Patent attributes
In an embodiment of the invention, a charge pump circuit has a latch-up prevention circuit. The latch-up prevention circuit has a depletion P-channel MOS transistor and a resistor serially connected with each other between a negative output terminal and a ground terminal. A first bidirectional PNP-transistor is connected between a back gate of the depletion MOS transistor and the ground terminal. A second bidirectional PNP-transistor is connected between the back gate of the depletion MOS transistor and the negative output terminal. A third bidirectional PNP-transistor is between the ends of the resistor to bypass it. The base of the first bidirectional PNP-transistor is connected to the negative output terminal, the gate of the depletion MOS transistor and the bases of the second and third bidirectional PNP-transistors are connected to the ground terminal.
