SF1533 Datasheet | SiFirst Technology

η-Balance TM PWM Power Switch Fixed 50KHz Fsw Features - Built-in 600V Power MOSFET - Proprietary η-Balance TM Control to Boost Light Load Efficiency - Proprietary “Zero OCP/OPP Recovery Gap” Control - Fixed 50KHz Switching Frequency - Built-in Soft Start Function - Very Low Startup Current - Frequency Reduction and Burst Mode Control for Energy Saving - Current Mode Control - Built-in Frequency Shuffling - Built-in Synchronous Slope pensation - Cycle-by-Cycle Current Limiting - Built-in Leading Edge Blanking (LEB) - Constant Power Limiting - Pins Floating Protection - Audio Noise Free Operation - VDD OVP & Clamp - VDD Under Voltage Lockout (UVLO) APPLICATIONS Offline AC/DC Flyback Converter for - AC/DC Adaptors - Open-frame SMPS - Set-Top Box Power Supplies - ATX Standby Power GENERAL DESCRIPTION SF1533 is a high performance, high efficiency, highly integrated current mode PWM power switch for offline flyback converter applications. In SF1533, PWM switching frequency with shuffling is fixed to 50KHz and is trimmed to tight range. When the output power demands decrease, the IC decreases switching frequency based on the proprietary η -Balance TM control to boost power conversion efficiency at the light load. When output power falls below a given value, the IC enters into burst mode and provides excellent efficiency without audio noise. The IC can achieve “Zero OCP/OPP Recovery Gap” using Si First’s proprietary control algorithm. Meanwhile, the OCP/OPP variation versus universal line input is pensated. The IC has built-in synchronized slope pensation to prevent sub-harmonic oscillation at high PWM duty output. The IC also has built-in soft start function to soften the stress on the MOSFET during power on period. SF1533 integrates functions and protections of Under Voltage Lockout (UVLO), VCC Over Voltage Protection (OVP), Cycle-by-cycle Current Limiting (OCP), Pins Floating Protection, Over Load Protection (OLP), VCC Clamping, Leading Edge Blanking...