Patent US5818669A successfully refreshed from Google Patents.
US5818669A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zener diode power dissipation limiting circuit
Assignee: Fairchild Semiconductor Corp
•
Filing: 1996-07-30
•
Granted: 1998-10-06
•
Expires: 2016-07-30
Abstract
Abstract A circuit that utilizes a Zener diode to protect elements of a circuit from an over-voltage condition. When a fault occurs, causing an over-voltage condition, the voltage applied to the elements of the circuit is limited by the Zener diode. In addition, the circuit senses the over-voltage condition. Upon sensing the over-voltage condition, the circuit gradually reduces the power applied to that portion of the circuit to a minimum level. If the over-voltage condition persists for a predetermined amount of time, power is shut down to that portion of the circuit until the circuit is re-started. Because the amount of time that an over-voltage condition may occur is limited, the Zener diode may have a lower power rating than would otherwise be required. This is because the power dissipation capabilities of a Zener diode conducting current under a reverse bias are greater when the reverse bias is of a short duration than when the reverse bias is of a long duration. For example, the inventor has identified a Zener diode that is represented to have an ability to withstand 500 milli-watts under steady state conditions, but that can withstand for a limited duration a peak surge of many times the steady state power rating. In the preferred embodiment, the circuit limits voltage in a resonant circuit utilizing two Zener diodes coupled in series.
Inventors
- 👤 Urs H. Mader
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:58
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; H02M7/538; H05; H05B; H05B41/00; H05B41/14; H05B41/26; H05B41/28; H05B41/282; H05B41/285; H05B41/2851; H05B41/2855; H02M1/00; H02M1/32; Y; Y02; Y02B; Y02B70/00; Y02B70/10
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
140 words
A circuit for protecting against an overvoltage condition, comprising: a. a resonant circuit; b. a load coupled to the resonant circuit; c. a first Zener diode coupled to a node of the resonant circuit for limiting a voltage at the node when the first Zener diode breaks down; and d. means for controlling power delivery to the resonant circuit, the means for controlling including means for reducing power delivery to the circuit to a predetermined power level when the voltage at the node exceeds a predetermined voltage level wherein the predetermined power level results in a voltage level at the node that causes the first Zener diode to continue to break down and further including means for stopping power delivery to the resonant circuit a predetermined amount of time after the voltage at the node exceeds the predetermined voltage level.
Claim 2
Dependent Claim
140 words
A circuit for protecting against an overvoltage condition, comprising: a. a resonant circuit; b. a load coupled to the resonant circuit; c. a first Zener diode coupled to a node of the resonant circuit for limiting a voltage at the node when the first Zener diode breaks down; and d. means for controlling power delivery to the resonant circuit, the means for controlling including means for reducing power delivery to the circuit to a predetermined power level when the voltage at the node exceeds a predetermined voltage level wherein the predetermined power level results in a voltage level at the node that causes the first Zener diode to continue to break down and further including means for stopping power delivery to the resonant circuit a predetermined amount of time after the voltage at the node exceeds the predetermined voltage level.
Claim 3
Dependent Claim
56 words
The circuit according to claim 1 wherein the predetermined amount of time is in the range of 50 ms to 2 s whereby a required power dissipation capability of the first Zener diode is reduced in comparison to a required power dissipation capability of the first Zener diode had the predetermined amount of time been infinite.
Claim 4
Dependent Claim
68 words
The circuit according to claim 1 further comprising a second Zener diode coupled in series with the first Zener diode wherein the predetermined amount of time is in the range of 50 ms to 2 s whereby a required power dissipation capability of the Zener diodes is reduced in comparison to a required power dissipation capability of the Zener diodes had the predetermined amount of time been infinite.
Claim 5
Dependent Claim
13 words
The circuit according to claim 1 wherein the load is a fluorescent lamp.
Claim 6
Dependent Claim
82 words
A circuit for protecting a circuit element against damage caused by an overvoltage condition at a node, comprising: a. means for delivering power to the circuit; b. means for reducing an amount of power delivery to the circuit to a predetermined power level after a voltage at the node exceeds a predetermined voltage level; and c. means for stopping delivery of power to the circuit when the voltage at the node exceeds the predetermined voltage level for a predetermined amount of time.
Claim 7
Dependent Claim
82 words
A circuit for protecting a circuit element against damage caused by an overvoltage condition at a node, comprising: a. means for delivering power to the circuit; b. means for reducing an amount of power delivery to the circuit to a predetermined power level after a voltage at the node exceeds a predetermined voltage level; and c. means for stopping delivery of power to the circuit when the voltage at the node exceeds the predetermined voltage level for a predetermined amount of time.
