July 2010

© 2009 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FAN7621S • Rev. 1.0.1

FAN7621S

PFM Controller for Half-Bridge Resonant Converters

Features

Variable Frequency Control with 50% Duty Cycle

for Half-bridge Resonant Converter Topology

High Efficiency through Zero Voltage Switching (ZVS)

Fixed Dead Time: 350ns

Up to 300kHz Operating Frequency

Auto-Restart Operation for All Protections with

Protection Functions: Over-Voltage Protection

(OVP), Over-Current Protection (OCP), Abnormal

Over-Current Protection (AOCP), Internal Thermal

Shutdown (TSD)

Applications

PDP and LCD TVs

Desktop PCs and Servers

Adapters

Telecom Power Supplies

Video Game Consoles

Description

The FAN7621S is a pulse frequency modulation

controller

for

high-efficiency

half-bridge

resonant

converters. Offering everything necessary to build a

reliable and robust resonant converter, the FAN7621S

simplifies designs and improves productivity, while

improving performance. The FAN7621S includes a high-

side gate-drive circuit, an accurate current-controlled

oscillator, frequency-limit circuit, soft-start, and built-in

protection functions. The high-side gate-drive circuit has

a common-mode noise cancellation capability, which

guarantees stable operation with excellent noise

immunity.

Using

the

zero-voltage-switching

(ZVS)

technique dramatically reduces the switching losses and

significantly improves efficiency. The ZVS also reduces

the switching noise noticeably, which allows a small-

sized Electromagnetic Interference (EMI) filter.

The FAN7621S can be applied to various resonant

converter topologies; such as series resonant, parallel

resonant, and LLC resonant converters.

Related Resources

AN4151 — Half-Bridge LLC Resonant Converter Design

Using FSFR-Series Fairchild Power Switch (FPS

Ordering Information

Part Number

Operating Junction

Temperature

Package

Packaging

Method

FAN7621SSJ

-40

°C to +130°C

16-Lead, Small Outline Package (SOP)

Tube

FAN7621SSJX

Tape & Reel