Voltage regulator provided with a current limiter

Abstract

A voltage regulator for converting an input voltage (Vi) into an output voltage (Vo). The input voltage may be burdened with a ripple. The output voltage (Vo) supplied by the voltage regulator is virtually free from ripple. The voltage regulator comprises an input terminal (1) for receiving the input voltage (Vi), an output terminal for supplying the output voltage (Vo) in response to the input voltage (Vi), and current limiting means for limiting the maximum absolute value of an output current (Io) taken from the output terminal (2). The current limiting means comprise a field effect transistor (TCL). The voltage regulator further comprises a first current mirror (CM1) comprising transistors (T11, T12), a second current mirror (CM2) comprising transistors (T13, T14), and a third current mirror comprising transistors (T15, T16). In a typical operation, the field effect transistor (TCL) is in the linear region and thus behaves like a resistance. With an increasing output current (Io), the current through the field effect transistor (TCL) also increases, and the voltage between the drain and the source of the field effect transistor (TCL) increases. When the voltage between the drain and the source of the field effect transistor (TCL) has exceeded a certain level, the field effect transistor (TCL) enters its saturation region and accordingly behaves like a constant-current source. As a consequence the output current (Io) can no longer rise.

Dependencies are inferred from the claim text.