Powering the Car of the Future Today
Cars need more compact, efficiently packaged MOSFETs that handle increased power requirements, remove weight, and free up space in vehicle’s electrical system.
Cars are growing. Not necessarily always in terms of physical size, but certainly in the complexity and capability of on-board technology and equipment. For the car buyer this provides a qualitative improvement in driving experience and for manufactures this trend offers new areas in which to compete with new and revolutionary features. For manufacturers who support the auto industry by providing components and parts this presents both opportunities as well as challenges.
The very nature of what defines a car is being challenged by a rise in demand for alternative energy and hybrid electric vehicles (HEV). These are, in general, placing an increasing burden upon the underlying design of the electronic structure and makeup of vehicles. Specifically this necessitates an increase in the number of Power MOSFETs (metal oxide semiconductor field-effect transistors) which are required to deliver everything from climate control and power steering to infotainment and hybrid motor drivetrains.
Contrasting these growing requirements for ever improved power management is an industry wide shift towards lighter vehicles which can offer the consumer greater efficiency and cost savings derived from better fuel economy. The result is a desire for a vehicle which offers greater and more advanced technology, yet which manages to accommodate this capability in increasingly compact settings.
The pressing need therefore is to deliver to industry MOSFETs in more compact and efficient packaging which can handle the increased power requirements and remove weight and free up space within the vehicle’s electrical system. However weight and space saving are not the only considerations which are relevant to these growing set of automotive applications.
A knock on effect of the growth in the complexity of automotive electrical systems is a corresponding increase in heat generation and conductive losses which these can create. When combined with a movement towards smaller and more compact packaging for MOSFETs, there is likely to be less opportunity to extract excess heat and a further increase of the internal temperature of the devices.
As such, next generation MOSFETs need to be able to offer methods to overcome heat dissipation and managed power losses which can be caused by overheating. Finally the nature of automotive applications necessitates components which are sufficiently durable to withstand the movement and temperature changes which cars go through in motion.
Heat dissipation is another key issue to address, as the size of power MOSFET packages decreases, the internal temperature of these device increases exponentially due to difficulty in extracting excess heat. At higher currents, the on-resistance can increase further and more heat is generated. Heat impacts functionality, safetyClass X capacitors are used in “across-the-line” applications where their failure would not lead to electric shock. Class X safety caps are used between the “live” wires carrying the incoming AC current. In this position, a capacitor failure should not cause any electrical shock hazards, rather, a capacitor failure “between-the-lines” would usually cause a fuse or circuit breaker to open. as well as reliability. ON Semiconductor developed the leading ATPAK package technology to increase possible heat dissipation.