Industry's First White LED Driver for LCD Backlight Capable of Real-time Video Brightness Adjustment

ROHM has developed the BD6095GUL, the industry's first white backlight LED driver capable of automatic brightness adjustment of LCD backlights based on ambient brightness as well as the brightness of the image signal in real time, alleviating eyestrain, even during extended viewing. A special sensor circuit is included for automatic fine tuning (256 steps) of drive current based on input from an illumination sensor IC, eliminating flicker while decreasing power consumption to 1/3 of conventional white LED drivers without a brightness adjustment function. In addition, the built-in charge pump circuit features a fourth step up ratio (x1.33) that is closer to the forward voltage of white LEDs, mitigating power loss, further reducing power consumption.Ideal for portable devices of all types, including mobile phones, PDAs, portable navigation devices, handheld gaming consoles, and portable audio players, the BD6095GUL is part of an expanding lineup that features real-time brightness control based on the image signal, a x1.33 charge pump circuit, and brightness adjustment based on ambient light, such as the BD6086GU, a multi-function type designed for illumination control, the BD6085GUL, a simple compact version, and the BD6092GU controller that enables easy brightness adjustment when paired with an existing white LED driver.
Sample shipments will begin in October (sample price: 4.3$), with mass production slated for February 2008.

· Main features of the BD6095GUL:

1. Automatic LCD backlight brightness adjustment function based on ambient brightness when connected to an ambient light sensor
2. Superimposition of brightness adjustment via external PWM is possible, enabling backlight brightness control coordinated with the image signal
3. Step-up voltage variation during PWM operation minimized, eliminating external capacitor noise
4. High-efficiency ×1.33 charge pump built in
5. Gain control of the ambient light sensor IC BH1600FVC is automatically performed, allowing for a wide range of brightness measurements
6. 8bit gradation backlight current adjustment (256 levels, 0.1mA steps) ensures flicker-free viewing

New Product Bulletin for White LED Driver for LCD Backlight ｢BD6095GUL｣(PDF:238KB)

· Series Lineup

		BD6095GUL	BD6086GU	BD6085GUL	BD6092GU
	LED Backlight Driver	Max. 5 lamps	Max. 7 lamps	Max. 7 lamps (max. 3 for flash)	-
	LED Flash Driver	1 lamp	-		-
	Automatic Brightness Adjustment	○(LED current DC control)	○ (LED current DC control)	-	○(PWM output)
	Video Coordinated Control	○(PWM input)	○(PWM input, CPU control)	-	○(PWM mixing possible)
	RGB LED Driver	-	Illumination function	-	-
	Charge Pump Step-up Mode	×1/×1.33/×1.5/×2	×1/×1.5/×2	×1/×1.33/×1.5/×2	-
	LDO Regulator	16 level output, 2 channels	2 level output, 2 channels	16 level output, 4 channels	-
	Sensor Interface	Automatic gain control	Automatic gain control	-	Automatic gain control
	Other	-	GPIO 4 channels	-	-
Package		VCSP50L3	VCSP85H4	VCSP50L3	VCSP85H2
Size(mm)		3.75 × 3.75 × 0.55 (max.)	4.5 × 4.5 × 1.0 (max.)	3.3 × 3.3 × 0.55 (max.)	2.8 × 2.8 × 1.0 (max.)

· Glossary

• Charge pump circuit
  An circuit that steps up voltage by combining a capacitor and a switch. Used in power source circuits and driver circuits where output voltage is higher than input voltage.
• Single-segment broadcast
  Japan's terrestrial digital format divides one channel into thirteen “segments,” several of which are bundled to transmit video, audio, and other data. One segment is reserved for mobile communications. This ‘single-segment broadcast' features a bandwidth one-fourth the usual size, enabling only low-resolution QVGA (320 × 240 pixels) sized images to be transmitted.
• Forward voltage
  The minimum necessary voltage for lighting an LED. Varies depending on the type of LED. White LEDs feature a forward voltage current of approximately 3V per lamp (IF = 15mA).
• PWM
  Short for Pulse Width Modulation, a modulating method that changes the pulse duty cycle.
• LDO regulator
  A linear voltage regulator that operates even when the input voltage slightly exceeds the desired output voltage. Features include low loss, low heat generation, and high efficiency.

LED Driver ICs for LCD Backlights