UC2844A Datasheet | Unitrode

FEATURES - Optimized for Off-line and DC to DC Converters - Low Start Up Current (<0.5m A) - Trimmed Oscillator Discharge Current - Automatic Feed Forward pensation - Pulse-by-Pulse Current Limiting - Enhanced Load Response Characteristics DESCRIPTION The UC1842A/3A/4A/5A family of control ICs is a pin for pin patible improved version of the UC3842/3/4/5 family. Providing the necessary features to control current mode switched mode power supplies, this family has the following improved features . Start up current is guaranteed to be less than 0.5m A. Oscillator discharge is trimmed to 8.3m A. During under voltage lockout, the output stage can sink at least 10m A at less than 1.2V for VCC over 5V. The difference between members of this family are shown in the table below. - Under-Voltage Lockout With Hysteresis - Double Pulse Suppression - High Current Totem Pole Output - Internally Trimmed Bandgap Reference - 500k Hz Operation - Low RO Error Amp Part # UC1842A UC1843A UC1844A UC1845A UVLO On 16.0V 8.5V 16.0V 8.5V UVLO Off 10.0V 7.9V 10.0V 7.9V Maximum Duty Cycle <100% <100% <50% <50% BLOCK DIAGRAM Note 1: A/B A = DIL-8 Pin Number. B = SO-14 Pin Number. Note 2: Toggle flip flop used only in 1844A and 1845A. SLUS224A - SEPTEMBER 1994 - REVISED APRIL 2002 CONNECTION DIAGRAMS ABSOLUTE MAXIMUM RATINGS (Note 1) Supply Voltage (Low Impedance Source) - - . . . . 30V Supply Voltage (ICC m A) - - - - Self Limiting Output...