Patent ID: 7453312

Claim:
A voltage regulator coupled to a first voltage source and a second voltage source, the voltage regulator comprising: a first pump circuit coupled to the first voltage source; a second pump circuit coupled to the second voltage source; and a control circuit comprising: a first resistor having a first end coupled to an output terminal of the first pump circuit; a second resistor having a first end coupled to a second end of the first resistor and a second end coupled to an output terminal of the second pump; a first transistor having a first terminal coupled to the output terminal of the first pump circuit and a second end coupled to the second end of the first resistor; a second transistor having a first end coupled to a third terminal of the first transistor, a second end and a third end both coupled to the second voltage source; a first voltage comparison circuit having a first input terminal coupled to a reference voltage and a second input terminal coupled to the third terminal of the first transistor; a first voltage divider coupled to the output terminal of the first pump circuit and the output terminal of the second pump; a second voltage divider coupled to the first voltage source and the second voltage source; and a second voltage comparison circuit having a first input terminal coupled to the output terminal of the first voltage divider, a second input terminal coupled to the output terminal of the second voltage divider, and a third input terminal coupled to an output terminal of the first voltage comparison circuit, the second voltage comparison circuit being used for controlling operations of the first pump circuit and the second pump circuit according to the voltage levels of the three input terminals of the second voltage comparison circuit.