LM5027SQ-1

• Voltage mode control
• Line voltage feedforward PWM ramp
• Internal 105V rated start-up bias regulator
• Programmable line undervoltage lockout (UVLO) with adjustable hysteresis
• Multi-function dual-mode overcurrent protection
• Programmable volt-second limiter
• Programmable soft start
• Programmable synchronous rectifier soft start and stop
• Accurate 500mV overcurrent comparator
• The current sensing should be eliminated at the front edge
• Programmable oscillators with frequency up to 1 MHz and synchronization capability
• Precision 5V reference
• Programmable time delay between outputs

illustrate

The LM5027 Pulse Width Modulation (PWM) controller contains all the necessary features to implement the power converter, utilizing active clamping/reset technology. Active clamping technology, higher efficiency and greater power density, enables clamping/reset techniques compared to traditional catch-up windings or RDCs. Three control outputs are provided: Main Power Switch Control (OUTA), Active Clamp Switch Control (OUTB), and Secondary Side Synchronous Rectification Control (OUTSR). The time between the control outputs is regulated with an external resistor, the scheme's internal precision timer. The controller is designed for high-speed operation and includes an oscillator with a frequency range of up to 1 MHz and a full PWM propagation delay of less than 50 ns. The LM5027 includes a high-voltage start-up regulator with a maximum input level of 105V. Other features include line undervoltage lockout (UVLO), soft-start independent body and synchronous rectifier outputs, hiccup mode current limiting, a precision reference and thermal shutdown timer.