• Proprietary "η-BalanceTM" to boost light load efficiency
  • Built-in soft start function
  • Proprietary "zero OCP/OPP recovery gap" control
  • All Pins Floating Protection
  • Very Low Startup Current
  • High Voltage CMOS Process with Excellent ESD Protection
  • Frequency Reduction and Burst Mode Control for Energy Saving
  • Programmable switching frequency
  • Current Mode Control
  • Built-in Frequency Shuffling
  • Cycle-by-Cycle Current Limiting
  • Built-in Leading Edge Blanking (LEB)
  • Constant Power Limiting
  • Audio Noise Free Operation
  • 运用

    Offline AC/DC Flyback Converter for
  • AC/DC Adaptors
  • Open-frame SMPS
  • Set-Top Box Power Supplies
  • ATX Standby Power
      • SF1531S is a high performance, low cost, highly integrated current mode PWM controller for offline flyback converter applications. 
        PWM switching frequency with shuffling is externally programmable, which can reduce conduction EMI emission of a power supply. When the output power demands decrease, the IC automatically decreases switching frequency for high power conversion efficiency. When the current set-point falls below a given value, e.g. the output power demand diminishes, the IC enters into burst mode and provides excellent efficiency without audio noise.
        SF1531S can achieve “Zero OCP/OPP Recovery Gap” using SiFirst’s proprietary control algorithm. Meanwhile, the OCP/OPP variation versus universal line input is compensated. 
        The IC has built-in synchronized slope compensation 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.
        SF1531S integrates functions and protections of Under Voltage Lockout (UVLO), VCC Over Voltage Protection (OVP), Cycle-by-cycle Current Limiting (OCP), All Pins Floating Protection, Over Load Protection (OLP), RT Pin Short-to-GND Protection, Gate Clamping, VCC Clamping, Leading Edge Blanking (LEB). 
        SF1531S is available in SOT23-6, DIP-8 packages.