Techniques for implementing a fault-tolerant power supply are described. In an example, a system converts an alternating-current (AC) voltage to an initial direct current (DC) voltage. The system further converts the initial DC voltage to a first DC voltage and a second DC voltage. The system applies the first DC voltage to a high-priority device such as a metrology device. The system applies the second DC voltage to a low-priority or peripheral device. When the initial DC voltage is outside a voltage range, the system deactivates the second DC voltage to the lower-priority device and maintains the first DC voltage to the metrology device.