Programmable unipolar Hall-effect switch has built in diagnostics

Designed with an externally enabled diagnostic function and user-programmable switch points, Allegro MicroSystems, Europe announces a unipolar Hall-effect switch with an externally enabled diagnostic function and user-programmable switch points.

The A1162 has on-chip electromagnetic coils to implement self-test of the sensor’s magnetic and electrical signal chain.  It is designed for systems where precise magnet switch points and safety, reliability, or both, are critical, such as designs required to meet ISO 26262.

In normal operating mode, the device output transistor turns on (output signal switches low) in the presence of sufficient magnetic field. The output transistor switches off (output signal switches high) when the magnetic field is removed. Automotive applications include shift selectors, seat belt buckles and brake sensors.

When the diagnostic feature is enabled, the output provides a square wave output which confirms the device is properly sensing the internally generated magnetic field. This either eliminates the need for redundant sensors in safety-critical applications or increases robustness in safety-critical applications that might otherwise require redundant sensors – drive-by-wire systems, for example, says the company.

The monolithic IC integrates a voltage regulator, Hall voltage generator, small-signal amplifier, chopper stabilisation, Schmitt trigger, and short-circuit-protected open-collector output able to sink up to 25mA. The on-board regulator permits operation with supply voltages of 3.8 to 24V. It is temperature-stable and stress-resistant, making it suitable for operation over temperatures up to 150ºC. This high-temperature performance is made possible through dynamic offset cancellation techniques, which reduce the residual offset voltage normally caused by device over-moulding, temperature dependencies, and thermal stress. The switch is available in an 8pin eTSSOP.


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