The KF9930 is a set-up DC-DC converter that delivers a regulated output current. The device switches at a 1MHz constant frequency,allowing for the use of small value external inductor and ceramic capacitors.
The KF9930 is targeted to be used for driving loads up to 1A from a two-cell alkaline battery. The LED current can be programmed by the external current sense resistor, Rs,connected between the feedback pin (FB) and ground. A low 95mV feedback voltage reduces the power loss in the Rs for better efficiency.During the shutdown mode， the feedback resistor Rs and the load are completely disconnected and the current consumption is reduced to less than 1uA.
Features
LED Power Efficiency: up to 90%
Current Accuracy: +10%
Low Start-_Up Voltage: 0.9V(ILEo= 270mA)
Low Hold Voltage:0.75V(LED = 200mA)
1MHz Switching Frequency
Uses small,，Low Profile Extemal Components
Low RDS(ON) : 100mQ (TYP.)
Open LED Protection
Over Temperature Protection
Packages: SOT-23-6,SOT89-5 Pb-Free Package
Application
White LED Torch (Flashlight)
White L ED Camera Flash
DSC(Digital Still Camera)Flash
Cellular Camera Phone Flash
PDA Camera Flash
Camcorder Torch(Flashlight) Lamp