LM5027ASQ

• Voltage mode control
• Feed PWM ramp before the trip
• Internal 105V rated start-up bias regulator
• Programmable input undervoltage lockout (UVLO) with adjustable hysteresis
• Multi-function dual-mode overcurrent protection
• Programmable voltsecond limiter and soft start
• Programmable synchronous rectifier soft start and stop
• Accurate 500mV overcurrent comparator
• The current sensing should be eliminated at the front edge
• Programmable oscillator, maximum frequency of 1 MHz and synchronization capability
• Precision 5V reference
• Time delay between programmable outputs
• 70% maximum duty cycle

illustrate

This LM5027A is a variant of the LM5027's active clamping PWM controller feature. The LM5027A feature is that the LM5027A maximum duty cycle has decreased from 91% to 71%. In addition, the oscillator timing equation has been modified.

The LM5027A Pulse Width Modulation (PWM) controller contains the necessary features to enable the power converter to utilize active clamping/reset technology. With active clamping technology, higher efficiency and greater power density can be achieved than traditional fishing windings or RDC clamping/reset techniques. The third is to provide control outputs: main power switch control (OUTA), active clamping switch control (OUTB), and synchronous rectification control (OUTSR) secondary side. The time between the control outputs is regulated with the program's internal precision timer external resistance. The controller is designed for high-speed operation and includes an oscillator with a frequency range of up to 1 MHz and a total PWM propagation delay of less than 50 milliseconds. The LM5027A includes a high-voltage start-up regulator with a maximum input level of 105V. Other features include line undervoltage lockout (UVLO), a separate main synchronous rectifier output, current limiting for hiccup mode, a precise reference, and a soft start of a thermal shutdown timer.