High Efficiency, Eight-String, White LED Driver for LCD Backlight Applications

The ADD5201 is a white LED driver for backlight applications based on high efficiency, current mode, step-up converter tech-nology. It is designed with a 0.15 Ω, 2.9 A internal switch and a pin adjustable operating frequency between 350 kHz and 1 MHz. The ADD5201 contains eight regulated current sources for uniform brightness intensity. Each current source can be driven up to 30 mA.

The ADD5201 drives up to eight parallel strings of multiple series connected LEDs with a ±1.5% current regulation accuracy. The device provides an adjustable LED driving current up to 30 mA for each channel by an external resistor. The ADD5201 provides various brightness control methods. The LED dimming control can be achieved through SMBus and/or pulse-width modulation (PWM) input. Each dimming mode is selectable with two external dimming mode selection pins. The device pro-vides a pin adjustable output dimming frequency range from 200 Hz to 10 kHz.

The ADD5201 operates over an input voltage range of 6 V to 21 V, but the device can function with a voltage as low as 5.4 V. The ADD5201 has multiple safety protection features to prevent damage during fault conditions. If any LED is open or short, the device automatically disables the faulty current regulator. The internal soft start prevents inrush current during startup. A thermal shutdown protection prevents thermal damage.

The ADD5201 is available in a low profile, thermally enhanced, 4 mm × 4 mm × 0.75 mm, 28-lead, RoHS compliant lead frame chip scale package (LFCSP) and is specified over the industrial temperature range of −25°C to +85°C.

APPLICATIONS

* Notebook PCs, UMPCs, and monitor displays

* White LED driver based on inductive boost converter

Integrated 50 V MOSFET with 2.9 A peak current limit

Input voltage range: 6 V to 21 V

Maximum output adjustable up to 45 V

350 kHz to 1 MHz adjustable operating frequency

Built-in soft start for boost converter

* Drives up to eight LED current sources

LED current adjustable up to 30 mA for each channel

Headroom control to maximize efficiency

Adjustable output dimming frequency: 200 Hz to 10 kHz

LED open/short fault protection