一個應用於可攜式裝置在輸入瞬態有快速飛電容電壓充電校準的三階降壓式轉換器

Abstract

隨著可攜式電子產品的普及，對於高效率、小體積的電源管理晶片的需求日益增長。傳統的降壓式轉換器雖然已能實現不錯的效率，但其在效率和功率密度上仍有更加提升的空間。近年來的文獻中，混合型轉換器被廣泛研究，結合不同種類的傳統轉換器，使其兼具各自的優點。 三階降壓型轉換器是一種混合型轉換器，結合了切換式電容與切換式電感轉換器，優化功率密度以及使其效率在一些操作條件下優於傳統降壓式轉換器。然而，其架構中的飛電容電壓需要穩在一半的輸入電壓值，才能達到上述提及的優點。過去文獻有提出調節飛電容電壓的控制方法，然而在輸入瞬態發生時，飛電容電壓的反應時間會需要幾個操作週期。這在轉換器操作在不連續導通模式而周期延長的情況下，飛電容電壓的反應時間也會因而延長。 本論文提出了一款應用於可攜式電子裝置，使用漣波調變定導通時間控制的三階降壓型轉換器，並融入了快速飛電容電壓充電校準技術，該技術將電容偵測電路和充電機制納入控制策略中。當穿戴式裝置的輸入電壓從鋰離子電池切換至充電器時，在飛電容尚未穩至新的輸入電壓的一半時，電力級的開關會因此超過額定電壓，造成可靠性問題。而透過本論文提出的快速飛電容電壓充電校準控制方法，能使其在瞬態反應發生時，快速校準飛電容電壓。 此晶片透過台積電0.18μm 1P6M Mixed Signal CMOS製程實現，根據實驗結果，在輸出負載為20毫安培(mA)時，輸入電壓從2.8伏切換至5伏的輸入瞬態發生時，飛電容電壓的暫態反應時間小於20μs，優於未使用快速飛電容電壓充電校準方法時的暫態響應時間3000μs。本晶片輸入電壓為2.8到5伏，輸出電壓操作在1伏，負載電流範圍從1毫安培(mA)到500毫安培(mA)，最高效率在輸入電壓3伏且負載為100毫安培(mA)時為94.8%，提出的控制方法有效的減少輸入切換時的飛電容電壓的暫態反應時間，改善了系統的可靠度。

With the growth of portable electronic devices, the demand for high-efficiency, compact power management ICs has surged. While traditional buck converters have achieved commendable efficiency, there remains room for improvement in both efficiency and power density. In recent years, hybrid converters, combining different types of traditional converters, have been extensively researched, utilizing the benefits of each. Three-level buck converter, a hybrid converter combining Switched-Capacitor and Switched-Inductor converters, optimizes power density and exhibits better efficiency under certain operating conditions compared to conventional buck converters. Its flying capacitor voltage ( ) must stabilize at half of the input voltage for the advantages to be realized. Previous works of literature have proposed control methods to regulate . However, the settling time of requires a few cycles when a line transient occurs. In cases where the converter's operating cycle is prolonged in Discontinuous Conduction Mode (DCM), the transient response time of also increases. This thesis proposes a Ripple-based constant on time (RBCOT) controlled Three-Level Buck Converter for portable electronic devices with Fast V_CF Charging Calibration (FVCC) technique, which incorporates a detection circuit and charging mechanism into the control strategy. When transitioning the input voltage from a Li-ion battery to an adaptor in a portable device, the power MOSFETs exceed their rated voltage due to not yet settling to half of the new input voltage. The proposed control method of the FVCC technique in this thesis accelerates the calibration of when a line transient occurs. The proposed chip is fabricated in TSMC 0.18 μm 1P6M Mixed-Signal CMOS process. Experimental results demonstrate that with an output load of 20 mA, when the input voltage switches from 2.8 V to 5 V, the transient response time of is less than 20μs compared to the case without the FVCC technique, where the transient response time was 3000μs. The proposed Three-Level Buck can provide an output voltage of 1 V at the load current range of 1 mA to 500 mA when the input voltage is 2.8 V to 5 V, and achieves a peak efficiency of 94.8% at an input voltage of 3 V and a load current of 100mA. The proposed control method effectively reduces the transient response time of during a line transient, thereby enhancing system reliability.