LM5027 Datasheet | National Semiconductor

Description The LM5027 pulse-width modulation (PWM) controller contains all of the features necessary to implement power converters utilizing the Active Clamp / Reset technique. With the active clamp technique, higher efficiencies and greater power densities can be realized pared to conventional catch winding or RDC clamp / reset techniques. Three control outputs are provided: the main power switch control (OUTA), the active clamp switch control (OUTB), and secondary side synchronous rectifier control (OUTSR). The timing between the control outputs is adjustable with external resistors that program internal precision timers. This controller is designed for high-speed operation including an oscillator frequency range up to 1 MHz and total PWM propagation delays less than 50 ns. The LM5027 includes a high-voltage startup regulator with a maximum input voltage rating of 105V. Additional features include Line Under Voltage Lockout (UVLO), separate softstart of main and synchronous rectifier outputs, a timer for hiccup mode current limiting, a precision reference, and thermal shutdown. Features - - - - - - - - - - - - - Voltage-Mode control Line feed-forward PWM ramp Internal 105V rated start-up bias regulator Programmable line Under-Voltage Lockout (UVLO) with adjustable hysteresis Versatile dual mode over-current protection Programmable volt-second limiter Programmable soft-start Programmable synchronous rectifier soft-start and stop Precise 500m V over-current parator Current sense leading edge blanking Programmable oscillator with 1 MHz maximum frequency and synchronization capability Precision 5V reference Programmable time delays between outputs Packages - e TSSOP-20 Typical Application Circuit Simplified Active Clamp Converter © 2009 National Semiconductor Corporation .national. .. Connection Diagram 20-Lead e TSSOP Ordering Information Order Number LM5027MH LM5027MHX Package Type e TSSOP-20 e TSSOP-20 NSC Package Drawing...