The role of power MOSFETs in modern fuel delivery systemsPower MOSFETs are normally used in fuel delivery to switch the injector on/off per commands from the ECU (Engine Control Unit). One MOSFET will be employed for each injector. As fuel delivery systems have evolved, so have the MOSFET's requirements. This has meant that semiconductor companies have been forced to develop new generations of devices that have enhanced performance in a number of key metrics.1. Operating voltage - some MOSFET parameters for direct-injection will be notably higher than for standard injection systems. Direct- injection systems generally require higher pull-in current (in order to get the solenoid operating against high cylinder pressure). This high current must happen quickly (due to limited time available to inject fuel in the engine cycle, which decreases as the RPM rises), therefore a higher voltage rail is required. Direct- injection systems can have railvoltages >100 V (as opposed to around 50 V for standard injection systems). Thus higher voltage MOSFETs need to be specified, along with voltage boost power supply circuits. Piezoelectric injectors also require high voltages to be activated, typically 200 V or above.