- Voltage mode control
- Line voltage feed-forward PWM ramp
- Internal 105V rated start-up bias regulator
- Programmable line undervoltage lockout (UVLO) with adjustable hysteresis
- Multifunctional dual-mode overcurrent protection
- Programmable volt-second limiter
- Programmable soft-start
- Programmable synchronous rectifier soft start and stop
- Accurate 500mV overcurrent comparator
- Current sensing leading edge blanking
- Programmable oscillator 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 functions to implement the power converter, utilizing active clamp/reset technology. Active clamping technology, higher efficiency and greater power density, enables clamping/reset techniques compared to traditional catch-up winding or RDC techniques. Three control outputs are provided: primary power switch control (OUTA), active clamp switch control (OUTB), and secondary synchronous rectification control (OUTSR). The time between the control outputs is adjusted with an external resistor, and the scheme is an internal precision timer. The controller is designed for high-speed operation, including an oscillator with a frequency range up to 1 MHz and full PWM propagation delays of less than 50 ns. The LM5027 includes a high voltage start-up regulator with a maximum input voltage class of 105V. Other features include line undervoltage lockout (UVLO), soft-start independent body and synchronous rectifier outputs, hiccup mode current limit, an accurate reference, and a thermal shutdown timer.
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