US5239440A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic discharge protection for integrated circuits
Assignee: National Semiconductor Corp
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Filing: 1992-08-14
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Granted: 1993-08-24
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Expires: 2012-08-14
Abstract
Abstract A circuit is disclosed for protecting an integrated circuit or another circuit from damage due to electrostatic discharge. The protection circuit includes a triggering circuit and a clamping circuit. In response to an electrostatic discharge, the triggering circuit turns on the clamping circuit to clamp a node of the protected circuit to both an upper and a lower potential. This allows the electrostatic discharge to dissipate harmlessly to either potential source, depending upon its polarity. Preferably, the triggering circuit consists of a resistor-capacitor network which generates the required control signal every time power is supplied to the circuit being protected, while the clamping circuit consists of a pair of transistors for connecting an input pin to both the high and low potential sources. Typically, one protection circuit is coupled to each input/output pin of the integrated circuit being protected.
Inventors
- 👤 Richard B. Merrill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:12
CPC Classifications
H; H10; H10D; H10D89/00; H10D89/60; H10D89/601
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
114 words
A protection circuit for protecting a functional circuit from electrostatic discharge, the functional circuit having a power supply with a first potential, a low potential source with a potential lower than the first potential, and an input node connected between the power supply and the low potential source, the protection circuit comprising: a first node connected between the power supply and the input node; a second node connected between the low potential source and the input node; triggering means for generating a control signal in response to an electrostatic discharge; and switch means connected to the triggering means for switchably connecting the first node to the second node in response to the control signal.
Claim 2
Dependent Claim
114 words
A protection circuit for protecting a functional circuit from electrostatic discharge, the functional circuit having a power supply with a first potential, a low potential source with a potential lower than the first potential, and an input node connected between the power supply and the low potential source, the protection circuit comprising: a first node connected between the power supply and the input node; a second node connected between the low potential source and the input node; triggering means for generating a control signal in response to an electrostatic discharge; and switch means connected to the triggering means for switchably connecting the first node to the second node in response to the control signal.
Claim 3
Dependent Claim
41 words
A protection circuit as in claim 1 wherein the switch means comprises: a first transistor connected between the input node of the functional circuit and the first node, and a second transistor connected between the input node and the second node.
Claim 4
Dependent Claim
36 words
A protection circuit as in claim 2 wherein each of the first and second transistors is connected to receive the control signal and in response connected to input node to the corresponding first and second nodes.
Claim 5
Dependent Claim
20 words
A protection circuit as in claim 3 wherein each of the first and second transistors comprises a field effect transistor.
Claim 6
Dependent Claim
26 words
A protection circuit as in claim 1 wherein the triggering means comprises a resistor-capacitor network for triggering the switch means whenever an electrostatic discharge event occurs.
Claim 7
Dependent Claim
26 words
A protection circuit as in claim 5 wherein the resistor-capacitor network comprises a serially connected resistor and capacitor between the first node and the second node.
Claim 8
Dependent Claim
26 words
A protection circuit as in claim 6 wherein the resistor-capacitor network is chosen to have a time constant greater than the duration of the electrostatic discharge.
Claim 9
Dependent Claim
24 words
A protection circuit as in claim 1 wherein the switch means comprises a single transistor connected to the first node and the second node.
Claim 10
Dependent Claim
25 words
A protection circuit as in claim 8 wherein the single transistor comprises a field effect transistor having a control electrode connected to the trigger circuit.
Claim 11
Dependent Claim
43 words
A protection circuit as in claim 1 wherein the triggering circuit comprises: a transistor connected between the first node and the second node, whereby an electrostatic discharge on the first node will turn on the transistor to connect the first node to ground.
Claim 12
Dependent Claim
131 words
An integrated circuit protected from electrostatic discharge comprising: a functional circuit having a plurality of connection nodes for performing operations in response to signals supplied to the connection nodes, the functional circuit having a power supply with a first potential, a low potential source with a potential lower than the first potential, and at least a first connection node connected to the power supply and a second connection node connected to the low potential source; a plurality of switch means, one connected to each of the corresponding ones of the plurality of connection nodes, each switch means for connecting that connection node to both the first and second connection nodes in response to a control signal; and a triggering circuit for generating the control signal in response to an electrostatic discharge.
Claim 13
Dependent Claim
131 words
An integrated circuit protected from electrostatic discharge comprising: a functional circuit having a plurality of connection nodes for performing operations in response to signals supplied to the connection nodes, the functional circuit having a power supply with a first potential, a low potential source with a potential lower than the first potential, and at least a first connection node connected to the power supply and a second connection node connected to the low potential source; a plurality of switch means, one connected to each of the corresponding ones of the plurality of connection nodes, each switch means for connecting that connection node to both the first and second connection nodes in response to a control signal; and a triggering circuit for generating the control signal in response to an electrostatic discharge.
Claim 14
Dependent Claim
32 words
A protection circuit as in claim 11 wherein the triggering circuit also generates the control signal for a short time each time power is applied to the functional circuit is powered up.
Claim 15
Dependent Claim
21 words
An integrated circuit as in claim 12 wherein the triggering circuit is also connected between the first and second connection node.
References Cited (Backward Citations)
US4870530A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-23 | 1997-02-22 | 1997-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-23 | 2001-02-22 | 2001-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-23 | 2005-02-22 | 2005-08-24 | $7700.00 | Window Closed / Lapsed |