CN203289096U - Overvoltage protective circuit for composite piezoresistor - Google Patents
Overvoltage protective circuit for composite piezoresistor Download PDFInfo
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- CN203289096U CN203289096U CN2013203116585U CN201320311658U CN203289096U CN 203289096 U CN203289096 U CN 203289096U CN 2013203116585 U CN2013203116585 U CN 2013203116585U CN 201320311658 U CN201320311658 U CN 201320311658U CN 203289096 U CN203289096 U CN 203289096U
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Abstract
The utility model relates to an overvoltage protective circuit for a composite piezoresistor. The circuit comprises a composite PTC thermistor consisting of a semistor chip and a piezoresistance chip. One end of a gas discharge tube is connected with a first pin and the other end of the gas discharge tube is connected with a second pin. The composite PTC thermistor passes by the first pin and a third pin and is connected with an input terminal of a protected object in parallel. The overvoltage protective circuit provided by the utility model has response speed of the gas discharge tube, circulation capacity of the piezoresistor, residual voltage which is 50 V DC higher than pressure-sensitive residual voltage drop, and relatively high power frequency withstand voltage. A power frequency failure rate of the piezoresistor is reduced and the overvoltage protective circuit can preferably protect the protected object in a manner of the relatively low residual voltage drop.
Description
Technical field
The utility model relates to overvoltage crowbar.
Background technology
Present overvoltage crowbar is by following 3 kinds.
(1) as shown in Figure 1; varistor Rm is a kind of votage limit type protection device; be widely used in various electronic equipments with its excellent non-linear to voltage characteristic, but can even explode because various abnormal causes cause fuse F fusing or piezo-resistance Rm to lose efficacy to catch fire in actual use procedure.
In order to solve this phenomenon; people's have to improve gradually piezo-resistance value of piezo-resistance Rm; perhaps use the fuse F of larger electric current; this will make and improve after the pressure sensitive voltage too high residual voltage and fall protected object is lost protective effect, and perhaps fuse does not fuse and loses the assembling meaning during protected object fault.
(2) as shown in Figure 2; gas discharge tube GDT is a kind of switching mode protection device; pole clearance is with discharge breakdown when two interpolar voltages are enough large; transfer conducting state to by state of insulation; keep voltage under conducting state very low; because gas discharge tube its " follow current interrupt " ability after repeatedly puncturing reduces, general piezo-resistance and the gas discharge tube of adopting makes up the enforcement protection in the protection scheme of alternating current circuit.
Although this circuit has the circulation capacity of response speed and the piezo-resistance of gas discharge tube; but too high response voltage makes many operation surges lose the clamper chance, and the overvoltage that these operation surges also can make protected object bear is repeatedly impacted and increase inefficacy chance.
(3) as shown in Figure 3, PTC(positive temperature coefficient) the assembling device R that is close together by electrode of thermistor and piezo-resistance.
This assembling device utilizes the protection of PTC thermistor to piezo-resistance; at the response voltage of not worrying to have reduced under the prerequisite that piezo-resistance is damaged piezo-resistance; but due to the existence of PTC thermistor resistance, the high residual voltage when thunder-strike current is flowed through the PTC thermistor is fallen and is made whole circuit lose protective effect when thunderbolt voltage.
All there is following defect in above-mentioned 3 kinds of overvoltage crowbars: piezo-resistance is in implementing the protection process to electronic circuit; when the pressure sensitive voltage selection is on the low side; piezo-resistance itself easily becomes a fault point; when the pressure sensitive voltage selection was higher, high residual voltage was fallen and can be reduced the protection effect of piezo-resistance to protected object.
The utility model content
The purpose of this utility model is to propose a kind of compound varistor overvoltage crowbar; it can solve piezo-resistance in electronic circuit is implemented the protection process; when the pressure sensitive voltage selection is on the low side; piezo-resistance itself easily becomes a fault point; when the pressure sensitive voltage selection was higher, high residual voltage was fallen and can be reduced the problem of piezo-resistance to the protection effect of protected object.
In order to achieve the above object, the technical scheme that adopts of the utility model is as follows:
Compound varistor overvoltage crowbar, it comprises semistor chip, voltage dependent resistor chip and gas discharge tube; Electrode of semistor chip and an electrode of voltage dependent resistor chip link together by scolding tin, form common port, by the second pin, draw; The another side electrode of semistor chip is drawn by the first pin; The another side electrode of voltage dependent resistor chip is drawn by the 3rd pin; Semistor chip and voltage dependent resistor chip form compound PTC themistor; One end of gas discharge tube is connected with the first pin, and the other end of gas discharge tube is connected with the second pin; Compound PTC themistor is in parallel with the input of protected object by the first pin, the 3rd pin.
