High Performance Current Mode PWM Controller
FEATURES
◆ Proprietary “Zero OCP/OPP Recovery Gap” Control
◆ Built-in Soft Start Function
◆ Pins Floating Protection
◆ Very Low Startup Current
◆ High Voltage CMOS Process with Excellent ESD Protection
◆ Frequency Reduction and Burst Mode Control for Energy Saving
◆ Current Mode Control
◆ Built-in Frequency Shuffling
◆ Programmable Switching Frequency
◆ Built-in Synchronous Slope Compensation
◆ Cycle-by-Cycle Current Limiting
◆ Built-in Leading Edge Blanking (LEB)
◆ Constant Power Limiting
◆ Built-in Leading Edge Blanking (LEB)
◆ Constant Power Limiting
◆ 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
SF1530 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.
The IC 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.
SF1530 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), RT Pin Short-to-GND Protection, Gate Clamping, VCC Clamping, Leading Edge Blanking (LEB).
SF1530 is available in SOT23-6, DIP-8 packages.