OB2288

GENERAL DESCRIPTION

OB2288 is a highly integrated current mode PWM controller. With internal maximum 50% duty cycle limit, it is very suitable to be used in large power applications, especially in forward topology.

OB2288 offers comprehensive protection coverage including Cycle-by-Cycle current limiting, internal Power-On Soft Start, VDD Under Voltage Lockout (UVLO), VDD Over Voltage Protection(OVP), VDD Clamp, Gate Clamp, Over Load Protection(OLP), Over Temperature Protection (OTP), Brownout Protection (BOP). OB2288 also features protections against pin open and short conditions on selected pins.

Moreover, an internal 1-second restart timer prevents permanent OLP latch when the supply of the controller is provided by other DC sources. In general applications where supply is self biased by auxiliary winding, this restart timer will never be triggered.

In OB2288, On-Bright proprietary frequency shuffling technique together with soft switching control at the totem pole gate drive output help to lower the system design barrier to achieve good EMI performance.

To meet the increasing stringent standby power requirements at light or no load condition, On-Bright proprietary “Extended Burst Mode” technology eases the system design with high performance and without compromise in audio noise.

OB2288 is offered in SOP-8 and DIP-8 packages.

FEATURES

■ Maximum 50% Duty Cycle Limit

■ AC Line Brownout Detection & Protection (BOP)

■ Latch-off Mode Fault Protection

■ Internal Restart Timer

■ All Pins Floating Protection and RI Short Protection

■ Proprietary Extended Burst Mode Control For Improved Efficiency and Minimum Standby Power Design

■ Audio Noise Free Operation

■ External Programmable PWM Switching Frequency

■ Built-in Frequency Shuffling for Better EMI

■ Internal Leading Edge Blanking

■ High Precision Reference Voltage for OTP and Brownout Protection

■ Power-On Soft Start

■ Internal Synchronized Slope Compensation

■ 1A Peak Current Drive Capability

APPLICATIONS

Offline AC/DC flyback converter for

■ LCD TV/PC Power Supplies

■ Open-Frame SMPS

TYPICAL APPLICATION