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A power interface IC is designed and demonstrated to convert and manage power for a wireless tire pressure sensor node. The IC includes two switched-capacitor DC-DC converters to supply power to the various components of the sensor at their appropriate voltages. The design of the two integrated converters is discussed, including the optimization of capacitors and power transistors. The losses due to parasitic capacitances are analyzed. Two gate drive techniques are used to drive the gates of the floating triple-well transistors. A synchronous rectifier efficiently harvests energy from an electromagnetic shaker and control circuitry regulates the output voltage while minimizing power consumption. The two converters achieve efficiencies of approximately 84% while the synchronous rectifier achieves an efficiency of 88%.