Abstract
Use of electrical devices in automobiles has increased greatly in recent years. For simplification and weight reduction of the electrical wiring system, the negative terminals of the electrical devices are usually connected to common ground lines (chassis) of the automobile. In addition power semiconductor switches called high side switches for driving the electrical devices are connected to the lines on the positive side of a DC power supply (battery).
For the high side switches, it is desirable to use N type MOSFETs (NMOSFETs). Since no inductive element should be contained in the gate drive circuits for the NMOSFETs, it is necessary to adopt voltage boost circuits using switched capacitors to make the gate terminal voltage referred to the ground higher than the DC source voltage while the NMOSFET is in on-state.
This paper presents an approximated analysis of the steady state and transient state characteris-tics of the gate drive circuit with the voltage boost circuit. The obtained results are useful for designing the interface circuits.
Experimental results agree well with the analytical ones and the validity of the approximated analysis is confirmed.
