We have done some investigation in using COTS components for low orbit space usage. As a part of this we have done some TID radiation testing of one of our standard designs.
The TID (Total Ionizing Dose Radiation Testing) is performed using gamma rays provided by a JLS 81-22 Cobalt-60 source.
The design includes 3x TPS7A8801RTJT LDO’s. All of them failed at more or less the same time, and they were the only components failing. The failed around a total dose of 12krad.
We know that these LDO are COTS and not space rated (TPS7A8801RTJT).
But is it possible to get some feedback from TI in relation to what the suspected/expected failure mechanism would be, if these LDO’s were exposed to radiation.
- For instance, would it be a short between input and output for at short while and then the internal connection between those would burn leaving the output high impedance?
- Just degradation of silicon, with random failures?
- Main MOSFET fails?
- TBD?
We are kind of curious since they have an unusual failing pattern.
Each LDO contains 2 outputs. The 3 LDO’s are placed different places on the board and connected to different sources and loads. Still all 6 outputs failed more or less at the same radiation level.
More details about failure
- Output delivers close to 0V out even in LDO input enabled and LDO powered.
- There is a high impedance between the input and output of the LDO.
