Automotive-grade backlight LED driver optimised for LCD panels

At the same time original buck-boost control ensures compatibility with both small and large LCDs using a single driver. This makes it possible to develop a common design of LCD control board suitable for conventional panels along with the latest large-size displays.

In recent years, to improve both visibility and design in the automotive field, LCDs are being used in an increasing number of systems including instrument clusters, head-up displays and car navigation. In addition, larger screen sizes are being demanded. They require a greater number of high brightness LEDs for backlight as well as LED drivers featuring multi-channel operation and advanced dimming features that can prevent flicker effects.

In response to this increasing market need, ROHM has leveraged its industry-leading analogue design technology and incorporated proprietary technologies into its LED drivers to achieve flicker-free operation and to contribute to a common control board design. The BD81A76EFV-M also allows designers to use larger LCD panels in vehicle applications.

“ROHMs new LED driver allows flexibility of design in modern display architectures and ensures backwards compatibility providing cost effectiveness,” said Stefan Drouzas, Product Marketing Manager Automotive Display Products, ROHM Semiconductor.

ROHM will be committed to continuously contribute to technological innovation in the automotive sector by developing products that achieve greater optimisation and energy savings in vehicle systems.

The BD81A76EFV-M incorporates proprietary buck-boost control to provide greater application flexibility in LCD applications. In contrast to conventional 6channels backlight LED drivers utilising only boost control. Although conventional LED drivers are only capable of driving 36 to 60 LEDs (six to ten LEDs/channel), ROHM’s new driver IC expands the range from six to 60 LEDs (one to ten LEDs/channel). This ensures the support of not only larger displays but also small and medium size panels as well using a single driver, contributing to a common design of control board.

Incorporating a constant current driver with low heat generation enables a best-in-class six channels LED current output of 120mA per channel. Unlike conventional four channels products that support LCDs up to eight inches, ROHM’s new driver can accommodate larger panels in the ten to 12” class. In addition, original PWM dimming technology (patent no. 2018-169705) provides a dimming ratio of 10,000:1, improving visibility and greater design flexibility for centre information displays and instrument clusters.

Leveraging analogue design expertise and process technologies allowed ROHM to reduce standby current consumption to just 10µA. This reduces power consumption to less than 1/3 compared with functionally equivalent products featuring a standby current of 40µA (typ.).

In addition to obtaining qualification under the international AEC-Q100 standard for automotive reliability, the BD81A76EFV-M integrates a spread spectrum function as a countermeasure against EMI that allows it to clear CISPR25 noise requirements for vehicle applications. The result is stable operation in automotive systems sensitive to noise.