- Voltage mode control
- Feed-forward PWM ramp
- Internal 105V rated start-up bias regulator
- Programmable input undervoltage lockout (UVLO) adjustable hysteresis
- Multifunctional dual-mode overcurrent protection
- Programmable volt-second limiter and soft-start
- Programmable synchronous rectifier soft start and stop
- Accurate 500mV overcurrent comparator
- Current sensing leading edge blanking
- Programmable oscillator, maximum frequency of 1 MHz and synchronization capability
- Precision 5V reference
- Time delay between programmable outputs
- 70% maximum duty cycle
illustrate
The LM5027A is a variant of the LM5027's active clamped PWM controller function. The LM5027A features differently in that the LM5027A's maximum duty cycle has been reduced from 91% to 71%. In addition, the oscillator timing equation has been modified.
The LM5027A pulse-width modulation (PWM) controller contains the necessary functions to implement the power converter utilizing active clamp/reset technology. With active clamping technology, higher efficiency and greater power density can be achieved than conventional fishing winding or RDC clamp/reset technology. The third is to provide control outputs: main power switch control (OUTA), active clamp switch control (OUTB), and synchronous rectification control (OUTSR) secondary side. The time between the control outputs is adjusted with the program's internal precision timer external resistor. The controller is designed for high-speed operation, including an oscillator with a frequency range of up to 1 MHz and a total PWM propagation delay of less than 50 nanoseconds. The LM5027A includes a high voltage start-up regulator with a maximum input voltage level of 105V. Other features include line undervoltage lockout (UVLO), a separate main synchronous rectification output, hiccup mode current limiting, an accurate reference, and a thermal shutdown timer soft-start.
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