In general, the subject matter described in this disclosure can be embodied in a system that implements power supply protection. The system includes first circuitry, second circuitry, a first power supply that is configured to power the first circuitry, and a second power supply that is configured to power the first circuitry and the second circuitry. The system also includes a power supply sensor including an input that is connected to the first power supply, and an output. The system also includes a hysteresis buffer including an input that is connected to the output of the power supply sensor, and an output that is connected to the first circuitry in a configuration that transitions the first circuitry to a protected state as a result of the hysteresis buffer transitioning output states.