Patent ID: 7119459
Filing Date: 2006-10-10
Classification: H02J,H02M

Abstract:
1. A switching circuit for controlling the supply of power from an exhaustible power source to a load which includes a control circuit, a power switch which is controlled by the control circuit in response to signals from a man-machine-interface (MMI) and said power switch, when closed, connects the power source to the load, the MMI comprising at least a switch connected to at least one signal switch input of the control circuit, the switch does not form a serial element in a circuit that transfers power from the power supply to the load and wherein the control circuit further provides at least one function selected from the following functions: (a) a power source level indication which is determined by comparing a fixed reference voltage to a closed circuit supply voltage and which is displayed to a user, even at times when the load has not been activated through the MMI; and (b) a function wherein the control circuit compares the voltage of the power source to a fixed reference voltage and, in response to the comparison, controls a duty cycle of the power switch to provide a substantially constant supply of power from the power source to the load over a voltage range of the power source.