In order to find the responses of digital-to-analog (D/A) converters in ionizing radiation environment, total dose effect and room-temperature annealing behavior of a 10-bit bipolar D/A converter irradiated by different 60Co γ dose rates were investigated. The D/A converter is quite sensitive to dose rates, and its functions are normal at high dose rate irradiation. While under low-dose-rate case, it works out of the way and many parameters go beyond its permitted range. Thus, it exhibits an enhanced low-dose-rate sensitivity effect. Finally, possible mechanism was discussed based on the space charge model.