Power supply device for motor vehicle safety relevant systems attached to on board network

The energy supply device has a main energy supply (6) coupled to all safety-relevant braking system components (2,3,4,5) via switches (13,19,20,23,29,30) and at least one independent auxiliary energy supply (7,8), selectively connected to the system components via at least two supply nodes (14,24), switched between the main energy supply and the auxiliary energy supply.