Low dose failures of hardened DC-DC power converters

Radiation tests of Interpoint DC-DC converters, guaranteed by the manufacturer to 100 krad(Si), showed catastrophic failures at total dose levels as low as 4 krad(Si). Special diagnostic tests showed that failures were caused by an internal CMOS MOSFET driver chip being used in an application that differed from earlier radiation tests of the component. This paper discusses radiation testing, failure modes, and the method used to overcome this problem weeks prior to launch of two space systems.