TI 公司的UCC28070是先進的功率因素修正器件，集成了兩個工作在180度反相的PWM。這種PWM交叉工作能降低輸入和輸出紋波電流，使得導電EMI濾波變得更加容易，成本更低。可編程工作頻率從30 kHz 到300 kHz,有極好的效率和多種保護功能，主要用在高效服務器和臺式PC電源，通信整流器，白色家電和工業設備。本文介紹了UCC28070 主要特性，簡化方框圖和功能方框圖，以及采用兩個UCC28070的四相輸出應用框圖，300W交叉PFC預穩壓器參考設計主要指標，控制器電路圖和電源電路圖。

　　UCC28070 300W Interleaved PFC Pre-regulator Design Review (Rev. B)

　　The UCC28070 is an advanced power factor correction device that integrates two pulse-width modulators (PWMs) operating 180 out of phase. This interleaved PWM operation generates substantial reduction in the input and output ripple currents, and the conducted-EMI filtering becomes easier and less expensive. A significantly improved multiplier design provides a shared current reference to two independent current amplifiers that ensures matched average current mode control in both PWM outputs while maintaining a stable, low-distortion sinusoidal input line current.

　　The UCC28070 contains multiple innovations including current synthesis and quantized voltage feed-forward to promote performance enhancements in PF, efficiency, THD, and transient response.

　　UCC28070 主要特性：

　　Interleaved Average Current-Mode PWM Control

　　with Inherent Current Matching

　　Advanced Current Synthesizer Current Sensing for

　　Superior Efficiency

　　Highly-Linear Multiplier Output with Internal Quantized

　　Voltage Feed-Forward Correction for Near-Unity PF

　　Programmable Frequency (30 kHz to 300 kHz)

　　Programmable Maximum Duty-Cycle Clamp

　　Programmable Frequency Dithering Rate and Magnitude

　　for Enhanced EMI Reduction

　　Magnitude: 3 kHz to 30 kHz

　　Rate: Up to 30 kHz

　　External Clock Synchronization Capability

　　Enhanced Load and Line Transient Response through Voltage

　　Amplifier Output Slew-Rate Correction

　　Programmable Peak Current Limiting

　　Bias-Supply UVLO, Over-Voltage Protection, Open-Loop Detection,

　　and PFC-Enable Monitoring

　　External PFC-Disable Interface

　　Open-Circuit Protection on VSENSE and VINAC pins

　　Programmable Soft Start

　　20-Lead TSSOP/SOIC Packages

　　UCC28070 應用：

　　High-Efficiency Server and Desktop Power Supplies

　　TELecom Rectifiers

　　White Goods and Industrial Equipment

　　圖1：UCC28070簡化方框圖

　　圖2：UCC28070功能方框圖

　　圖3：采用兩個UCC28070的四相輸出應用框圖

　　UCC28070 300W交叉PFC預穩壓器參考設計

　　UCC28070 300-W Interleaved PFC Pre-Regulator Design Review

　　In higher power applications to utilize the full line power and reduce line current harmonics PFC Pre-regulators are generally required. In these high power applications interleaving PFC stages can reduce inductor volume and reduce input and output capacitor ripple current. This results in smaller overall magnetic volume and filter capacitor volume increasing the converters overall power density. This is made possible through distributing the power over two interleaved boost converters and the inductor ripple current cancellation that occurs with interleaving, reference [5]. This application note will review the design of a 300W two-phase interleaved power factor corrected (PFC) pre-regulator. This power converter achieves PFC with the use of the UCC28070 interleaved PFC controller, reference。

　　參考設計指標：

　　圖4：典型平均電流模式交叉PFC預穩壓器電路圖

　　圖5：300W原型子板控制器電路圖

　　圖6：300W原型主板電源電路圖