The UC1842A/3A/4A/5A UC2842A/3A/4A/5A UC3842A/3A/4A/5A SLUS224A is an optimized current mode PWM controller for off-line and DC/DC converters. It provides the necessary features to control current mode switched mode power supplies. It has the following improved features: guaranteed start-up current of less than 0.5mA, trimmed oscillator discharge to 8.3mA, and during under voltage lockout, the output stage can sink at least 10mA at less than 1.2V for VCC over 5V.
This document details the features, electrical characteristics, and applications of the Unitrode UC1842A/3A/4A/5A, UC2842A/3A/4A/5A, and UC3842A/3A/4A/5A integrated circuits. These devices are pin-for-pin compatible improved versions of the UC384x family, designed to control current mode switched-mode power supplies with features like low start-up current, automatic feed-forward compensation, and pulse-by-pulse current limiting.
| Output Sink Current (UVLO) | 10mA |
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The maximum duty cycle for the UC1842A and UC1843A is 100%.
The maximum duty cycle for the UC1844A and UC1845A is limited to 50%.