FAIRCHILD FAN5355 User's Manual

5355 — 1.1A / 1A / 0.8A , 3M z D ig itally P ro ram ab le R eg lato

November 2011

FAN5355 1.1A / 1A / 0.8A, 3MHz Digitally Programmable Regulator Features Description

 93% Efficiency at 3MHz The FAN5355 device is a high-frequency, ultra-fast transient response, synchronous step-down DC-DC converter

 800m A, 1A, or 1.1A Output Current

optimized for low-power applications using small, low-cost  I2C™-Compatible Interface up to 3.4Mbps inductors and capacitors. The FAN5355 supports up to 800m A, 1A, or 1.1A load current.

 6-bit VOUT Programmable from 0.75V to 1.975V

The device is ideal for mobile phones and similar portable

 2.7V to 5.5V Input Voltage Range

applications powered by a single-cell Lithium-Ion battery. With  3MHz Fixed-Frequency Operation an output-voltage range adjustable via I2C™ interface from 0.75V to 1.975V, the device supports low-voltage DSPs and

 Excellent Load and Line Transient Response

processors, core power supplies, and memory modules in  Small Size, 1H Inductor Solution smart phones, PDAs, and handheld computers.  ±2% PWM DC Voltage Accuracy The FAN5355 operates at 3MHz (nominal) fixed switching frequency using either its internal oscillator or an external

 35ns Minimum On-Time SYNC frequency.  High-Efficiency, Low-Ripple, Light-Load PFM During light-load conditions, the regulator includes a PFM

mode to enhance light-load efficiency. The regulator

 Smooth Transition between PWM and PFM

transitions smoothly between PWM and PFM modes with no

 37A Operating PFM Quiescent Current glitches on VOUT. In hardware shutdown, the current

consumption is reduced to less than 200n A.

 Pin-Selectable or I2C™ Programmable Output Voltage

The serial interface is compatible with Fast/Standard and

 On-the-Fly External Clock Synchronization

High-Speed mode I2C specifications, allowing transfers up to

 10-lead MLP (3 x 3mm) or 12-bump CSP Packages 3.4Mbps. This interface is used for dynamic voltage scaling

with 12.5m V voltage steps for reprogramming the mode of Applications operation (PFM or Forced PWM), or to disable/enable the output voltage.

 Cell Phones, Smart Phones

The chip's advanced protection features include short-circuit

 3G, Wi Fi®, Wi MAX™, and Wi Bro® Data Cards protection and current and temperature limits. During a

sustained over-current event, the IC shuts down and restarts

 Netbooks®, Ultra-Mobile PCs

after a delay to reduce average power dissipation into a fault.

 Smart Reflex™-Compliant Power Supply

During startup, the IC controls the output slew rate to minimize  Split Supply DSPs and P Solutions OMAP™, XSCALE™ input current and output overshoot at the end of soft start. The IC maintains a consistent soft-start ramp, regardless of output

 Mobile Graphic Processors (NVIDIA®, ATI)

load during startup.

 LPDDR2 and Memory Modules

The FAN5355 is available in 10-lead MLP (3x3mm) and 12-bump WLCSP packages.

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© 2008 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN5355 • Rev. 1.1.0