FAN5354 Datasheet, PDF (1/14 Pages) Fairchild Semiconductor – 3MHz, 3A Synchronous Buck Regulator

May 2010
FAN5354
3MHz, 3A Synchronous Buck Regulator
Features
ƒ 3MHz Fixed-Frequency Operation
ƒ Best-in-Class Load Transient
ƒ 3A Output Current Capability
ƒ 2.7V to 5.5V Input Voltage Range
ƒ Adjustable Output Voltage: 0.8 to VIN•0.9
ƒ PFM Mode for High Efficiency in Light Load (Forced PWM
Available on MODE Pin)
ƒ Minimum PFM Frequency Avoids Audible Noise
ƒ 270µA Typical Quiescent Current in PFM Mode
ƒ External Frequency Synchronization
ƒ Low Ripple Light-Load PFM Mode with Forced
PWM Control
ƒ Power Good Output
ƒ Internal Soft-Start
ƒ Input Under-Voltage Lockout (UVLO)
ƒ Thermal Shutdown and Overload Protection
ƒ 12-Lead 3x3.5mm MLP
Applications
ƒ Set-Top Box
ƒ Hard Disk Drive
ƒ Communications Cards
ƒ DSP Power
Description
The FAN5354 is a step-down switching voltage regulator that
delivers an adjustable output from an input voltage supply of
2.7V to 5.5V. Using a proprietary architecture with
synchronous rectification, the FAN5354 is capable of
delivering 3A at over 85% efficiency, while maintaining a
very high efficiency of over 80% at load currents as low as
2mA. The regulator operates at a nominal fixed frequency of
3MHz, which reduces the value of the external components
to 470nH for the output inductor and 10µF for the output
capacitor. Additional output capacitance can be added to
improve regulation during load transients without affecting
stability and inductance up to 1.2µH may be used with
additional output capacitance.
At moderate and light loads, pulse frequency modulation
(PFM) is used to operate the device in power-save mode
with a typical quiescent current of 270µA. 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. PFM mode
can be disabled if constant frequency is desired. To avoid
audible noise, the regulator limits its minimum PFM
frequency. The FAN5354 is available in 12-lead 3x3.5mm
MLP package.
Ordering Information
Part Number
FAN5354MPX
Temperature Range
-40 to 85°C
© 2009 Fairchild Semiconductor Corporation
FAN5354 • Rev. 1.0.4
Figure 1. Typical Application
Package
MLP-12, 3x3.5mm
Packing Method
Tape and Reel
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