TI公司的ucc28780是高頻有源鉗位反激控制器，具有自適應控制的全部和部分零電壓開關（ZVS）的初級FET，外接Si或GaN FET的可編時序，開關頻率高達1MHz，可編程自適應突發(fā)控制和待機模式可提高輕負載效率，具有低輸出波紋和減輕可聽見噪音。主要用在筆記本電腦，平板電腦，TV，機頂盒和打印機的高密度AC/DC適配器，USB供電，直接和快速移動充電器，AC/DC或DC/DC輔助電源。本文介紹了UCC28780主要特性，功能框圖和典型應用電路圖。

UCC28780 is a high-frequency active-clamp flybackcontroller that enables high-density AC-to-DC powersupplies that comply with stringent global efficiencystandards such as DoE Level VI and EU CoC V5Tier-2. User programmable advanced control lawfeatures allow performance to be optimized for bothSilicon （Si） and Gallium Nitride （GaN） power FETs.

Direct operation with switching devices that combinedriver and GaN FETs is further enhanced with logiclevelgate signals and enable outputs.

Zero voltage switching （ZVS） is achieved over a wideoperating range with advanced auto-tuningtechniques， adaptive dead-time optimization， andvariable switching frequency control law. Usingadaptive multimode control that changes theoperation based on input and output conditions，UCC28780 enables high efficiency while mitigating.

audible noise. With a variable switching frequency ofup to 1 MHz and accurate programmable over-powerprotection， which provides consistent power forthermal design across wide line range， the size ofpassive components can be further reduced andenable high power density.

UCC28780 works with VDS-sensing synchronousrectifier controllers， such as UCC24612， to achievehigher conversion efficiency and very compactdesigns.

UCC28780主要特性：

? Full and Partial Zero Voltage Switching （ZVS） ofPrimary FET with Adaptive Control

? Programmable Timing for External Si or GaNFETs

? High Switching Frequency up to 1 MHz

? Programmable Adaptive Burst Control andStandby Mode for Light-Load Efficiency with LowOutput Ripple and Audible Noise Mitigation

? Brownout Detection without Direct Line Sensing

? Accurate Programmable Over-Power Protection（OPP） to Support Peak Power Mode

? Fault Protections： Over-Temperature， OutputOver-Voltage， Output Short-Circuit， Over-Current，and Pin Fault

? Direct Interface with Optocoupler Based FeedbackAllows for Dynamically Scalable Output Voltage

? Internal Soft Start

? NTC Thermistor Interface with External Enable

UCC28780應用：

? High-Density AC-to-DC Adapters for Notebook，Tablet， TV， Set-Top Box and Printer

? USB Power Delivery， Direct and Fast MobileChargers

? AC-to-DC or DC-to-DC Auxiliary Power Supply

圖1.UCC28780功能框圖

圖2.UCC28780典型應用電路圖

圖3.UCC28780 45W EVM電路圖