DESCRIPTION

The TK11850L is a pulse skipping step-up DC-DC converter IC designed for White LED driver applications with the following built in: a very high current switching transistor (400 mA peak), an inductor current limit detector, low voltage reference (Vref = 0.5 V), high speed oscillator, an error comparator, a rectifier diode (for small power output) and an ON/OFF control. The IC works with a very wide operating supply range (2.3 V to 10 V) and the adjustable output voltage can be set as high as 20 V. The device is in the ON state when the EN pin is pulled to a high level. Using the very small TK11850L and a few external components, battery powered systems with LCD displays such as digital cameras and cellular phones can be effectively backlit with white LEDs. The white LEDs are connected in series and driven at a constant current resulting in uniform brightness

and high efficiency.

FEATURES

■ Very High Speed Adjustable OSC (Max 800 kHz)

■ Very Wide Operating Voltage Range (2.3 V to 10 V)

■ Low Loss Detector (Low Reference Voltage: VREF = 0.5 V)

■ Operates with Toko D31FU Miniature Coil (Current Limited by Input Current Sensor)

■ Internal Switching Transistor

■ Internal Diode

■ Active High On / Off Control

■ Available Intensity Control Using EN Pin with PWM Signal

■ Very Small SOT23L-8 Surface Mount Package

APPLICATIONS

■ LED Backlighting and Frontlighting

■ LED Flashlights

■ Step-up DC-DC Converters