Anthony F. J. Murray, Tim McDonald, Harold Davis 1 , Joe Cao 1 , Kyle Spring 1 International Rectifier, 233 Kansas Street, El Segundo, CA 90245. USA ABSTRACT An extremely rugged technology has been developed for ultra low R DS(on) applications. This paper describes a methodology of guaranteeing repetitive avalanche performance as long as maximum operating junction temperature, T J(Max) , is not exceeded. The low R DS(on) . A product and the inherent ruggedness of the technology, qualified to the Q101 quality standard, make it particularly suitable for automotive 42V bus applications. This paper specifically looks at the 42V integrated starter-alternator design and the impact of it’s architecture on the performance of 75V power MOSFETs. 1. INTRODUCTION The increase in power requirements in today’s automobiles has forced auto manufacturers to consider higher supply voltages. The general trend is to move from the 14V bus towards a combined 42/14V bus. It is thought that high power loads (Electric Power Steering (EPS), Integrated Starter- Alternator (ISA) and Anti-lock Brakes (ABS), etc.) will run from the 42V bus, while some of the lower voltage systems (windshield wipers, power windows, etc.) will still run from the regular 14V rail. These new developments will place increased ruggedness requirements on today’s power MOSFETs. In tandem with the improvements in automobile design, power semiconductors have also been improved, trending towards lower R DS(on) and improved power handling. These technology advances have resulted in power semiconductor manufacturers making smaller die sizes for a given R DS(on) , giving rise to lower cost and reduced size and weight, but also the undesirable effects of increased power densities and thermal resistances. Hence today’s devices have achieved improved performance, but need to be even more rugged than before, and are sometimes required to withstand repetitive high voltage transients generated by di/dt and parasitic inductance. In fact, in the case of the integrated starter-alternator (ISA), 75V devices may even experience repetitive avalanche conditions during normal operation. 1 International Rectifier, HexFET America Facility, 41915 Business Park Drive. Temecula. CA 92590. USA. Extremely Rugged MOSFET Technology with Ultra-low R DS(on) Specified for A Broad Range of E AR Conditions