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 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 (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.