具寬輸入電壓範圍低切換損耗之雙模式降壓轉換器

A Dual-Mode Buck Converter with Low Switching Loss for Wide Input Voltage Range

鄭博尹(Bo-Yin Cheng)

指導教授 ： 陳中平

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201902306

摘要

本論文的目的是設計出一個新的截止時間控制電路並將它運用在直流直流降壓轉換器，本論文提出的截止時間控制電路可以讓直流直流降壓轉換器在寬輸入電壓範圍皆可以得到較低的切換頻率，藉此降低系統的切換損耗以得到較高的效率。另外在固定輸入電壓的情形針對不同的負載時，也採用了雙模式設計。當電路處於重載時，電路會操作於連續導通模式。當電路處於輕載時，會使用波谷切換技術使電路會持續操作在邊界導通模式而不會進入不連續導通模式，透過降低切換時功率電晶體的跨壓以降低輕載操作時的切換損失。
本次設計的控制晶片是採用TSMC 0.35μm 2P4M CMOS製程，晶片面積為2.174mm2，搭配外加的功率電晶體和被動元件，建構出一個非同步降壓轉換器。本系統的輸入電壓範圍為4.5V~5.4V，輸出電壓為1.8V，輸出電流範圍為0A至1A。根據量測結果，在連續導通模式下，可以在寬輸入電壓範圍達到0.33%效率的提升。在邊界導通模式下，相較於不連續導通模式也可以達到0.25%效率的提升。

關鍵字

切換頻率 ； 截止時間控制 ； 邊界導通模式 ； 波谷切換 ； 雙模式

並列摘要

The purpose of this thesis is to design a new off-time control method and apply it to a DC-DC buck converter. The off-time controlled circuit proposed in this thesis can make the DC-DC buck converter get the lower switching frequency for wide input voltage range. Thereby reducing the switching loss of the system to achieve higher efficiency. In addition, when the input voltage is fixed for different loads, a dual-mode design is also adopted. When the circuit is under heavy load, the circuit operates in continuous-conduction mode. When the circuit is under light load, valley switching technique is used to keep the circuit in boundary-conduction mode without entering discontinuous-conduction mode. The switching loss at light load is reduced by reducing the voltage across the power transistor during switching.
The proposed chip is fabricated using TSMC 0.35μm 2P4M CMOS process with an area of 2.174mm2. With an additional power transistor and passive components, an asynchronous buck converter is constructed. The input voltage range is from 4.5V to 5.4V. The output voltage is 1.8V. The load current range is from 0 to 1A. According to the measurement results, in the continuous-conduction mode, the efficiency can be improved by 0.33% for wide input voltage range. In the boundary-conduction mode, an efficiency improvement of 0.25% can be achieved compared to the discontinuous-conduction mode.

並列關鍵字

Switching frequency ； off-time control ； boundary-conduction mode ； valley switching ； dual mode

參考文獻

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