OB2268 – (OB2268 / OB2269) Current Mode PWM Controller

Part Number: OB2268

Function: (OB2268 / OB2269) Current Mode PWM Controller

Manufacturer: Liteon


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OB2268 image

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OB2268 OB2269 Current Mode PWM Controller OB2268/9 is offered in SOP-8 and DIP-8 packages. 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. VDD low startup current and low operating current contribute to a reliable power on startup design with OB2268/9. A large value resistor could thus be used in the startup circuit to minimize the standby power. The internal slope compensation improves system large signal stability and reduces the possible subharmonic oscillation at high PWM duty cycle output. Leading-edge blanking on current sense input removes the signal glitch due to snubber circuit diode reverse recovery. and greatly reduces the external component count and system cost in the design. OB2268/9 offers complete protection coverage with automatic self-recovery feature including Cycle-byCycle current limiting (OCP), over load protection (OLP), over temperature protection (OTP), VDD over voltage protection (OVP) and under voltage lockout (UVLO). The Gate-drive output is clamped to maximum 18V to protect the power MOSFET. Excellent EMI performance is achieved with OnBright proprietary frequency shuffling technique (OB2269 only) together with soft switching control at the totem pole gate drive output. The tone energy at below 20KHZ is minimized in operation. Consequently, audio noise performance is greatly improved. 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 SelfRecovery 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 Overcurrent 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 TYPICAL APPLICATION ©On-Bright Electronics A Liteon Semiconductor Company -1- Confidential V2.1 OB2268 OB2269 Current Mode PWM Controller GENERAL INFORM […]

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OB2268 Datasheet

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