DESCRIPTION
The KB4312 step-up converter drives white LEDs with a constant current to provide backlight in cell phones, PDAs, and other hand-held devices. It features allowing series connection of the white LEDs so that the LED currents are identical for uniform brightness. An enable input can be pulsed repeatedly to adjust LED’s brightness. The fast 1.2 MHz current-mode PWM control allows for smaller capacitor and inductor. Fault condition protection uses cycle-by-cycle current limiting to sense maximum inductor current, thermal protection and over-voltage protection. Also included soft-start eliminates inrush current during start-up. The 0.24V low reference voltage minimized the power loss across the current-setting resistor.
The KB4312 is available in SOT23 packages.

FEATURES
• Operating Voltage:2.5V~6.5V
• High Operating Frequency: 1.2MHz
• High Efficiency: Up to 92%
• High Output Voltage: Up to 28V(max)
• Shutdown Current <1μA
• 18V Output Over-voltage protection (ADJ)
• Digital Dimming Control.
• Built-in Cycle-by Cycle Current-limiting.
• Built-in Soft-Start Function.
• 0.24V Low Reference Voltage(+/-5%)
• Tiny SOT23 Package

APPLICATIONS
• LED Module
• LED Backlight for LCD Display (1" ~6.5")
• Constant Current Source!