應用於通用串列匯流排C型和渦輪加速技術之高壓升降壓直流轉換器

Abstract

最新的通用串列匯流排(USB)C型傳輸線不僅能夠傳輸資料，還能夠進行電力傳送，傳輸的功率範圍可從0.5瓦特5伏特的低電壓到100瓦特20伏特的高電壓範圍，為了支援USB C型所帶來的多功能電力傳輸，給予主要電路供電的轉換器就必須能夠支撐住高達20伏特的高輸入電壓而不燒毀。同時，我們希望轉換器能夠支持Intel的渦輪加速技術，渦輪加速技術能夠讓中央處理器已超越基礎頻率的速度下運作，然而在這樣的高速模式下運作必然需要大量的電力，因此，直流轉換器必須能夠供給高電壓跟大量電流。一言以蔽之，轉換器必須承受高輸入電壓同時具備供給負載高功率的能力，在這兩個條件下，一個升降壓直流轉換器是首選。本篇論文使用電流模式控制升降壓直流轉換器以簡化補償電路並且提供好的負載調節，然而，在高壓的條件下，元件的耐壓會限制電流感測電路和斜率補償的設計。 在這篇論文所提出的直流轉換器能夠操作在輸入電壓和輸出電壓從5伏特到20伏特的情況下，並且能夠輸出60瓦特的功率及最高6安培的電流。為了減少耗電，轉換器只有降壓和升壓兩種模式。此晶片是由Magna 0.18微米製程所製作的並且是操作在1MHz的頻率下。

Recently, the latest Universal Serial Bus type-C connecter not only can transfer data but also deliver power. As mentioned in USB Power Delivery Specification Release 2.0 Version 1.2, USB type-C can deliver power ranged from 0.5W (100mA at 5V) to 100W (5A at 20V). In order to support such input range, the converter must be able to endure up 20V of input voltage. Also, the converter is required to support the latest Intel® turbo boost technology. Turbo boost technology, discussed in an Intel® November 2008 Whit paper, can enable the CPU to run above its base operation frequency in order to draw out more performance when some cores aren’t operating at maximum speed. In the meantime, the processor requires more power to perform at higher speed. Therefore, the DC-DC converter must be able to deliver high power to CPU cores as well. Combining the two condition, the DC-DC converter we need should be able to receive a wide variety of input voltage (5V to 20V) as well as deliver a large power when the CPU need it. Therefore, a buck-boost converter that can step-up and step-down is most suitable. The thesis proposed a current mode buck-boost converter in order to simplify the compensation circuit and have good load regulation at buck/boost mode. However, the current sensing design as well as slope compensation is limited in high voltage condition. In this thesis, we will further discuss high voltage circuit design. The converter this thesis proposed can withstand input/output voltage ranged from 5V to 20V and can transfer 60W maximum power. The load current is up to 6A at buck mode. Only buck mode and boost mode are implemented in order to reduce loss while input and output are at the same voltage. A high voltage current sensing circuit as well as a dynamic slope compensation circuit is implemented. The chip is fabricated with Magna 0.18um process and operated at 1MHz switching frequency.