Recently, Japan semiconductor manufacturer Rohm developed LED backlight driver ICs that incorporate an ultra-compact wafer-level chip scale package (WL-CSP), which are designed for small 1.6- to 4-inch LCDs in portable devices requiring high efficiency for maximum battery life.
All models integrate a charge pump with automatic voltage multiplier switching (x1, x1.5, x2), eliminating the need for an external inductance coil. In addition, UPIC (Uni-Port Interface Control) is utilized to control the 16-stage constant-current driver (0.125mA to 20mA, pseudo-logarithmic curve) with just 1 control line, reducing the number of wires. The ultra-compact package size, coupled with fewer components and wires required, make the ICs suitable for compact, low-profile, applications seeking to minimize size and space, such as mobile phones, solid-state audio players, and Bluetooth headphones.
The new lineup consists of 3 driver IC models, classified by number of LEDs that can be driven. Each is the smallest in its class. The BD1204GWL and BD1206GUL in particular, optimized for backlight driving in 2 to 4 LCDs, feature an advanced circuit layout that enables PWM brightness control in tandem with video playback, simplifying designs while contributing to lower power consumption. In addition, output ripple is controlled, eliminating the need for external noise countermeasures.