UC3845 Application Note

●The UC3845BD1R2G is a high-performance fixed frequency current-mode Pulse Width Modulation (PWM) Controller specifically designed for off-line and DC to DC converter applications offering the designer a cost-effective solution with minimal external components. It features an oscillator, a temperature compensated reference, high gain error amplifier, current sensing comparator and a high current totem pole output ideally suited for driving a power MOSFET. Also included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle-by-cycle current limiting, a latch for single pulse metering and a flip-flop which blanks the output off every other oscillator cycle, allowing output deadtimes to be programmed from 50 to 70%.

● Trimmed oscillator for precise frequency control

● Automatic feed forward compensation

● Internally trimmed reference with undervoltage lockout

● High current totem pole output

● Undervoltage lockout with hysteresis

● Low startup and operating current