The KF7409 is a high efficiency monolithic synchronous buck regulator using a constant frequency,current mode architecture. The device is available in an adjustable version and fixed output voltages, such as

1.2V, 15V, 1.8V, etc. Supply current with no load is 300uA and drops to <luA in shutdown. The 2.5V to 6.5V input voltage range makes the KF7409 ideally suited for single Li-lon, two to four AA battery-powered applications.  duty cycle provides low dropout operation, extending battery life in portable systems. PWM pulse skipping mode operation provides very low output ripple voltage for noise sensitive applications.Switching frequency is internally set at 1 .2MHz,allowing the use of small surface mount inductors and capacitors. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with the 0.6V feedback reference voltage. TheKF7409 is available in a small SOT package.

   Features

High Efficiency: Up to 96%

1.2MHz Constant Switching Frequency

1.5A Output Current at VIN=3V

Integrated Main switch and synchronous rectifier.

No Schottky Diode Required

2.5V to 6.5V Input Voltage Range

Output Voltage as Low as 0.6V

Duty Cycle in Dropout

Current: 300μA(input < 4.2V)

Slope Compensated Current Mode Control for

Excellent Line and Load Transient Response

Short Circuit Protection

<luA Shutdown Current

Soft start

Space Saving 5-Pin SOT23 package

   Application

Cellular and Smart Phones

Microprocessors and DSP Core Supplies

Wireless and DSL Modems

PDAs

MP31 MP4 /PMP Player

Digital Still and Video Cameras

Portable Instruments