DESCRIPTION

This highly integrated PWM controller provides several features to enhance the performance of low-power flyback converters. To minimize standby power consumption, the proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load and zero-load conditions. This green-mode function 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. The typical start-up current is only 8μA, while the typical operating current can be as low as 3.6mA. A large start-up resistance could be used to achieve even higher power conversion efficiency.

FEATURES

■ Linearly decreasing PWM frequency

■ Green-mode under light-load and zero-load conditions

■ Constant voltage (CV) and constant current (CC)

■ No secondary feedback

■ Low start-up 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

■ 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

■ Small SOT-26 package

APPLICATIONS

Low-power flyback power converters, such as:

■ Battery chargers for cellular phones, cordless phones, PDAs, digital cameras, and power tools

■ Power adapters for ink jet printers, video game consoles, and portable audio players

■ Open-frame SMPS for TV/DVD standby and other auxiliary supplies, home appliances, consumer electronics, and PC 5V standby-power

■ Replacements for linear transformers and RCC SMPS