The LT1952 is a current mode PWM controller optimized to control the forward converter topology, using one primary MOSFET. The LT1952 provides synchronous rectifier control, resulting in extremely high efficiency. A programmable Volt-Second clamp provides a safeguard for transformer reset that prevents saturation. This allows a single MOSFET on the primary side to reliably run at greater than 50% duty cycle for high MOSFET, transformer and rectifier utilization. The LT1952 includes soft-start for controlled exit from shutdown, overcurrent conditions and undervoltage lockout. A precision 100mV current limit threshold, independent of duty cycle, combines with soft-start to provide hiccup short circuit protection. Micropower start-up allows the LT1952 to be efficiently started from high input voltages. Programmable slope compensation and leading edge blanking allow optimization of loop bandwidth with a wide range of inductors and MOSFETs. The LT1952 can be programmed over a 100kHz to 500kHz frequency range and the part can be synchronized to an external clock. The error amplifier is a true op amp, allowing a wide range of compensation networks. The LT1952 is available in a small 16-pin SSOP package.