OB2268/9 is a highly integrated current mode PWMcontrol IC optimized for high performance, lowstandby power and cost effective offline flybackconverter applications in above 20W power level.PWM switching frequency at normal operation isexternally programmable and trimmed to tight range.At no load or light load condition, the IC operates inextended ‘burst mode’ to minimize switching loss.Lower standby power and higher conversionefficiency is thus achieved.VDD low startup current and low operating currentcontribute to a reliable power on startup design withOB2268/9. A large value resistor could thus be usedin the startup circuit to minimize the standby power.The internal slope compensation improves systemlarge signal stability and reduces the possible subharmonicoscillation at high PWM duty cycle output.Leading-edge blanking on current sense inputremoves the signal glitch due to snubber circuit diodereverse recovery. and greatly reduces the externalcomponent count and system cost in the design.OB2268/9 offers complete protection coverage withautomatic self-recovery feature including Cycle-by-Cycle current limiting (OCP), over load protection(OLP), over temperature protection (OTP), VDDover voltage protection (OVP) and under voltagelockout (UVLO). The Gate-drive output is clampedto maximum 18V to protect the power MOSFET.Excellent EMI performance is achieved with On-Bright proprietary frequency shuffling technique(OB2269 only) together with soft switching control atthe totem pole gate drive output.The tone energy at below 20KHZ is minimized inoperation. Consequently, audio noise performance isgreatly improved