REVERSE-CURRENT-PREVENTION CIRCUIT AND POWER SUPPLY CIRCUIT
First Claim
1. A reverse-current-prevention circuit comprising:
- a reverse-current-prevention transistor being a P-channel MOS transistor inserted in series between an input terminal supplied with a power supply voltage and an output stage transistor being a P-channel MOS transistor suppling a prescribed output voltage from an output terminal; and
a reverse-current-prevention controller configured to bring the reverse-current-prevention transistor from an on state to an off state according to exceedance of the output voltage to the power supply voltage, and having;
a first transistor being a depletion type P-channel MOS transistor and having a source connected to the output terminal and a gate connected to the input terminal, anda second transistor being a depletion type P-channel MOS transistor and having a source connected to a gate of the second transistor, a drain of the first transistor, and a gate of the reverse-current-prevention transistor, and a drain being grounded,wherein the reverse-current-prevention controller controls on and off of the reverse-current-prevention transistor according to a voltage of the drain of the first transistor.
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Accused Products
Abstract
A reverse-current-prevention circuit includes a reverse-current-prevention transistor of a P-channel MOS transistor inserted between an input terminal supplied with a power supply voltage and an output stage transistor of a P-channel MOS transistor providing an output voltage from an output terminal, and a reverse-current-prevention controller configured to turn the reverse-current-prevention transistor from on to off according to exceedance of the output voltage to the power supply voltage. The reverse-current-prevention controller includes a first transistor of a depletion type P-channel MOS transistor having a source and gate respectively connected to the output terminal and the input terminal, and a second transistor of a depletion type P-channel MOS transistor having a source and gate respectively connected to a drain of the first transistor and a gate of the reverse-current-prevention transistor, and a drain grounded.
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Citations
14 Claims
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1. A reverse-current-prevention circuit comprising:
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a reverse-current-prevention transistor being a P-channel MOS transistor inserted in series between an input terminal supplied with a power supply voltage and an output stage transistor being a P-channel MOS transistor suppling a prescribed output voltage from an output terminal; and a reverse-current-prevention controller configured to bring the reverse-current-prevention transistor from an on state to an off state according to exceedance of the output voltage to the power supply voltage, and having; a first transistor being a depletion type P-channel MOS transistor and having a source connected to the output terminal and a gate connected to the input terminal, and a second transistor being a depletion type P-channel MOS transistor and having a source connected to a gate of the second transistor, a drain of the first transistor, and a gate of the reverse-current-prevention transistor, and a drain being grounded, wherein the reverse-current-prevention controller controls on and off of the reverse-current-prevention transistor according to a voltage of the drain of the first transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A power supply circuit comprising:
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an output stage transistor being a P-channel MOS transistor and having a source supplied with a power supply voltage from an input terminal and a drain from which a prescribed output voltage is provided to an output terminal in accordance with a gate voltage applied to a gate of the output stage transistor; a reverse-current-prevention transistor being a P-channel MOS transistor and having a source connected to the input terminal and a drain connected to the source of the output stage transistor, and configured to prevent a reverse current coming from the output terminal through a parasitic diode on the source side of the output stage transistor; and a reverse-current-prevention controller configured to bring the reverse-current-prevention transistor from an on state to an off state according to exceedance of the output voltage to the power supply voltage, and having; a first transistor being a depletion type P-channel MOS transistor and having a source connected to the output terminal and a gate connected to the input terminal, and a second transistor being a depletion type P-channel MOS transistor and having a source connected to a gate of the second transistor, a drain of the first transistor, and a gate of the reverse-current-prevention transistor, and a drain being grounded.
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Specification