Patent ID: 6703943
Filing Date: 2004-03-09
Classification: G08C

Abstract:
An assembly for signal transfer between a receiving station and a transmitting station as well as for power supply of said transmitting station in which these two stations are connected to each other via a two-wire line, via which an analog signal current variable between two limiting values is transmitted, this signal current representing a measured value sensed by a sensor in said transmitting station and forming the supply current needed to operate said transmitting station, said transmitting station comprisinga circuit generating a constant operating voltage for said transmitting station; and a controllable current source being included in said transmitting station which dictates the current flowing via said two-wire line as a function of said measured value and which is fed from a supply voltage source in said receiving station, said current source being a series current regulator fed from said supply voltage source in said receiving station, a charge pump being connected to the output of said current source, said charge pump generating from the voltage appearing at said output of said current source the operating voltage needed for operating said sensor and a signal processing circuit connected thereto, and a parallel regulator for maintaining the input voltage or respectively the output voltage of said charge pump constant being connected to the input and output respectively of said charge pump, wherein said current source is bridged by a voltage regulator furnishing in a starting phase an input voltage (Uv1) for said charge pump, said current source being configured so that it does not furnish an output current in the starting phase until said charge pump outputs an output voltage sufficient for its operation, said voltage regulator being configured so that it changes to the OFF state as soon as said output voltage (Uout) has attained said operating voltage.