A Hybrid Structure Dual-Path Step-Down Converter With 96.2% Peak Efficiency Using 250-m $\Omega$ Large-DCR Inductor

A dual-path step-down converter (DPDC) is presented for achieving high power efficiency in the mobile power management ICs (PMICs). Adopting a hybrid structure using one inductor and one flying capacitor, the proposed DPDC supplies a load current via two parallel paths, relieved an intrinsic problem of the conventional buck converter (CBC) topology, which is a significant power loss from a large DCR of the inductor (R_DCR). Therefore, DPDC achieves a high power efficiency and thus also reduces the heating problem, which is another critical issue in the mobile set. Moreover, DPDC can shrink the volume of the PMIC set with a low manufacturing cost by alleviating an RDCR specification of the inductor. In this paper, although a 250 mQ of large R_DCR inductor is used for our measurements, a 96.2% of peak efficiency was achieved and the power loss of total parasitic resistances can be reduced to up to 30% of that of CBC. Moreover, according to our measurement plots, it is verified that DPDC achieves the efficiency notably higher not only in a wide load current (I_LOAD) range but also in a wide conversion ratio (V_OUT/V_IN) range, compared to CBC.

I. Introduction

As the demand for high-performance mobile devices is growing up, the number of functions provided by them is increasing and its hardware specifications are getting higher. Among power management ICs (PMICs) for mobile applications, the step-down converters account for the largest proportion to supply stable power to a number of digital and analog ICs from the battery, such as mobile application processors (APs), display, sensors, DSP, and so on. As a result, many external inductors are embedded in a mobile device.