The FSL137MRIN is an integrated Pulse Width Modulation (PWM) controller and SenseFET specifically designed for offline Switched Mode Power Supplies (SMPS) with minimal external components. The PWM controller includes an integrated fixed-frequency oscillator, Line Over-Voltage Protection (LOVP), Under-Voltage Lockout (UVLO), Leading-Edge Blanking (LEB), optimized gate driver, internal soft-start, temperature-compensated precise current sources for loop compensation, and self-protection circuitry.Compared with a discrete MOSFET and PWM controller solution, the FSL137MRIN reduces total cost, component count, size, and weight; while simultaneously increasing efficiency, productivity, and system reliability. This device provides a basic platform suited for cost-effective design of flyback converters.