LED driver integrates Hall-effect switch
The A1569 single silicon chip integrates a Hall plate, a small-signal amplifier, chopper stabilisation, a Schmitt trigger, and a LED driver with soft on/off and short circuit and thermal protection with automatic recovery. The integrated solid-state Hall-effect switch supports silent, sealed, contactless activation and offers a significant upgrade from failure-prone mechanical switches.
The chip features an adjustable, linear drive of up to 150mA into one or more LEDs. An optional external capacitor programs the turn-on/turn-off rate, adding an elegant ‘theatre’ effect. It is controlled by the Hall-effect switch and turns on and off in response to a magnet. The Hall-effect switch is omnipolar (responsive to both North and South magnetic poles) and highly sensitive (BOP = 40G) to support a wide range of mechanical configurations and enclosures with various air-gaps and degrees of mechanical misalignment.
The on-board regulator permits operation with supply voltages of 7 V to 24 V. Reliability and EMC performance are enhanced with Zener clamps, output short-circuit protection, thermal shutdown, and reverse-battery protection. Superior Hall switch performance is made possible through dynamic offset cancellation, which reduces the residual offset voltage normally caused by device overmolding, temperature drift, and thermal stress.
The device is available in two versions: the ‘K’ option is an automotive-grade (AEC-Q100) device that operates from -40 °C to +125 °C; the ‘E’ option is for industrial and consumer applications that operate from -40 °C to 85 °C. Both versions feature a RoHS-compliant, thermally enhanced SOIC-8 surface-mount package (designator ‘LE’).
Visit Allegro MicroSystems at www.allegromicro.com
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