November 2010

© 2009 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FAN5362 • Rev. 1.0.1

FAN5362

3MHz, 500mA / 750mA Synchronous Buck Regulator

Features

3MHz Fixed-Frequency Operation

45µA Typical Quiescent Current

1.80 to 3.6V Fixed Output Voltage

500mA or 750mA Output Current Capability

2.7V to 5.5V Input Voltage Range

Smooth Transitions to/from 100% Duty Cycle

PFM Mode for High Efficiency in Light Load

Best-in-Class Load Transient Response

Best-in-Class Efficiency

Forced PWM and External Clock Synchronization

Internal Soft-Start

Input Under-Voltage Lockout (UVLO)

Thermal Shutdown and Overload Protection

6-Bump WLCSP, 0.4mm Pitch or 6-Lead 2 x 2mm

Ultrathin Molded Leadless Package

Applications

SD Flash Memory Power Supply

RF Transeiver Power

Cell Phones, Smart Phones

Tablets, Netbooks

3G, LTE, WiMAX™, WiBro

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).

Figure 1. Typical Application

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