LED drivers for automotive LCD backlights

ROHM has developed LED driver ICs – the BD94130xxx-M series (BD94130MUF-ME2, BD94130EFV-ME2) – for automotive LCD backlights. The devices support large displays increasingly used in next-generation car infotainment and instrument clusters.

In recent years, the advancement of ADAS and expanding car infotainment functionality have initiated a shift towards higher resolution vehicle displays to enhance visibility. As such, LED drivers with a local dimming function able to turn off only the backlight in dark areas of the LCD improve display screen performance and lower power consumption. Automotive manufacturers are now considering them to develop next-generation cockpits. But as the number of zones controlled with conventional direct-type LED drivers by a single IC is lower than 100, the number of LED drivers and peripheral components will also grow as automotive displays become larger with more zones. This represents a notable design challenge.

To meet this need, the company developed products able to control more zones than conventional ICs, making it possible to reduce the mounting area by lowering the number of LED drivers needed. The BD94130xxx-M series of matrix LED drivers combines an eight-line switch controller with a 24-channel current driver – allowing control (dimming) of up to 192 zones mini-LED for backlighting with a single IC. On top of that, the mini-LEDs in each zone can be independently adjusted by utilising a local dimming function – contributing to a larger contrast ratio and lower power consumption displays.

The BD94130xxx-M series of matrix LED drivers combines a 24-channel current driver with a switch controller that can be divided into eight lines (Max.). The number of switch controller lines can be chosen from among three patterns (4, 6, or 8) - through register settings, supporting a variety of specifications based on the number of zones and LED current consumption. Also, a built-in feedback control function maintains a constant feedback voltage independent of LED temperature characteristics – lower thermal design man-hours and loss ratio.

Products equipped with local dimming functionality to support a variety of high-contrast automotive displays include electronic mirrors (side/rear view), car infotainment, instrument clusters and HUDs.