Patent ID: 7667724

Claim:
A customer replaceable unit installable in a printing apparatus, the customer replaceable unit comprising: a component requiring high voltage electric power for operation; a low voltage power input; a high voltage power supply unit that cooperates with the low voltage power input in order to transform low voltage electric power from the low voltage power input into high voltage electric power for use by the component, the high voltage power supply unit including a controller; and a low voltage signal input, separate from the low voltage power input, wherein the high voltage power supply unit controls output of the high voltage electric power in response to signals received at the low voltage signal input, the signals received at the low voltage signal input comprise a set of interface commands independent of a type of the component and independent of a type of the high voltage power supply unit, the signals received at the low voltage signal input indicate a desired output of the high voltage power supply unit, and the controller determines a power level for operating the component in accordance with the desired output.