OB2353 Low Power Off Line SMPS Switcher

OB2353 combines a dedicated current mode PWM controller with integrated high voltage power MOSFET.

It is optimized for high performance low standby power and cost effective offline flyback converter applications in sub 10W range. OB2353 PWM frequency operates in the fixed and trimmed . At no load or light load the frequency is internal adjusted, 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 OB2353. 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(CS) input removes the signal glitch due to snubber circuit diode reverse recovery and thus greatly reduces the external component count and system cost in the design. OB2353 offers complete protection coverage with automatic self-recovery feature including Cycle-by-Cycle current limiting (OCP), over load protection (OLP), VDD over voltage clamp and under voltage lockout (UVLO). Excellent EMI performance is achieved with On-Bright proprietary frequency shuffling technique together with soft switching control at the totem pole gate drive output. The tone energy at below 20KHZ is minimized in the design and audio noise is eliminated during operation. OB2353 is offered in SOP-8 package.

Features of CB2353

• Optimized for sub 10W Applications

• Single Chip 650V Sense FET Power Switch for Package.

• Soft Start with 4mS

• Frequency shuffling for EMI

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

• Audio Noise Free Operation

• Fixed 50KHZ Switching Frequency

• Internal Synchronized Slope Compensation

• Low VDD Startup Current and Low Operating Current

• Leading Edge Blanking on Current Sense Input

• Good Protection Coverage With Auto Self Recovery

            -VDD Over Voltage Clamp and Under Voltage Lockout with Hysteresis (UVLO)

         -On-Bright Proprietary Line Input Compensated Cycle-by-Cycle Over-current Threshold Setting For Constant Output Power Limiting Over Universal Input Voltage Range.

            -Overload Protection (OLP).

            -Over voltage Protection(OVP)

Applications of OB2353

• Offline AC/DC fly-back converter for

• Battery Charger

• PDA power supplies

• Digital Cameras

• Power Adapter

• Set-Top Box Power Supplies

• Open-frame SMPS