Ultra-compact high output linear LED driver ICs optimized for automotive apps

Rohm announced the development of an ultra-compact high output linear LED driver IC (BD18336NUF-M) that provides stable lighting even in the event of battery voltage drops on a single chip, making it ideal for a broad range of socket-type LED lamps used in vehicle systems, from DRLs (Daytime Running Lamps) and position lighting to rear lamps.

In the automotive market, vehicle lamps are increasingly adopting LEDs due to their longer life and high-density mounting. Conventional onboard LEDs support various designs and functions by combining numerous electronic components on a modular substrate, and in recent years there is a growing demand for improved maintainability in addition to design. Socket-type LED lamps that can be replaced as easily as LED bulbs have been attracting attention by offering superior maintainability. However, it is difficult to decrease socket size, reducing design flexibility.

In response, ROHM developed a new LED driver IC that enables mounting in ultra-compact socket-type LED lamp circuits while ensuring stable lighting even during drop in battery voltage.

The BD18336NUF-M adopts a current bypass function that prevents LED turn OFF and maintains a brightness of at least 30% at all times by switching the LED current path, even when the battery voltage decreases from 13V to 9V. In addition, a high output of 600mA is achieved in an ultra-compact 3.0mm square package, and mounting area is reduced by approx. 30% over conventional solutions (including the external circuit), making mounting possible on the 10mm square substrates required for small socket-type LED lamps.

Conventional products, when configured without external circuitry, can cause the LED lamps to turn OFF when the battery voltage drops, possibly creating an unsafe situation during vehicle operation. However, ROHM’s new LED driver IC delivers stable lighting while contributing to the greater miniaturization of socket LED lamps. A function for suppressing LED heat generation is also built in that supports white LEDs that typically run hot, allowing them to be used in DRLs and other vehicle lighting systems utilizing white LEDs.