Claim 8
Dependent Claim
57 words
The circuit according to claim 5 further comprising a first Zener diode wherein a cathode of the first Zener diode is coupled to the node and further comprising a second Zener diode having an anode coupled to an anode of the first Zener diode and the second Zener diode having a cathode coupled to a ground node.
Claim 9
Dependent Claim
28 words
The circuit according to claim 5 wherein the circuit comprises a resonant circuit, wherein the resonant circuit is coupled to a load for drawing power from the circuit.
Claim 10
Dependent Claim
37 words
The circuit according to claim 5 wherein the means for reducing reduces the power delivery to the circuit to the predetermined power level within 1 ms after the voltage at the node exceeds the predetermined voltage level.
Claim 11
Dependent Claim
22 words
The circuit according to claim 5 wherein the predetermined amount of time is in the range of 50 ms to 2 s.
Claim 12
Dependent Claim
72 words
A circuit for protecting against an overvoltage condition, comprising: a. means for delivering power to the circuit; b. a Zener diode coupled to a node of the circuit; and c. means for reducing power delivery to the circuit to a predetermined power level when the Zener diode breaks down wherein the predetermined power level results in a voltage level at the node that causes the Zener diode to continue to break down.
Claim 13
Dependent Claim
72 words
A circuit for protecting against an overvoltage condition, comprising: a. means for delivering power to the circuit; b. a Zener diode coupled to a node of the circuit; and c. means for reducing power delivery to the circuit to a predetermined power level when the Zener diode breaks down wherein the predetermined power level results in a voltage level at the node that causes the Zener diode to continue to break down.
Claim 14
Dependent Claim
31 words
The circuit according to claim 10 further comprising means for stopping power delivery to the node after the Zener diode has continued to break down for a predetermined amount of time.
Claim 15
Dependent Claim
22 words
The circuit according to claim 11 wherein the predetermined amount of time is in the range of 50 ms to 2 s.
Claim 16
Dependent Claim
30 words
The circuit according to claim 11 wherein a circuit element requires the voltage at the node to exceed the breakdown voltage of the Zener diode in order to begin operation.
Claim 17
Dependent Claim
14 words
The circuit according to claim 13 wherein the circuit element is a fluorescent lamp.
Claim 18
Dependent Claim
18 words
The circuit according to claim 14 wherein the circuit comprises a resonant circuit coupled to the fluorescent lamp.
Claim 19
Dependent Claim
49 words
A circuit for protecting against an overvoltage condition, comprising: a. means for delivering power to the circuit; b. a Zener diode coupled to a node of the circuit; and c. means for stopping power delivered to the circuit a predetermined amount of time after the Zener diode breaks down.
Claim 20
Dependent Claim
49 words
A circuit for protecting against an overvoltage condition, comprising: a. means for delivering power to the circuit; b. a Zener diode coupled to a node of the circuit; and c. means for stopping power delivered to the circuit a predetermined amount of time after the Zener diode breaks down.
Claim 21
Dependent Claim
50 words
The circuit according to claim 16 further comprising means for reducing power delivered to the circuit to a predetermined power level when the Zener diode breaks down wherein the predetermined power level results in a voltage level at the node that causes the Zener diode to continue to break down.
Claim 22
Dependent Claim
22 words
The circuit according to claim 16 wherein the predetermined amount of time is in the range of 50 ms to 2 s.
Claim 23
Dependent Claim
30 words
The circuit according to claim 16 wherein a circuit element requires the voltage at the node to exceed the breakdown voltage of the Zener diode in order to begin operation.
Claim 24
Dependent Claim
14 words
The circuit according to claim 19 wherein the circuit element is a fluorescent lamp.
Claim 25
Dependent Claim
18 words
The circuit according to claim 20 wherein the circuit comprises a resonant circuit coupled to the fluorescent lamp.
Claim 26
Dependent Claim
287 words
A circuit for providing power to a fluorescent lamp and for preventing damage to a circuit element caused by an overvoltage condition at a circuit node, the circuit comprising: a. a power source; b. a resonant circuit coupled to the power source wherein the resonant circuit comprises the circuit node; c. a fluorescent lamp coupled to receive power from the resonant circuit wherein the fluorescent lamp requires a minimum voltage level for a minimum period of time to ignite; d. means for sensing a voltage representative of the voltage at the circuit node coupled to the circuit node; e. a controller circuit for controlling an amount of power delivered to the resonant circuit from the power source wherein the controller is unable to directly control a voltage at the circuit node and wherein the controller circuit comprises: i. means for reducing the amount of power delivered to the resonant circuit when the voltage at the circuit node exceeds a predetermined voltage level wherein the predetermined voltage level is higher than the minimum level required to cause the fluorescent lamp to ignite; ii. means for ceasing power delivery to the resonant circuit when the voltage at the circuit node exceeds the predetermined voltage level for a predetermined amount of time wherein the predetermined amount of time is longer than the minimum amount of time required for the fluorescent lamp to ignite; f. a first Zener diode having a first anode and a first cathode wherein the first cathode is coupled to the circuit node; and g. a second Zener diode having a second anode and a second cathode wherein the second anode is coupled to the first anode and the second cathode is coupled to the ground node.
