Abstract: Aiming at the deficiencies of high cost and poor controllability of holding brake power supply under analog control chip, a kind of holding brake power supply system based on digital controller was designed. Using the STC32G microcontroller as the controller, the AC voltage is converted into DC voltage through a rectification and filtering circuit, and then the Buck converter was used for voltage reduction to supply power to the holding brake coil.STC32G built-in 12 bit high-precision analog-to-digital converter (ADC) module was used to sample voltage and current, and adjust voltage feedback in real-time.Based on sliding mode control theory, the approaching law function was improved, and a new type of non singular terminal sliding mode controller was designed to further improve the dynamic response and anti-interference performance of the holding brake power supply.Finally, a simulation model based on MATLAB/Simulink and an STC32G experimental platform was built to verify the effectiveness of the designed power supply.The results show that compared to the PI controller, the new non singular terminal sliding mode controller in the bandgap power supply system improves the voltage recovery time by more than 62.5% and 66.7% under the conditions of reference voltage change and load mutation, respectively. The designed bandgap power supply system has good dynamic and steady-state performance and anti-interference ability.