NJU6050 Datasheet | New Japan Radio

.. High Efficiency White LED Driver ¢ GENERAL DESCRIPTION The NJU6050 is a high-efficiency white LED driver. It contains a high-efficiency step-up DC/DC converter and an output driver. The IC can output max.28V and drive as many as 8 white LEDs in series with a constant current, which guarantees the LEDs with uniform brightness. The high frequency of the step-up converter permits the use of small, low-profile inductors and capacitors to minimize the footprint in space-conscious applications. The NJU6050also Features low operating voltage of 2.5V and the small package SOT-23 (MTP-5). All of these benefits make the NJU6050 suitable for the battery-powered portable applications such as cellular phones, camcorders, PDAs, etc. ¢ PACKAGE OUTLINE ¢ Features ˜ Drives Up to 8 White LEDs in Series ˜ ˜ ˜ ˜ VSW = 28V, IOUT = 20m A Uses Small Inductor and Capacitors 2.5V to 6.5V Operating Voltage for Step-up Circuits (VDD ) CMOS Technology Package : SOT-23 5 pin (MTP-5) ¢ PIN CONFIGURATION (TOP VIEW) SW VSS FB 1 2 3 SHDNb Ver.2006-03-28 -1- .. ¢ PIN DESCRIPTIONS No. 1 2 3 4 5 SYMBOL SW VSS FB SHDNb VDD TYPE Input Power Input Input Power Switch Terminal Ground Terminal Feedback Terminal Shutdown Terminal Active “L” “L” : Shutdown “H” : Normal Operation Power Supply terminal DESCRIPTION ¢ BLOCK DIAGRAM L1 VIN C1 Bias DC/DC Control + VREF 1.2V RLED VSS VIN ILED VDD SW FB D2 C2 D1 VOUT SHDNb Shutdown circuit ¢ FUNCTIONAL DESCRIPTONS (1) LED Current Control and Resistor R LED Selection The NJU6050 incorporates the LED current control to regulate the LED current (ILED), which is programmed by the feedback resistor (RLED) connected between the FB and the VSS terminals. The reference voltage VREF is internally regulated to 1.2V typical and connected to the positive input of the built-in parator. Formula (1) is used to choose the value of the RLED , as shown below. RLED = VREF I LED --- Formula (1) VREF...