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 FAN400A 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 even 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 voltages, from 90V_AC to 264V_AC.

The FAN400C provides many protection functions. Pulse-by-pulse current limiting ensures constant output current, even if a short circuit occurs. The internal protection circuit disables PWM output if V_DD exceeds 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.

• 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
• V_DD Over-Voltage Protection (Auto Restart)
• 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

General-purpose, switch-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