# An 11/1 Switched-Capacitor DC–DC Converter for Low Power from the Mains

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## Abstract

This chapter describes the implementation of a switched-capacitor DC–DC converter to be used as second stage in the two-stage AC–DC system concept, introduced in Chap. 5 The converter is required to perform a large step-down voltage conversion ratio and this from a high-input voltage. Since this converter will be used in a two-stage system, where total efficiency is the result of subsystem efficiency multiplication, efficiency is the most important specification and is targeted to be at least 90 %. The output of the converter is expected to deliver 100 mW at 3.3 V, as provided in the project target specifications of Table 3.1 Other goals, next to the efficiency and output specification, are to obtain a compact solution that is low cost and robust. The targeted combination of high efficiency, high VCR, and high-input voltage in a small-volume SC converter motivates integration of the power switches, control logic, and auxiliary circuits, while keeping the flying capacitors external. This enables larger capacitance with lower parasitics compared to integrated capacitors, necessary to achieve the stringent efficiency specification. Since full monolithic integration is consequently infeasible, focus is shifted to keeping the number of external components to a strict minimum.

## Keywords

High Input Voltage Project Target Specifications Main Converter Capacitor Terminals Supply Rails## References

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