[Background] Magnetoresistive random access memory (MRAM) has the advantages of non-volatility

fast speed

low power consumption

high endurance

and long data retention

which make it a potential candidate forapplication in aerospace electronic systems. [Purpose] This study aims to examine the total ionization dose(TID) and transient dose rate (TDR) effects of a Toggle MRAM. [Methods] A remote on-line test system was designed for in-situ measurement of the radiation effect of the MRAM. The TID and TDR response of MRAM were studied experimentally in various working modes. [Results]The following results are obtained: 1) During TID experiment

the early response of the MRAMs is an increase of the supply current. Bit errors occur at a total dose of 30 krad(Si). 2) During the TDR experiment

neither data nor function errors was observed in static power-on mode and dynamic read mode

whereas data write failure occurred in dynamic write mode. Reason for the write failure may bethat the global photocurrent of the circuit caused a fluctuation in the power supply

which triggered the write protection of the device and hindered the following data writing process. [Conclusions] Results from the experiments indicate that MRAM exhibits malfunctions under total dose and transient ionizing radiation environments. The radiation sensitive and vulnerable part of the MRAM is its peripheral circuits.