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. The supply voltage VDD is also used for feedback compensation, to regulate the output voltage without requiring a conventional TL431 and a photo-coupler. A typical output CV/CC characteristic is shown in Figure 1.

Features

■ Linearly Decreasing PWM Frequency

■ Green Mode Under Light-load and Zero-Load Conditions

■ Constant Voltage (CV) and Constant Current (CC) around ±25 without Secondary Side Feedback Circuitry

■ Precise Constant Voltage (CV) at ±5 by Secondary Side Feedback Circuitry

■ Low Startup Current: 8μA

■ Low Operating Current: 3.6mA

■ Leading-Edge Blanking (LEB)

■ 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)

■ Fixed PWM Frequency with Hopping

■ Gate Output Maximum Voltage Clamped at 17V

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