September 2008

© 2008 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FAN400C • Rev. 1.0.1

Controller without Secondary Feedback (CC)

Features

Linearly Decreasing PWM Frequency

Green Mode Under Light-Load and Zero-Load

Conditions

Constant Current (CC) without Secondary-Feedback

Circuitry

Low Startup Current: 8μA

Low Operating Current: 3.6mA

Leading-Edge Blanking

Constant Power Limit

Universal AC Input Range

Synchronized Slope Compensation

140

°C OTP Sensor with Hysteresis

Cycle-by-Cycle Current Limiting

Under-Voltage Lockout (UVLO)

Fixed PWM Frequency with Hopping

Gate Output Maximum Voltage Clamped at 17V

Small SSOT-6 Package

Applications

General-purpose, switching-mode, power supplies and

flyback power converters, such as:

Battery Chargers for Cellular Phones, Cordless

Phones, PDAs, Digital Cameras, Power Tools

Power Adapters for Ink Jet Printers, Video Game

Consoles, Portable Audio Players

Open-Frame SMPS for TV/DVD Standby and

Auxiliary Supplies, Home Appliances, Consumer

Electronics

Replacement for Linear Transformers and RCC SMPS

PC 5V Standby Power

Description

This highly integrated PWM controller provides several

features to enhance the performance of low-power

flyback converters. To minimize standby power

consumption,

a

proprietary

green-mode

function

provides off-time modulation to linearly decrease the

switching frequency under light-load and zero-load

conditions. This green mode enables the power supply

to meet international power conservation requirements.

Another advantage of the FAN400C is that the typical

startup current is only 8μA, while the typical operating

current can be as low as 3.6mA. A large startup

resistance can be used to achieve higher power

conversion efficiency.

FAN400C integrates a frequency-hopping function

internally to reduce EMI emissions with minimum line

filters.

Built-in

synchronized

slope

compensation

maintains the stability of peak current-mode control.

Proprietary internal compensation ensures constant

output power limiting over a universal range of AC input

The FAN400C provides many protection functions.

Pulse-by-pulse current limiting ensures constant output

current, even if a short circuit occurs. The internal

24.5V. The gate output is clamped at 17V to protect the

power MOS from over-voltage damage. The built-in

over-temperature protection (OTP) function shuts down

the controller at 140

°C with a 30°C hysteresis.

The FAN400C is designed to provide a low-cost total

solution for flyback converters. It is available in a small-

footprint, 6-pin, SSOT-6 package.

Related Resources

AN-6072 — Low-Power, Green-Mode, PWM Flyback

Power Controller without Secondary Feedback

Ordering Information

Part Number

Operating Temperature Range

Package

Eco Status

Packing Method

FAN400CTY

-40

°C to +105°C

SSOT-6

Green

Tape & Reel

FAN400CNY

-40

°C to +105°C

DIP-8

Green

Tube