LM5027A

LM5027A www.ti.com SNVS642B – APRIL 2010 – REVISED MARCH 2013 Voltage Mode Active Clamp Controller Check for Samples: LM5027A FEATURES 1 2 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 and Soft- Start Programmable Synchronous Rectifier Soft- Start and Stop Precise 500mV Over-Current Comparator Current Sense Leading Edge Blanking Programmable Oscillator With 1 MHz Maximum Frequency and Synchronization Capability Precision 5V Reference Programmable Time Delays Between Outputs A 70% Maximum Duty Cycle DESCRIPTION The LM5027A is a functional variant of the LM5027 active clamp PWM controller. The functional difference of the LM5027A is that the maximum duty cycle of the LM5027A is decreased from 91% to 71%. In addition, the oscillator timing equation has been modified. The LM5027A 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 compared 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...