Claim 27
Dependent Claim
287 words
A circuit for providing power to a fluorescent lamp and for preventing damage to a circuit element caused by an overvoltage condition at a circuit node, the circuit comprising: a. a power source; b. a resonant circuit coupled to the power source wherein the resonant circuit comprises the circuit node; c. a fluorescent lamp coupled to receive power from the resonant circuit wherein the fluorescent lamp requires a minimum voltage level for a minimum period of time to ignite; d. means for sensing a voltage representative of the voltage at the circuit node coupled to the circuit node; e. a controller circuit for controlling an amount of power delivered to the resonant circuit from the power source wherein the controller is unable to directly control a voltage at the circuit node and wherein the controller circuit comprises: i. means for reducing the amount of power delivered to the resonant circuit when the voltage at the circuit node exceeds a predetermined voltage level wherein the predetermined voltage level is higher than the minimum level required to cause the fluorescent lamp to ignite; ii. means for ceasing power delivery to the resonant circuit when the voltage at the circuit node exceeds the predetermined voltage level for a predetermined amount of time wherein the predetermined amount of time is longer than the minimum amount of time required for the fluorescent lamp to ignite; f. a first Zener diode having a first anode and a first cathode wherein the first cathode is coupled to the circuit node; and g. a second Zener diode having a second anode and a second cathode wherein the second anode is coupled to the first anode and the second cathode is coupled to the ground node.
Claim 28
Dependent Claim
55 words
The circuit according to claim 22 whereby the fluorescent lamp may be ignited when the fluorescent lamp is not defective and is present and whereby a circuit element is protected against an overvoltage condition when the fluorescent lamp is defective or absent by the Zener diodes having lower power ratings than would otherwise be required.
References Cited (Backward Citations)
US2483815A
Cited
US2967267A
Cited
US3840795A
Cited
US3292579A
Cited
US3549990A
Cited
US3828203A
Cited
US3611021A
Cited
US3671782A
Cited
US3953768A
Cited
US3723891A
Cited
US3772625A
Cited
US3758823A
Cited
US3778677A
Cited
US3893036A
Cited
US3921005A
Cited
US4031449A
Cited
US4063108A
Cited
US4145592A
Cited
US4030058A
Cited
US4038625A
Cited
US4146857A
Cited
US4318608A
Cited
US4144462A
Cited
US4127795A
Cited
US4277728A
Cited
US4172981A
Cited
US4277726A
Cited
US4225825A
Cited
US4207498A
Cited
US4210846A
Cited
US4260943A
Cited
US4251752A
Cited
US4303902A
Cited
US4297614A
Cited
US4723098A
Cited
US4390844A
Cited
EP0059064B1
Cited
DE3233655A1
Cited
US4414493A
Cited
US4412265A
Cited
US4441053A
Cited
US4700113A
Cited
US4441054A
Cited
US4453109A
Cited
US4523131A
Cited
US4495446A
Cited
US4498031A
Cited
US4585974A
Cited
US4698554A
Cited
US4486689A
Cited
US4496896A
Cited
US4528482A
Cited
US4543556A
Cited
US4572988A
Cited
DE3432266A1
Cited
US4612479A
Cited
US4604552A
Cited
EP0178852A1
Cited
US4654573A
Cited
US4763239A
Cited
US4686427A
Cited
US4717863A
Cited
US4893059A
Cited
US4806880A
Cited
US4704563A
Cited
US4800328A
Cited
US4739227A
Cited
US4874989A
Cited
US4896077A
Cited
WO1992001334A1
Cited
US4935669A
Cited
US4920299A
Cited
US4952849A
Cited
US5111118A
Cited
US4942352A
Cited
US5049790A
Cited
US5045732A
Cited
US4962344A
Cited
US5015919A
Cited
US5048033A
Cited
US5237242A
Cited
US5202608A
Cited
US5214352A
Cited
US5177408A
Cited
US5367224A
Cited
US5367242A
Cited
US5384516A
Cited
US5367223A
Cited
US5216402A
Cited
US5408162A
Cited
US5264776A
Cited
US5410188A
Cited
US5394020A
Cited
US5363020A
Cited
US5410221A
Cited
US5615093A
Cited
US5642066A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-10-05 | 2002-04-06 | 2002-10-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-10-05 | 2006-04-06 | 2006-10-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-10-05 | 2010-04-06 | 2010-10-06 | $7700.00 | Window Closed / Lapsed |