Integrated capacitor in a single over-molded miniature package provides greater EMC robustness
  • SolidSpeed Digital Architecture supports advanced algorithms, maintaining performance in the presence of extreme system-level disturbances, including vibration immunity capability over the full target pitch
  • Flexible orientation for xMR or Hall replacement
  • ASIL B rating based on integrated diagnostics and certified safety design process
  • Two-wire current source output pulse-width protocol supporting speed, direction, and ASIL
  • EEPROM offers device traceability throughout the production process