The KF9908 Series is a fixed frequency, constant current step-up DC/DC converter ideal for driving LEDs used in backlighting applications on cellular phones, PDAS and digital cameras etc. Output voltage of up to 23V can be derived, and from a 3.2V input six white LED's can be driven in series or alternatively, using a 2.5V input, a network of two parallel legs with three in each may be driven.

Luminance of the LED's is controlled by changing the duty cycle of a PWM signal applied to the CE pin.

In addition, an internal MOSFET with an Rds(on) of 0.80 is used. Allow profile and small board area solution can be achieved using a chip coil and an ultra small ceramic output capacitor (CL) of 0.22uF.

      Features

Input voltage range : 2.5V-6V.

Output voltage range : up to 23V externally set-up reference voltage 0.25V

Oscillation frequency : 1.0MHz.

On resistance : 0.80

Control : PWM control.

Efficiency : 88%(When driving 3 white LEDs in series Vin=3.6V ILED=20mA).

Stand-by Current : ISTB=1.0Ua.

Load capacitor : 0.22uF,ceramic.

Lx limit Current :1.0A

      Application

PDAs，GPSs.

For White LED Drivers.

Mobil phones, PHS.

Digital still cameras.