FAN5362 Datasheet, PDF (1/14 Pages) Fairchild Semiconductor – 3MHz, 500mA / 750mA Synchronous Buck Regulator

November 2010
FAN5362
3MHz, 500mA / 750mA Synchronous Buck Regulator
Features
ƒ 3MHz Fixed-Frequency Operation
ƒ 45µA Typical Quiescent Current
ƒ 1.80 to 3.6V Fixed Output Voltage
ƒ 500mA or 750mA Output Current Capability
ƒ 2.7V to 5.5V Input Voltage Range
ƒ Smooth Transitions to/from 100% Duty Cycle
when VIN Drops
ƒ PFM Mode for High Efficiency in Light Load
ƒ Best-in-Class Load Transient Response
ƒ Best-in-Class Efficiency
ƒ Forced PWM and External Clock Synchronization
ƒ Internal Soft-Start
ƒ Input Under-Voltage Lockout (UVLO)
ƒ Thermal Shutdown and Overload Protection
ƒ 6-Bump WLCSP, 0.4mm Pitch or 6-Lead 2 x 2mm
Ultrathin Molded Leadless Package
Applications
ƒ SD Flash Memory Power Supply
ƒ RF Transeiver Power
ƒ Cell Phones, Smart Phones
ƒ Tablets, Netbooks^®, Ultra-Mobile PCs
ƒ 3G, LTE, WiMAX™, WiBro^®, and WiFi^® Data Cards
ƒ Gaming Devices, Digital CamerasDC/DC Micro Modules
Description
The FAN5362 is a 500mA or 705mA, step-down, switching
voltage regulator that delivers a fixed output voltage from
an input voltage supply of 2.7V to 5.5V. Using a proprietary
architecture with synchronous rectification, the FAN5362 is
capable of delivering a peak efficiency of 96%, while
maintaining efficiency over 90% with load currents as
low as 1mA.
This regulator transitions seamlessly into and out of 100%
duty cycle operation when the supply dips to or below the
regulation setpoint and smoothly recovers full regulation
without overshoot when the supply recovers.
The regulator operates at a nominal fixed frequency of
3MHz, which reduces the value of the external components
to 1µH for the output inductor and 4.7µF for the output
capacitor. The PWM modulator can be synchronized to an
external frequency source.
At moderate and light loads, pulse frequency modulation is
used to operate the device in power-save mode with a
typical quiescent current of 45µA. Even with such a low
quiescent current, the part exhibits excellent transient
response during large load swings. At higher loads, the
system automatically switches to fixed-frequency control,
operating at 3MHz. In shutdown mode, the supply current
drops below 1µA, reducing power consumption. For
applications that require minimum ripple or fixed frequency,
PFM mode can be disabled using the MODE pin.
The FAN5362 is available in 6-bump, 0.4mm pitch, Wafer-
Level Chip-Scale Package (WLCSP) and 6-Lead 2 x 2mm
Ultrathin Molded Leadless Package (UMLP).
Trademarks are the property of their respective owners.
© 2009 Fairchild Semiconductor Corporation
FAN5362 • Rev. 1.0.1
Figure 1. Typical Application
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