Patent ID: 6377681
Filing Date: 2002-04-23
Classification: H04M,Y02D

Abstract:
An apparatus including a signal line driving circuit with power control for selectively reducing internal power dissipation when driving an external load, comprising:a signal driver circuit that connects and provides an output signal to an external impedance, receives a source current and receives an input signal which corresponds to said output signal and in response thereto provides said output signal and a control signal which varies in relation to said output signal, wherein said output signal includes an output current which is approximately constant and an output voltage which varies in relation to said external impedance and said output current; and a power control circuit, coupled to said signal driver circuit, that connects to a plurality of voltage sources and receives therefrom a plurality of source voltages and receives said control signal and in response thereto conveys a selected one of said plurality of source voltages and said source current from one of said plurality of voltage sources to said signal driver circuit, wherein, a voltage difference between said selected one of said plurality of source voltages and said output voltage varies in relation to said control signal.