FAN400A: Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Description: This highly integrated PWM controller provides sev...
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. The supply voltage VDD is also used for feedback compensation, to regulate the output voltage without requiring a conventional TL431 and a photo-coupler. 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.
FAN400A 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 90VAC to 264VAC.
The FAN400A 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 VDD exceeds 22.7V. 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 FAN400A is designed to provide a low-cost total solution for flyback converters. It is available in a small-footprint, 6-pin, SOT-26 package.
Linearly Decreasing PWM Frequency
Green Mode Under Light-Load and Zero-Load Conditions
Constant Voltage (CV) and Constant Current (CC)
No Secondary Feedback
Low Startup Current: 8µA
Low Operating Current: 3.6mA
Constant Power Limit
Universal AC Input Range
Synchronized Slope Compensation
140°C OTP Sensor with Hysteresis
VDD Over-Voltage Clamping
Cycle-by-Cycle Current Limiting
Under-Voltage Lockout (UVLO)
Gate Output Maximum Voltage Clamped at 17V
Fixed PWM Frequency with Hopping
Small SOT-26 Package
Wireless LAN Access Point/Router
External AC-DC Merchant Power Supply - Wireless Communications
Technical Documentation & Design Resources
Availability and Samples
Compliance: Pb-free Halide free
Description: Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Package Type: TSOT-23-6
Package Case Outline: 419BL
Container Type: REEL
Container Qty: 3000
Market Leadtime (weeks):2 to 4
VCC Min (V):
VCC Max (V):
fSW Typ (kHz):