With the increasing system complexity in the automotive business sector the integration of efficient and low electromagnetic emission (EME) switch mode power supplies (SMPS) is crucial. The main methods to bring down EME and keep high efficiency are to introduce external filters on the input and output sides, to use spread spectrum techniques on the switching frequency and to control the switching activity of output driver in the desired range. This paper presents the concept of output driver implementation with adaptive driver strength control and dead time optimization for high frequency buck converters with external power MOSFETs. The proposed concept allows the following characteristics to be achieved: improved control of switching activity in a closely defined range, efficiency optimization by minimization the body diode forward conduction, reduction of the reverse recovery losses and zero voltage switching. All these can be realized despite the unknown MOSFET technological parameter distribution (propagation on/off delay, gate resistance of the package, Miller gate charge) and the external parameters (temperature, input voltage, load current). The proposed concept was implemented for a 1.2 V output voltage and a 1.8 MHz switching frequency buck converter.
ASJC Scopus subject areas
- Electrical and Electronic Engineering