Description

The HT7A3942 is a high performance, low cost Current Mode PWM controller for providing necessary feature to implement Off-Line application. By Optimizing for the Energy Star 2.0 spec., the Power Supply Unit (PSU) implemented using the HT7A3942 can satisfy the “Energy Star No-Load Mode” Stand-by Power standard, which is less than 0.3W within all Nameplate Output Power Range of 0~250W. Internally implemented circuits include a trimmed Oscillator for precise frequency control, a temperature-compensated Voltage Reference, Slope Compensation, Leading-Edge Blanking, and a patented Non-Audible Noise Green Mode Control Scheme.

The HT7A3942 features a range of various protection functions such Short-Circuit Protection (SCP, which can also be used for Over-Load Protection, OLP), Cycle-by-Cycle Current Limiting and Under Voltage Lock-Out (UVLO).

Feature

• High performance, low cost current mode PWM controller especially designed for energy star 2.0

• High-Voltage CMOS process with excellent ESD protection (>3KV)

• Very low startup current (<20μA) and operating current

• ±5 trimmed oscillator for precise frequency control

• Non-audible-noise Green Mode control

• LEB (Leading-Edge Blanking) on CS pin

• Internal slope compensation

• Programmable switching frequency

• Internally trimmed reference with UVLO (Under Voltage Lockout)

• Cycle-by-Cycle Current Limiting

• Build-in Short-Circuit-Protection(SCP) for Short-Circuit and Over-Load condition

• 8-Pin SOP package

Applications

• Switching AC-DC adaptor

• Open frames switching power supply

• LCD TV