GENERAL DESCRIPTION

OB2268/9 is a highly integrated current mode PWM control IC optimized for high performance, low standby power and cost effective offline flyback converter applications in above 20W power level.

PWM switching frequency at normal operation is externally programmable and trimmed to tight range. At no load or light load condition, the IC operates in extended ‘burst mode’ to minimize switching loss. Lower standby power and higher conversion efficiency is thus achieved.

FEATURES

■ Extended Burst Mode Control For Improved

Efficiency and Minimum Standby Power Design

■ Audio Noise Free Operation

■ External Programmable PWM Switching

Frequency

■ Internal Synchronized Slope Compensation

■ Low VIN/VDD Startup Current(4uA) and Low

Operating Current (2.3mA)

■ Leading Edge Blanking on Current Sense Input

■ Complete Protection Coverage With Auto Self

Recovery

o External Programmable Over Temperature

Protection (OTP)

o With or Without On-chip VDD OVP for

Output Over Voltage Protection.

o Under Voltage Lockout with Hysteresis

(UVLO)

o Gate Output Maximum Voltage Clamp (18V)

o Line Compensated Cycle-by-Cycle Over

current Threshold Setting For Constant Output

Current Limiting Over Universal Input Voltage

Range (OCP)

o Over Load Protection. (OLP)

■ On-Bright Proprietary Frequency Shuffling

Technology for Improved EMI Performance

(OB2269 only)

APPLICATIONS

Offline AC/DC flyback converter for

■ Laptop Power Adaptor

■ PC/TV/Set-Top Box Power Supplies

■ Open-frame SMPS

■ Battery Charger