UC3845N

UC3844, UC3845, UC2844, UC2845 High Performance Current Mode Controllers The UC3844, UC3845 series are high performance fixed frequency current mode controllers. They are specifically designed for Off−Line and DC−to−DC converter applications offering the designer a cost effective solution with minimal external components. These integrated circuits feature 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 dead times to be programmed for 50% to 70%. These devices are available in an 8−pin dual−in−line plastic package as well as the 14−pin plastic surface mount (SOIC−14). The SOIC−14 package has separate power and ground pins for the totem pole output stage. The UCX844 has UVLO thresholds of 16 V (on) and 10 V (off), ideally suited for off−line converters. The UCX845 is tailored for lower voltage applications having UVLO thresholds of 8.5 V (on) and 7.6 V (off). Features www.DataSheet4U.com 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 Curr...