A critical-mode (CRM) operation has recently been used for low-to-medium power-level power factor correction (PFC) boost converter circuit. In theory, this circuit provides very good power factor and little distortion. However, in a real circuit, the input current of such operation suffers from significant input current distortion. In this paper, the phenomenon of input current distortion was analyzed, and the cause was traced to the parasitic capacitance of the MOSFET switch. An on-time adjustment control scheme, based on rigorous mathematical analysis, was proposed to overcome this problem. In addition, zero voltage switching (ZVS) operation was incorporated into this new scheme. An implementation of the proposed strategy was also presented. Simulations were conducted to verify the validity of the proposed scheme.

Peak current control (PCC) can be used to achieve adaptive voltage positioning (AVP) in dc power converters for CPU power applications. However, PCC is seldom used because of the problem with output voltage offset from the target load line. A novel high-gain PCC (HGPCC) AVP scheme was recently reported to correct the aforementioned offset problem while retaining the advantages of PCC, such as easy phase-current balancing, inherently cycle-to-cycle protection, and good stability margin. Without an analytical model, however, it is very hard to achieve prescribed characteristics using this complicated scheme. In this paper, a control model and design considerations will be presented for this scheme. Key equations for converter feedback performance and rules for compensating the feedback loop will be presented. The proposed model was experimentally verified.Index Terms-Adaptive voltage positioning (AVP), constant output impedance, dc power converters, peak current control (PCC).

No abstract

No abstract

A single-inductor dual-output (SIDO) buck converter has recently found applications in hand-held battery-powered electronic devices. The circuit operation and the functional interdependencies among basic converter parameters such as dc voltage gains, transistor duty cycles, and load current levels are much more complicated than those of the single-output counterpart. In this paper, a rigorous analysis was conducted to develop dc equations in steadystate operation for SIDO converters. More importantly, from the analysis results, a possibility of a new mode of operation, dubbed "mix-voltage" operation, will be pointed out. In the so-called "mixvoltage" operation, the converter is capable of working even when the input voltage is lower than one of the two output voltages. In the past, a SIDO buck converter has been used for providing "pure-buck" outputs, i.e., both output voltages are lower than the input voltage. Therefore, this possibility not only opens up new applications but also extends the operating battery range in existing applications. Experimental results confirmed the dc equations and the "mix-voltage" conversion of SIDO buck converters.Index Terms-DC-DC power converters, mix-voltage conversion, single-inductor dual-output (SIDO).