US4922133A
Expired / Lapsed
US
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Voltage detecting circuit
Assignee: Toshiba Corp
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Filing: 1988-07-29
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Granted: 1990-05-01
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Expires: 2008-07-29
Abstract
Abstract A voltage detecting circuit comprising a voltage-input terminal for receiving a first voltage or a second voltage higher than the first voltage, switch means connected between the voltage-input terminal and a first node, and an inverter circuit having an input terminal coupled to the first node and an output terminal coupled to a second node. The switch circuit is turned on when the voltage at the voltage-input terminal is higher than a predetermined value which is between the higher than the first voltage and lower than the second voltage, and is turned off when the voltage at the voltage-input terminal is lower than the predetermined value. The inverter circuit includes a first transistor having a source-drain path coupled between a first power-source potential terminal and the second node, a current control section for maintaining a current flowing through the source-drain path of the first transistor at a predetermined value, and a second transistor having a source-drain path connected between the second node and a second power-source potential terminal and a gate coupled to the first node.
Inventors
- 👤 Hiroshi Iwahashi
- 👤 Hiroto Nakai
- 👤 Masamichi Asano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:43
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/30; H03K17/302; H03K5/00; H03K5/01; H03K5/08
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
227 words
A voltage detecting circuit which comprises: a voltage-input terminal; first and second nodes; switch means connected between the voltage-input terminal and the first node, the switch means being turned on when a potential at the voltage-input terminal is higher than a predetermined value which is between a first voltage and a second voltage which is higher than the first voltage, and being turned off when the potential at the voltage-input terminal is lower than the predetermined value; a first power-source potential terminal; a second power-source potential terminal; an inverter circuit having an input terminal connected to the first node and an output terminal connected to the second node, and including a first transistor having a source-drain path connected between the first power-source potential terminal and the second node, and a second transistor having a source-drain path connected between the second node and the second power-source potential terminal and a gate connected to the first node; and current control means for causing the current flowing through the source-drain path of the first transistor to be substantially controlled, whereby to maintain the threshold voltage of the inverter circuit substantially constant irrespective of a potential at the first power-source potential terminal, said current control means including a current-source, the current control means and the first transistor being connected in series between the first power-source potential terminal and the second node.
Claim 2
Dependent Claim
227 words
A voltage detecting circuit which comprises: a voltage-input terminal; first and second nodes; switch means connected between the voltage-input terminal and the first node, the switch means being turned on when a potential at the voltage-input terminal is higher than a predetermined value which is between a first voltage and a second voltage which is higher than the first voltage, and being turned off when the potential at the voltage-input terminal is lower than the predetermined value; a first power-source potential terminal; a second power-source potential terminal; an inverter circuit having an input terminal connected to the first node and an output terminal connected to the second node, and including a first transistor having a source-drain path connected between the first power-source potential terminal and the second node, and a second transistor having a source-drain path connected between the second node and the second power-source potential terminal and a gate connected to the first node; and current control means for causing the current flowing through the source-drain path of the first transistor to be substantially controlled, whereby to maintain the threshold voltage of the inverter circuit substantially constant irrespective of a potential at the first power-source potential terminal, said current control means including a current-source, the current control means and the first transistor being connected in series between the first power-source potential terminal and the second node.
Claim 3
Dependent Claim
24 words
The voltage detecting circuit according to claim 1, further comprising a load circuit connected between said first node and said second power-source potential terminal.
Claim 4
Dependent Claim
85 words
The voltage detecting circuit according to claim 1, wherein said current control means includes a third transistor which is a depletion-type having a source-drain path, a gate, and a source; a source-drain path of said third transistor and the source-drain path of said first transistor are connected in series between said first power-source potential terminal and said second node; the gate and source of said third transistor are coupled to each other; and a gate of said first transistor is coupled to said first node.
Claim 5
Dependent Claim
28 words
The voltage detecting circuit according to claim 1, wherein said switch means includes an enhancement-type transistor having a gate and a drain which are connected to each other.
Claim 6
Dependent Claim
49 words
The voltage detecting circuit according to claim 1, wherein said switch means includes a fourth transistor which is an enhancement-type transistor of a first conductivity type having a source-drain path connected between said voltage-input terminal and said first node, and a gate connected to said first power-source potential terminal.
Claim 7
Dependent Claim
65 words
The voltage detecting circuit according to claim 5, wherein said switch means further includes a fifth transistor which is an enhancement-type transistor having a gate and a drain which are connected to each other, and a source-drain path, the source-drain path of said fourth transistor and the source-drain path of said fifth transistor are connected in series between said voltage-input terminal and said first node.
Claim 8
Dependent Claim
230 words
A voltage detecting circuit which comprises: a voltage-input terminal; first and second nodes; switch means connected between the voltage-input terminal and the first node, the switch means being turned on when a potential at the voltage-input terminal is higher than a predetermined value which is between a first voltage and a second voltage which is higher than the first voltage, and being turned off when the potential at the voltage-input terminal is lower than the predetermined value; a first power-source potential terminal; a second power-source potential terminal; a first transistor having a source connected to the first power-source potential terminal, a drain connected to the second node, and a gate; a second transistor having a drain connected to the second node, a source connected to the second power-source potential terminal, and a gate connected to the first node; and a current control circuit having an output terminal connected to the gate of the first transistor, for causing the current flowing through the source-drain path of said first transistor to be substantially controlled irrespective of a potential at the first power-source potential terminal, the current control circuit including level-shifting means connected between the first power-source potential terminal and the output terminal of the current control circuit, for setting the potential at the output terminal at a value less than a potential at said first power-source potential terminal by a predetermined value.
Claim 9
Dependent Claim
230 words
A voltage detecting circuit which comprises: a voltage-input terminal; first and second nodes; switch means connected between the voltage-input terminal and the first node, the switch means being turned on when a potential at the voltage-input terminal is higher than a predetermined value which is between a first voltage and a second voltage which is higher than the first voltage, and being turned off when the potential at the voltage-input terminal is lower than the predetermined value; a first power-source potential terminal; a second power-source potential terminal; a first transistor having a source connected to the first power-source potential terminal, a drain connected to the second node, and a gate; a second transistor having a drain connected to the second node, a source connected to the second power-source potential terminal, and a gate connected to the first node; and a current control circuit having an output terminal connected to the gate of the first transistor, for causing the current flowing through the source-drain path of said first transistor to be substantially controlled irrespective of a potential at the first power-source potential terminal, the current control circuit including level-shifting means connected between the first power-source potential terminal and the output terminal of the current control circuit, for setting the potential at the output terminal at a value less than a potential at said first power-source potential terminal by a predetermined value.
Claim 10
Dependent Claim
29 words
The voltage detecting circuit according to claim 7, wherein said level shifting means includes an enhancement-type transistor having a gate and a drain which are coupled to each other.
Claim 11
Dependent Claim
61 words
The voltage detecting circuit according to claim 7, which is formed on a chip on which an EPROM is formed, and wherein said first voltage is externally applied to said voltage-input terminal when the EPROM is set in a data-reading mode, and said second voltage is externally applied to said voltage-input terminal when the EPROM is set in a programming mode.
Claim 12
Dependent Claim
53 words
The voltage detecting circuit according to claim 9, wherein a power-source potential voltage is externally applied to said first power-source potential terminal when the EPROM is set in the data-reading mode, and a different power-source voltage is externally applied to said first power-source terminal when the EPROM is set in the programming mode.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-30 | 1993-10-30 | 1994-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-30 | 1997-10-30 | 1998-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-30 | 2001-10-30 | 2002-05-01 | $7700.00 | Window Closed / Lapsed |