Diodes introduces automotive standard DC-DC buck converters

     Diodes Incorporated announced the introduction of its AL8843Q and AL8862Q automotive compliant DC-DC buck converters designed to drive single leds and multiple LED strings in and around vehicles. Applications include daytime running lights (DRL), which many manufacturers now offer as standard, as well as fog lights, turn signals, and brake/brake lights.

     When the supply voltage ranges from 4.5V to at least 40V (AL8862Q to 55V), the AL8843Q and AL8862Q can withstand even severe voltage changes, such as load dumps during low start or stop start operations, without any corresponding degradation of the LED drive current.

     A high level of integration provides high performance while minimizing the bill of materials. Both parts use integrated power MOSFETs: 40V/0.2Ω for the AL8843Q and 55V/0.4Ω for the AL8862Q. In addition, the device uses hysteretic mode buck LED driver control, which simplifies the feedback loop and allows engineers to achieve a highly stable buck converter design using only four external components.

     Distinguishing features of the AL8843Q include an input voltage range of 4.5V to 40V and an output current of 3A, while the AL8862Q can operate at an input voltage of 5V to 55V with outputs up to 1A. Both sections support full scale (0% to 100%) PWM dimming, controlled by analog inputs between 0.4V and 2.5V or PWM signals generated by an external microcontroller or host processor. Safety features include overheat protection as well as LED short and open circuit protection. The AL8862Q contains an open drain fault indicator pin that is asserted to be low to report a fault condition.