UC3845 Application Note

●High Performance Current Mode Controllers

●The UC3844B, UC3845B series are high performance fixed frequency current mode controllers. They are specifically designed for Off−Line and dc−dc converter applications offering the designer a cost−effective solution with minimal external components. These integrated circuits feature an oscillator, a temperaturecompensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET.

●Features

●•Trimmed Oscillator for Precise Frequency Control

●•Oscillator Frequency Guaranteed at 250 kHz

●•Current Mode Operation to 500 kHz Output Switching Frequency

●•Output Deadtime Adjustable from 50% to 70%

●•Automatic Feed Forward Compensation

●•Latching PWM for Cycle−By−Cycle Current Limiting

●•Internally Trimmed Reference with Undervoltage Lockout

●•High Current Totem Pole Output

●•Undervoltage Lockout with Hysteresis

●•Low Startup and Operating Current

●•These Devices are Pb−Free and are RoHS Compliant

●•NCV Prefix for Automotive and Other Applications Requiring Unique Site and Control Change Requirements; AEC−Q100

●Qualified and PPAP Capable