Marc Fahlenkamp

Comparison of Inductor-Half-Bridge and Class-E resonant topologies for piezoelectric transformer applications

A comparison of Inductor-Half-Bridge (IHB) and Class-E (CLE) resonant converters using piezoelectric transformer (PT) is presented in this paper. The analysis approach is based on state space normalized solutions which allows precise analyzing and comparing the two topologies for different applications with mathematics software. The obtained mathematic results can be directly used to design and to optimize the converter parameters to meet the requirements of specific applications. Two demonstration boards for an offline 2 Watts LED application have been implemented with IHB and CLE resonant converters separately. The experiment results are in a good agreement with the theoretical calculations and conclusions.

Smart universal control IC for high loaded factor resonant converters

This paper presents an adaptive universal control IC with error protection functions for high loaded factor (Q>5) resonant converters as in Piezo-Transformer (PT) applications. It has wide frequency tuning range from 25 to 500 kHz. Duty cycle (Dc) tracking and synchronization (SY) are included to ensure Zero Voltage Switching (ZVS) and to extend the input voltage and output load ranges. Automatic burst mode (BM) recognition is implemented by external resistive adjustment. This control IC can switch among Dc tracking, SY and BM by pin connection identification. The IC has been fabricated with Infineon 0.6 µm B6CA BiCMOS technology. Two demonstration boards for Class E converters with different PTs have been built up to test the controllability and all the functions of the IC.