The UC1846/7 family of control devices provides all of the necessary features to implement fixedfrequency, current-mode control schemes while maintaining a minimum external parts count. The superior performance of this technique can be measured in improved line regulation, enhanced load response characteristics, and a simpler, easier-todesign control loop. Topological advantages include inherent pulse-by-pulse current limiting capability, automatic symmetry correction for push-pull converters, and the ability to parallel power modules while maintaining equal current sharing. Protection circuitry includes built-in undervoltage lockout and programmable current limit, in addition to soft-start capability. A shutdown function is also available, which can initiate either a complete shutdown with automatic restart or latch the supply off. Other features include fully-latched operation, doublepulse suppression, deadline adjust capability, and a ±1% trimmed band gap reference. The UC1846 features low outputs in the OFF state, while the UCx847 features high outputs in the OFF state.