Boost/SEPIC controller enables 50kHz LED-wide PWM dimming in automotive lighting applications

Diodes Incorporated launches a boost/single-ended primary inductance converter (SEPIC) controller for various automotive LED applications. The AL8853AQ is an automotive-compliant and highly integrated boost/SEPIC controller that provides high performance with a reduced bill of materials (BOM) in automotive LED applications including exterior lights, headlamps, head-up displays (HUD), and backlight displays.

Automotive headlamp manufacturers can use SEPIC topology to enable high or low-beam LED array drivers that operate directly from a vehicle’s battery, instead of using the conventional two-stage topology of a boost followed by a buck converter or a full-bridge buck-boost topology. The SEPIC functionality of the AL8853AQ supports cost-effective, simple buck-boost-like topology, which is well-suited for head-up display systems: an increasingly popular feature in automotive designs.

The wide input range (6V to 40V) of the AL8853AQ supports a typical 12V vehicle battery voltage input. Its 200mV feedback reference voltage has ±3% tolerance to maintain tight brightness control while improving efficiency. The fixed 400kHz switching frequency of the AL8853AQ supports low electromagnetic interference (EMI) by using a fundamental frequency outside the medium wave (MW) band. In addition, this controller’s fast (50kHz) pulse width modulation (PWM) to analog dimming mode (100% down to 1%) prevents visible low or high-frequency flickering usually associated with PWM dimming. The AL8853AQ also includes robust protection features to guard against unexpected overvoltage, overcurrent, overtemperature, and diode and inductor short-circuit events.