FAN5307 Datasheet, PDF (1/13 Pages) Fairchild Semiconductor – High-Efficiency Step-Down DC-DC Converter

January 2006
FAN5307
High-Efficiency Step-Down DC-DC Converter
Features
■ 95% Efficiency, Synchronous Operation
■ Adjustable Output Voltage Option from 0.7V to V_IN
■ 2.5V to 5.5V Input Voltage Range
■ Customized Fixed Output Voltage Options
■ Up to 300mA Output Current
■ Fixed Frequency 1MHz PWM Operation
■ High Efficiency Power Save Mode
■ 100% Duty Cycle Low Dropout Operation
■ Soft Start
■ Dynamic Output Voltage Positioning
■ 15µA Quiescent Current
■ Excellent Load Transient Response
■ 5-Lead SOT-23 Package
■ 6-Lead MLP 3x3mm Package
Applications
■ Pocket PCs, PDAs
■ Cell Phones
■ Battery-Powered Portable Devices
■ Digital Cameras
■ Low Power DSP Supplies
General Description
The FAN5307, a high efficiency low noise synchronous
PWM current mode and Pulse Skip (Power Save) mode
DC-DC converter is designed for battery-powered appli-
cations. It provides up to 300mA of output current over a
wide input range from 2.5V to 5.5V. The output voltage
can be either internally fixed or externally adjustable over
a wide range of 0.7V to 5.5V V_IN by an external voltage
divider. Custom output voltages are also available. Con-
tact a Fairchild sales representative for customized out-
put voltage options.
At moderate and light loads pulse skipping modulation is
used. Dynamic voltage positioning is applied, and the
output voltage is shifted 0.8% above nominal value for
increased headroom during load transients. At higher
loads the system automatically switches to current mode
PWM control, operating at 1 MHz. A current mode con-
trol loop with fast transient response ensures excellent
line and load regulation. In Power Save mode, the quies-
cent current is reduced to 15µA in order to achieve high
efficiency and to ensure long battery life. In shut-down
mode, the supply current drops below 1µA. The device is
available in 5-lead SOT-23 and 6-lead MLP 3x3mm
packages.
Typical Application
100
95
90
85
80
75
70
65
0.01
EFFICIENCY vs. LOAD CURRENT
V_OUT = 1.8V
V_IN=2.5V
V_IN=3.6V
V_IN=5.5V
0.1
1
10
100
Load Current [mA]
1000
©2005 Fairchild Semiconductor Corporation
1
FAN5307 Rev. 1.0.4
www.fairchildsemi.com