Abstract
This work presents a self-timed resonant high-voltage (HV) dc–dc converter in HV CMOS silicon-on-insulator (SOI) with a one-step conversion from 100–325 V input down to a 3.3–10 V output, optimized for applications below 500 mW, such as IoT, smart home, and e-mobility. Unlike bulky power modules, the HV converter is fully integrated, including an on-chip power stage, with only one external inductor (10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{H}$ </tex-math></inline-formula> ) and capacitor (470 nF). It reaches a high power density of 752 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , an overall peak efficiency as high as 81%, and a light-load efficiency of 73.2% at 5 V and 50 mW output. HV loss-reduction techniques are presented and experimentally confirmed to offer an efficiency improvement of more than 32%. Integrated HV insulated gate bipolar transistors (IGBTs) are discussed and implemented as an attractive alternative to conventional integrated HV power switches, resulting in ~20% smaller area at lower losses.
Highlights
T HE trend toward higher functionality and decentralization leads to a growing demand for efficient IC-level power conversion from high voltage (HV) of more than 200 V down to below 5 V
Losses caused by parasitic capacitances, such as those at the drain–source and toward substrate are a challenge in fast-switching HV converters for low-power applications
The typical tail current of insulated gate bipolar transistors (IGBTs) is not critical either, due to zero-current switching (ZCS) at turn-off and the missing reverse diode is not required by the presented topology
Summary
T HE trend toward higher functionality and decentralization leads to a growing demand for efficient IC-level power conversion from high voltage (HV) of more than 200 V down to below 5 V. It describes the influence of high input voltages on the efficiency, size, and other design and layout-specific parameters of conventionally used flyback converters, fly-buck converters, multi-level converters, and soft-switching derivatives. Fast switching multi-level-buck converters, as in [6] [Fig. 2 (right)], reduce the inductance size, but the required flying-capacitor value (Cfly) is still large and difficult to integrate at higher voltages. Their light-load efficiency is low and they require complex control circuits.
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