Diode Inc.’s LED drivers deliver a flexible approach to driving low-power LED strings in a variety of automotive lighting applications

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 (BCR401UQBCR402UQBCR405UQ), 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.

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