Preferably, semistor chip and voltage dependent resistor chip are the three terminal devices that is encapsulated in an encapsulated layer.
Need to prove, described protected object is late-class circuit or rear class electronic devices and components.
The utlity model has following beneficial effect:
Overvoltage crowbar of the present utility model has the response speed of gas discharge tube; circulation capacity with varistor; have more pressure-sensitive residual voltage and fall the residual voltage of high 50V DC; has higher industrial frequency withstand voltage; when reducing the piezo-resistance failure rate, with lower residual voltage, fall better protected object is implemented protection.
Description of drawings
Fig. 1 to Fig. 3 is the structural representation of 3 kinds of overvoltage crowbars of prior art;
Fig. 4 is the structural representation of the compound varistor overvoltage crowbar of the utility model preferred embodiment;
Fig. 5 is the structural representation of the compound varistor of Fig. 4.
Embodiment
Below, by reference to the accompanying drawings and embodiment, the utility model is described further.
As shown in Figure 4 and Figure 5, a kind of compound varistor overvoltage crowbar, it comprises positive temperature coefficient (PTC) thermistor chip 5, voltage dependent resistor chip 4 and gas discharge tube 6; Electrode of semistor chip 5 and an electrode of voltage dependent resistor chip 4 link together by scolding tin, form common port, by the second pin 2, draw; The another side electrode of semistor chip 5 is drawn by the first pin 1; The another side electrode of voltage dependent resistor chip 4 is drawn by the 3rd pin 3; Semistor chip 5 and voltage dependent resistor chip 4 form compound PTC themistor; One end of gas discharge tube 6 is connected with the first pin 1, and the other end of gas discharge tube 6 is connected with the second pin 2; Compound PTC themistor is in parallel with the input of protected object by the first pin 1, the 3rd pin 3.
The semistor chip 5 of the present embodiment and voltage dependent resistor chip 4 are the three terminal devices that are encapsulated in an encapsulated layer.
The protected object of the present embodiment can be late-class circuit or rear class electronic devices and components.
The principle of the present embodiment is as follows:
Thunderbolt is an acyclic transient current, and surge current is normally caused by switching transient or induction lightening, and the basic identical just energy of both waveforms varies in size.
Gas discharge tube is a kind of switching mode protection device, and operation principle is gas discharge tube when two interpolar voltages are enough large, and pole clearance is with the similar short circuit of discharge breakdown, and two inter-stage voltages generally only have 20-50VDC.
Piezo-resistance is a kind of non-linear overvoltage semiconductor protection device to voltage-sensitive; when both end voltage during higher than pressure sensitive voltage; the non-linear increase of internal current is limiting voltage on than low amplitude, and the residual voltage of piezo-resistance is fallen must be lower than the withstand voltage level of protected object.
The PTC thermistor is that a kind of resistance varies with temperature and the semiconductor element of nonlinear change; the electric current that flows through or the rising of ambient temperature can make thermistor temp change and then make change in resistance, can make under given conditions resistance 3-4 the order of magnitude that risen be the high-impedance state dividing potential drop and protect special object
Compound PTC themistor is aly by PTC themistor, to be connected scolding tin to connect with varistor and the heat that is coupled; implement a three terminal device of protection according to the integrated protection effect of electric current and voltage; do not worrying under the prerequisite that pressure sensitive voltage damages to have selected lower piezo-resistance to press, can implement better protection to protected object.
In surge voltage below 1000V DC, because the pressure sensitive voltage of piezo-resistance is lower, as long as the surge voltage that piezo-resistance can respond, this circuit all has slight absorption, can suitably alleviate surge voltage to protected repeated stock to picture.
In industrial frequency withstand voltage below 650VAC, due to the thermistor resistance risen 3-4 the order of magnitude bear the overwhelming majority withstand voltage, and piezo-resistance only has small On current to flow through can not to damage, on the PTC thermistor, voltage hangs down and is unlikely to puncture gas discharge tube in parallel with it, this circuit can bear the following power frequency proof voltage of 650VAC for a long time, has reduced the possibility that piezo-resistance breaks down.
