A control apparatus for an electro-optic element comprises a first voltage converter in connection with a power supply. The first voltage converter is configured to receive a supply voltage from the power supply and output a first voltage. A first storage capacitor is in connection with the first voltage converter and configured to store first energy at the first voltage. A second storage capacitor is configured to store second energy at a second voltage, wherein the second energy is supplied by the power supply. A driving circuit in conductive connection with the second storage capacitor and configured to supply a driving voltage to the electro-optic element. In response to a failure of the power supply, the first storage capacitor is configured to supply the first energy to a controller and the second storage capacitor is configured to supply the second energy to the driving circuit.