UC3847

电流模式 PWM 控制器

The UC1846/7 family of control devices 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 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, double-pulse 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.

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Automatic Feedforward Compensation

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Programmable Pulse-by-Pulse Current Limiting

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Automatic Symmetry Correction in Push-Pull

Configuration

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Enhanced Load Response Characteristics

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Parallel Operation Capability for Modular Power

Systems

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Differential Current Sense Amplifier with Wide

Common Mode Range

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Double-Pulse Suppression

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500-mA Peak Totem-pole Outputs

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±1% Band Gap Reference

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Undervoltage Lockout

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Soft-Start Capability

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Shutdown Terminal

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500-kHz Operation