Enhanced low-dose-rate sensitivity of a low-dropout voltage regulator

Ionization-induced degradation of the 29372 low-dropout voltage regulator is most severe at low-dose-rate (/spl sim/10 mrad(SiO/sub 2/)/s) and zero load current. The most sensitive parameter is the maximum output drive current, which is a function of the gain of the large lateral pnp output transistor. Significant degradation of this parameter occurs at 5-10 krad(SiO/sub 2/) at low-dose-rate. A moderate load current (/spl sim/250 mA) during irradiation significantly mitigates the damage. The mitigation of the damage is proportional to irradiation load current and is not a strong function of irradiation temperature or input voltage. The mechanism for the mitigation of damage appears to be current density dependent passivation of interface and/or border traps by mobile hydrogen-related species. The worst-case space system application is in unbiased spares.