Constant-voltage power circuit with fold back current limiting capability

#This application claims priority to Japanese Patent Application No. 2005-132446, filed with the Japanese Patent Office on Apr. 28, 2005, the entire contents of which are hereby incorporated by reference.

#The invention generally relates to constant-voltage power circuits, and more specifically to a constant-voltage power circuit incorporating an over-current protection circuit having a fold back current limiting capability operative through low input voltages.

#In order to implement overcurrent protection for constant-voltage power supply circuits employing series regulators, overcurrent protection circuits have been widely used such as, for example, a current limiting circuit configured to prevent a current output from exceeding a predetermined current, and an overcurrent protection circuit configured to limit a current output under short circuit conditions.

#In the following drawings, like reference numerals will be used to refer to like elements, in which:

#FIG. 1 is a diagrammatic circuit diagram illustrating a constant-voltage power supply circuit according to an exemplary embodiment of the invention;

#FIG. 2 is a diagrammatic circuit diagram illustrating a constant-voltage power supply circuit according to another exemplary embodiment of the invention;

#In the detailed description which follows, specific embodiments are described on a constant-voltage power circuit incorporating an over-current protection circuit having a fold back current limiting capability.

#It is understood, however, that the present disclosure is not limited to these embodiments. For example, it is appreciated that the present power circuit and its structure may also be adaptable to various circuits. Other embodiments will be apparent to those skilled in the art upon reading the following description.

#In addition, in the description that follows specific terminology is used in many instances for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner.