Abstract: Through the different LET heavy ion irradiation test of domestic bipolar process step-down switching regulator used in satellites, the output voltage and current of the device measured during the experiment, we quantitatively evaluate the radiation resistance performance of the step-down switching regulator. The experimental results show that the single event upset threshold of this device is lower than 5 MeV·cm 2·mg -1 . When the LET value of the irradiated heavy ion increases to 37.37 MeV·cm 2·mg -1 , the single event latch-up occurs in the device, and the power supply current increases sharply from 6 mA to 24 mA. Based on the analysis of heavy ion radiation data, the position and structure characteristics of the sensitive region of single event effect in the device are obtained by means of the pulsed laser. The analysis shows that the parasitic PNP transistor is formed between the devices in the same isolation island and the PNPN thyristor structure is formed between the parasitic PNP and the NPN transistor in the isolation island due to the existence of multiple functional modules sharing a single isolation island inside the chip. When the LET value of the incident heavy ion is large enough, the parasitic PNPN structure will be turned on and latched. The simulation software Spectre is used to simulate the transient fault injection at electric parameter level, and the phenomenon of single event latch-up effect under bipolar structure is reproduced.

Key words: Bipolar process, Heavy ion irradiation, Single event latch-up effect, Damage mechanism