Elegant single-chip LED driver with integrated Hall-effect switch

Announced as the world’s first LED driver IC that features an integrated Hall-effect switch, the A1569 has been unveiled by Allegro MicroSystems. The device enables compact, elegant, reliable, and fault-tolerant LED lighting with minimal electrical engineering and low component-count and cost. A 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 LED driver features low-noise, 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. This new device complements Allegro Microsystem’s existing portfolios of LED drivers and Hall-effect switches. It is targeted at consumer electronics, white goods, boats, recreational vehicles, motorcycles, and interior and auxiliary automotive lighting applications such as glove boxes, centre consoles, vanity mirrors, trunks/boots, truck beds, etc. 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 over-moulding, 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 -40C to +125C; the ‘E’ option is for industrial and consumer applications that operate from -40C to 85C. Both versions feature a RoHS-compliant, thermally enhanced SOIC-8 surface-mount package (designator ‘LE’), says the company.