When the above surge voltage of 1000VDC or thunderbolt voltage, at first this voltage puncture piezo-resistance.Also flow through simultaneously PTC thermistor and produce simultaneously pressure drop of the electric current of the piezo-resistance of flowing through, when this pressure drop during greater than the puncture voltage of gas discharge tube.Gas discharge tube punctures and is short-circuit condition; the PTC thermistor withdraws from the protection process; the residual voltage that is added in residual voltage on protected object this moment and is piezo-resistance itself is fallen and is added the afterflow of gas discharge tube after breakdown and keep voltage; its maximum flow capacity is equal to the maximum flow capacity of piezo-resistance; response speed is equal to the response speed of gas discharge tube, finally with low residual voltage fall, fast speed, large capacity implement the protection to protected object.
The present embodiment this is by the excess voltage protection after compound PTC thermistor gas discharge tube in parallel compound varistor overvoltage crowbar, and it is a circuit of a compound PTC thermistor by three ends gas discharge tube in parallel on the PTC thermistor.
Comparison by experiment, 2 pin of compound PTC themistor (as shown in Figure 3, be the common port of semistor chip and voltage dependent resistor chip) when unsettled gear piezo-resistance is used, assimilation effect to surge current only has 175A, residual voltage is reduced to 2250V DC, and the lightning wave of 3KV is not had assimilation effect substantially.And the compound varistor overvoltage crowbar of the present embodiment is not subjected to the impact of the PTC thermistor in parallel with gas discharge tube substantially on the assimilation effect of the lightning wave of 3KV, is 3KA, and residual voltage is fallen also lower, is 800V DC left and right.
In sum; compound varistor has the circulation capacity of piezo-resistance; response speed with gas discharge tube; anti-power frequency overvoltage capabilities with PTC thermistor; have the residual voltage slightly higher than twice pressure sensitive voltage; it is with lower response voltage on the basis that reduces the varistor fault, and lower residual voltage is fallen, and with constant through-current capacity, has realized better protection to protected object.So compound varistor overvoltage crowbar is to replace conventional piezo-resistance large power supply to be realized a kind of best protection device of protection.
For a person skilled in the art, can make other various corresponding changes and distortion according to technical scheme described above and design, and these all changes and the distortion all should belong to the protection range of the utility model claim within.
Claims (3)
1. compound varistor overvoltage crowbar, is characterized in that, comprises semistor chip (5), voltage dependent resistor chip (4) and gas discharge tube (6); An electrode of semistor chip (5) is drawn by the first pin (1); An electrode of the another side electrode of semistor chip (5) and voltage dependent resistor chip (4) links together by scolding tin, forms common port, by the second pin (2), draws; The another side electrode of voltage dependent resistor chip (4) is drawn by the 3rd pin (3); Semistor chip (5) and voltage dependent resistor chip (4) form compound PTC themistor; One end of gas discharge tube (6) is connected with the first pin (1), and the other end of gas discharge tube (6) is connected with the second pin (2); Compound PTC themistor is in parallel with the input of protected object by the first pin (1), the 3rd pin (3).
2. compound varistor overvoltage crowbar as claimed in claim 1, is characterized in that, semistor chip (5) and voltage dependent resistor chip (4) are the three terminal devices that is encapsulated in an encapsulated layer.
3. compound varistor overvoltage crowbar as claimed in claim 1, is characterized in that, described protected object is late-class circuit or rear class electronic devices and components.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013203116585U CN203289096U (en) | 2013-05-31 | 2013-05-31 | Overvoltage protective circuit for composite piezoresistor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013203116585U CN203289096U (en) | 2013-05-31 | 2013-05-31 | Overvoltage protective circuit for composite piezoresistor |
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| Publication Number | Publication Date |
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| CN203289096U true CN203289096U (en) | 2013-11-13 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2013203116585U Expired - Lifetime CN203289096U (en) | 2013-05-31 | 2013-05-31 | Overvoltage protective circuit for composite piezoresistor |
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| CN (1) | CN203289096U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103311914B (en) * | 2013-05-31 | 2016-08-10 | 深圳市劲阳电子有限公司 | Overvoltage production circuit of composite type piezoresistor |
-
2013
- 2013-05-31 CN CN2013203116585U patent/CN203289096U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103311914B (en) * | 2013-05-31 | 2016-08-10 | 深圳市劲阳电子有限公司 | Overvoltage production circuit of composite type piezoresistor |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20131113 |