Dell FAIRCHILD FAN5354 3MHz, 3A Synchronous Buck Regulator Owner's Manual
Summary
This high-efficiency FAN5354 synchronous buck regulator provides robust, adjustable step-down voltage conversion up to 3A at a fixed 3MHz frequency. Engineered for demanding applications—including Set-Top Boxes, HDDs, and communications cards—it guarantees superior performance across varying loads using advanced PFM mode technology. The manual offers comprehensive support, detailing pin functions, recommended components (inductors/capacitors), crucial layout guidelines, and electrical specifications needed for professional circuit designers implementing efficient power solutions.
Page 1 Text Content
, 3 ro la to
March 2011
FAN5354 3MHz, 3A Synchronous Buck Regulator
Description
Features
The FAN5354 is a step-down switching voltage regulator that
3MHz Fixed-Frequency Operation
delivers an adjustable output from an input voltage supply of Best-in-Class Load Transient 2.7V to 5.5V. Using a proprietary architecture with synchronous rectification, the FAN5354 is capable of
3A Output Current Capability
delivering 3A at over 85% efficiency, while maintaining a 2.7V to 5.5V Input Voltage Range very high efficiency of over 80% at load currents as low as 2m A. The regulator operates at a nominal fixed frequency of
Adjustable Output Voltage: 0.8 to VIN•0.9
3MHz, which reduces the value of the external components PFM Mode for High Efficiency in Light Load (Forced PWM to 470n H for the output inductor and 10µF for the output Available on MODE Pin) capacitor. Additional output capacitance can be added to improve regulation during load transients without affecting
Minimum PFM Frequency Avoids Audible Noise
stability and inductance up to 1.2µH may be used with 270µA Typical Quiescent Current in PFM Mode additional output capacitance. External Frequency Synchronization At moderate and light loads, pulse frequency modulation (PFM) is used to operate the device in power-save mode
Low Ripple Light-Load PFM Mode with Forced
with a typical quiescent current of 270µA. Even with such a
PWM Control
low quiescent current, the part exhibits excellent transient Power Good Output response during large load swings. At higher loads, the system automatically switches to fixed-frequency control,
Internal Soft-Start
operating at 3MHz. In shutdown mode, the supply current Input Under-Voltage Lockout (UVLO) drops below 1µA, reducing power consumption. PFM mode can be disabled if constant frequency is desired. To avoid
Thermal Shutdown and Overload Protection
audible noise, the regulator limits its minimum PFM 12-Lead 3x3.5mm MLP frequency. The FAN5354 is available in 12-lead 3x3.5mm MLP package.
Applications Set-Top Box Hard Disk Drive Communications Cards DSP Power
Figure 1. Typical Application
Ordering Information Part Number Temperature Range Package Packing Method FAN5354MPX -40 to 85°C MLP-12, 3x3.5mm Tape and Reel
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN5354 • Rev. 1.0.5
Page Summary Contents For Dell FAIRCHILD FAN5354 3MHz, 3A Synchronous Buck Regulator Owner's Manual
Manual Details
| Brand | Fairchild |
|---|---|
| Pages | 14 |
| File Size | 1.02 MB |
| Published | July 10, 2026 |
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Frequently Asked Questions
How does the device achieve high efficiency at light loads?
It uses Pulse Frequency Modulation (PFM) mode with a typical quiescent current of 270µA to operate in power-save mode.
What functionality is indicated by the PGOOD pin?
The Power Good (PGOOD) open-drain pin pulls LOW if the output voltage falls out of regulation or during soft-start.
How can I force the regulator to stay in PWM mode?
By setting the MODE pin HIGH, the device will stay in fixed-frequency Pulse Width Modulation control rather than switching to PFM.
What is the recommended output capacitor for stable operation?
The manual recommends using 10µF, 6.3V, X5R ceramic capacitors (C_OUT) for optimal regulation.