OB2287

GENERAL DESCRIPTION

OB2287 is a highly integrated current mode PWM controller for medium to large offline power converter applications.

Brownout Detection and Shutdown Protection (BOP) is a standard protection feature to OB2287.OB2287 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). OB2287 also features protections against pin open and short conditions on selected pins.

On-Bright proprietary OCP compensation scheme monitors PWM duty cycle and adjusts OCP threshold accordingly at CCM or DCM mode to achieve constant output power limiting across universal AC input. Moreover, an internal 1-second restart timer prevents permanent OLP latch when the supply of the controller is provided by other DC sources. In applications where supply is self biased by auxiliary winding, this restart timer will not be triggered.

On-Bright proprietary frequency shuffling technique in OB2287 helps to lower the system design barrier to achieve good EMI performance together with soft switching control at the totem pole gate drive output.

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

OB2287 is offered in SOP-8 and DIP-8 packages.

 

FEATURES

■   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

■   Proprietary OCP Compensation for Universal AC Input Range

■   High Precision Reference Voltage for OTP and Brownout Protection

■   Power-On Soft Start

■   Internal Synchronized Slope Compensation

■   1A Peak Current Drive Sink Capability

 

APPLICATIONS

Offline AC/DC flyback converter for

■   Printer

■   Adaptor

■   LCD Monitor/TV/PC/Set-Top Box Power Supplies

■   Open-frame SMPS

 

TYPICAL APPLICATION

Typical Flyback   Circuit	Typical Forward   Circuit