In an arrangement for the power supply for a security domain of a device, a first battery is connected to a first input of a battery switchover device in the security region and a second battery is arranged in a non-security region of the device housing and is connected to a second input of the battery switchover device. The battery switchover device is coupled to a monitoring unit in the security region of the device. The monitoring unit is preferably composed of an analog-to-digital converter and a module processor for the evaluation of the connected battery voltages.