LED drivers simplify automotive lighting systems

By Warren Miller, contributing writer

LED lighting is as much a part of our everyday lives as smartphones or social media, although you probably don’t waste nearly as much time on it. Automobiles have been moving toward replacing traditional light bulbs with LEDs for quite a while already, both internally and externally. Diodes Inc. recently announced the debut of its new BCR4xxUQ series of LED drivers for automotive systems. Applications range from external lighting, such as side markers, puddle lighting, and sill plates, to internal lighting, such as dome, ambient lights, instrument clusters, and button backlighting.

The BCR4xxUQ series was developed to provide a flexible, easy-to-use approach for driving low-power LED strings. Each device is capable of outputting a pre-determined, fixed current or an adjustable constant current between 10 mA and 100 mA (BCR401UQ , BCR402UQ , BCR405UQ ), 200 mA (BCR420UQ ), or 350 mA (BCR421UQ ) with ±10% tolerance.

Using a negative temperature coefficient, all devices in the series maintain the long-term integrity and viability of the LEDs by lowering the driver current as the internal temperature increases. This can be a big benefit in automotive applications in which temperatures can be difficult to control, and you don’t want reliability to suffer due to temperature variations.

The linear topology construction virtually eliminates electromagnetic interference, something more common in electric vehicles and complex electronics systems for engine control, motor control, and even on-board entertainment and communications systems.

Different package options are available for all devices as well: the industry standard SOT26, as well as the 0.6-mm low-profile DFN2020 packaging standard. The low-profile package is better suited for edge-lighting applications such as backlighting interior dashboard instruments and GPS and entertainment displays where device height is a hard constraint.

The BCR4xxUQ series is also capable of driving larger LED strings without sacrificing protection from overvoltage transient surges. This is particularly useful in applications in which voltage transients are possible, such as in 12-V automotive supply systems. Each device has a wide operating voltage range of between 1.4 V to 40 V, while limiting power dissipation to no more than 1.7 W, according to the company. In addition, the BCR421UQ can be PWM-dimmed directly from a 3.3-V MCU signal with up to 25 kHz and a duty cycle of 1%.