UC3846N

The key features of the UC1846/7 family of control ICs include automatic feed forward compensation, programmable pulse-by-pulse current limiting, automatic symmetry correction in push-pull configuration, enhanced load response characteristics, parallel operation capability for modular power systems, differential current sense amplifier with wide common mode range, double pulse suppression, 500mA (peak) totem-pole outputs, ±1% bandgap reference, under-voltage lockout, soft start capability, shutdown terminal, and 500kHz operation. These features contribute to improved line regulation, enhanced load response characteristics, and a simpler control loop design .

The UC1846 features low outputs in the OFF state, while the UC1847 features high outputs in the OFF state. The UC1847 has a Collector-Emitter Voltage of 40V, Collector Leakage Current of 200µA, Output Low Level of 0.1-0.4V for ISINK=20mA and 0.4-2.1V for ISINK=100mA, Output High Level of 13-13.5V for ISOURCE=20mA and 12-13.5V for ISOURCE=100mA. The UC1847 also has a Rise Time of 50-300ns and a Fall Time of 50-300ns. These differences in output characteristics distinguish the UC1846 from the UC1847.

The purpose of the shutdown terminal in the UC1846/7 ICs is to initiate either a complete shutdown with automatic restart or latch the supply off. This function is available in addition to built-in under-voltage lockout, programmable current limit, and soft start capability. The UC1846 features low outputs in the OFF state, while the UC1847 features high outputs in the OFF state.