Green-Mode PWM Controller with Integrated Protections 

Features

l High-voltage (500V) startup circuit

l Standby 100mW solution

l Current mode PWM

l Very low startup current (<20uA)

l Under-voltage lockout (UVLO)

l Non-audible-noise green-mode control

l Programmable switching frequency

l Cycle-by-cycle peak current limiting

l Internal leading-edge blanking

l Internal slope compensation

l Internal 4ms soft start (Fs = 65KHz)

l Gate output voltage clamp

l Soft driving for reducing EMI

l Over-voltage protection (OVP) on Vcc pin

l Over-load protection (OLP)

l 500mA driving capability

Description

The GR8874 is a highly-integrated, low startup current, current mode PWM controller with green-mode function and high-voltage start up circuit. A high-voltage current source supplies the start up current and the traditional start-up resistor can be saved in order to reduce the power dissipation due to start-up resistor. The controller also includes the leading-edge blanking of the current sensing, internal slope compensation and cycle-by-cycle peak current limiting. It is also integrated soft driving for reducing EMI, gate output voltage clamp function for protecting power MOSFET. GR8874 provides several protections such as OLP, OVP, and OCP for fault conditions. The GR8874 improves the performance and reduces the cost of power supplies. It is available in 8-pin SOP,7-pin SOP and 8-pin DIP package.

Applications

l Open-frame SMPS

l Switching AC/DC adapter

Typical Application Circuit

Package