UC1846J/80257

电流模式PWM控制器 Current Mode PWM Controller

DESCRIPON

The UC1846/7 family of control ICs provides all of the necessary features to implement fixed frequency, 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-to-design 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 under-voltage 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, double pulse suppression, deadline adjust capability, and a±1% trimmed bandgap reference. The UC1846 features low outputs in the OFF state, while the UC1847 features high outputs in the OFF state.

FEATURES

• Automatic Feed Forward Compensation

• Programmable Pulse-by-Pulse Current Limiting

• Automatic Symmetry Correction in Push-p 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

• 500kHZ Operation