A Characterization Method for TID Versus Temperature Effects on Microelectronic Circuits

Over the past years, the space industry has witnessed a steady increase in the amount of commercial off-the-shelf (COTS) components deployed in spacecrafts. The use of COTS components, however, requires an increased effort from quality control professionals, and specifically from radiation hardness assurance (RHA) engineers. In fact, besides being less traceable, they can also occasionally introduce unusual failure modes, caused by the association of radiation effects paired with other environmental factors, such as temperature. Moreover, the absence of Radiation Hardening By Design makes these failure modes sometimes difficult to predict and characterize. This work investigates the combined effects of total ionizing dose (TID) and temperature variations on an LT1521 low dropout (LDO) voltage regulator. Particular attention was paid to lot characterization, and general conclusions were drawn on the TID versus temperature characterization method. The LT1521 was found to be liable to a complete shutdown for TID levels higher than 20 krad(Si) and at cold enough temperatures. Finally, the likely root causes of this failure mode were identified in the circuit.