CN103457251A - Protective circuit based on PTC thermistor - Google Patents
Protective circuit based on PTC thermistor Download PDFInfo
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- CN103457251A CN103457251A CN2013103925724A CN201310392572A CN103457251A CN 103457251 A CN103457251 A CN 103457251A CN 2013103925724 A CN2013103925724 A CN 2013103925724A CN 201310392572 A CN201310392572 A CN 201310392572A CN 103457251 A CN103457251 A CN 103457251A
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- ptc thermistor
- protective circuit
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Abstract
The invention discloses a protective circuit based on a PTC thermistor. The protective circuit based on the PTC thermistor comprises a zinc oxide piezoresistor, the PTC thermistor, a temperature fuse and a protected circuit, wherein the protected circuit and the zinc oxide piezoresistor are connected in parallel and then are connected with the PTC thermistor and the temperature fuse in series. According to the protective circuit based on the PTC thermistor, overvoltage protection, overcurrent protection and overload protection can be achieved at the same time, thermal runaway, caused by over-high temperature, of the thermistor is effectively avoided, potential safety hazards which are caused by the potential failure mode of the PTC thermistor are effectively avoided, safety performance is improved, the protection speed of the PTC thermistor is improved, influence of environment temperature on the protection speed of the PTC thermistor is reduced, the circuit structure is simple and cost is low. The protective circuit based on the PTC thermistor is suitable for being popularized widely.
Description
Technical field
The invention belongs to the electronic circuit technology field, more specifically, relate to a kind of protective circuit based on the PTC thermistor.
Background technology
Positive temperature coefficient (Positive Temperature Coefficient, PTC) thermistor is widely used in the circuit protection in the 6C industrial fields such as computer, communication, consumer electronics, automobile, path, digital content.Its operation principle is: when circuit works, PTC thermistor resistance is very little, does not hinder electric current and passes through; And, when overcurrent, overload or the fault such as overheated appear in circuit, PTC thermistor gauge surface temperature rises rapidly, while surpassing switch temperature, its resistance moment rises to high-impedance state, in time circuital current is limited in to very low level, with protective circuit.After fault is got rid of, the PTC thermistor is cooling and return to former low resistive state rapidly, reusable.
Current overcurrent/overtemperature protection system generally adopts the PTC thermistor.The PTC thermistor do not get rid of at fault, under long-time "on" position, because aftercurrent being arranged himself by generating heat, cause accumulation of heat, and its potential failure mode is burning.The characteristic of semistor determines, after himself macromolecular material burning, there is certain probability conducting in the two ends metal electrode material, forms short circuit, damages circuit, has larger potential safety hazard.
Zinc-oxide piezoresistor has nonlinear voltage-current characteristic; generally in electronic circuit, be used as anti-overvoltage, lightning-preventing protector part; its operation principle is: varistor is connected on protected circuit; when line voltage distribution lower than the operational voltage value of piezo-resistance is; the resistance of varistor is high, is close to open circuit, thereby can not affect the normal operation of device or electric equipment.When voltage instantaneous higher than a certain numerical value is, the resistance of varistor descends rapidly, the large electric current of conducting, by voltage clamp in the voltage range that protected device or electric equipment can bear, thereby protection protected device or electric equipment.Yet Zinc-oxide piezoresistor absorbs energy when conducting, himself temperature raises rapidly, and therefore, during the piezo-resistance conducting, absorbent energy is limited, if energy is crossed senior general, causes the piezo-resistance excess Temperature and is lost efficacy by thermal breakdown.
Summary of the invention
Above defect or Improvement requirement for prior art; the invention provides a kind of protective circuit based on the PTC thermistor; can carry out overvoltage, overcurrent and overload protection simultaneously; effectively avoid piezo-resistance because of excess Temperature by thermal breakdown; effectively avoid the PTC thermistor potential safety hazard that potential failure mode is brought to occur, improve security performance simultaneously.
For achieving the above object, according to one aspect of the present invention, provide a kind of protective circuit based on the PTC thermistor, it is characterized in that, having comprised: Zinc-oxide piezoresistor, PTC thermistor, Thermal Cutoffs and protected circuit; Described protected circuit is with after described Zinc-oxide piezoresistor is in parallel, then connects with described PTC thermistor and described Thermal Cutoffs.
In general, the above technical scheme of conceiving by the present invention compared with prior art, has following beneficial effect:
1, the heat of piezo-resistance conducting heating is passed to rapidly to the PTC thermistor, the resistance Yin Wendu of PTC thermistor raises and increases rapidly, avoid piezo-resistance because of excess Temperature by thermal breakdown, greatly improved the reliability of thermistor.
2, the temperature of the disconnected temperature of hot melt of selecting Thermal Cutoffs during a little less than the potential failure mode of PTC thermistor, once the PTC thermistor hinders for some reason and fails to get rid of in time and potential failure mode occurs, Thermal Cutoffs fusing, cut off circuit fully, improves security performance.
3, piezo-resistance and the thermal coupling of PTC thermistor, accelerated the protection speed of PTC thermistor, and the protection speed that has reduced the PTC thermistor is subject to the impact of ambient temperature.
4, circuit structure is simple, cost is low, is suitable for large-scale promotion application.
The accompanying drawing explanation
Fig. 1 is the protective circuit structural representation based on the PTC thermistor of the embodiment of the present invention.
Embodiment
In order to make purpose of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.In addition, below in each execution mode of described the present invention involved technical characterictic as long as form each other conflict, just can mutually not combine.
As shown in Figure 1, the protective circuit based on the PTC thermistor of the embodiment of the present invention comprises: Zinc-oxide piezoresistor 1, PTC thermistor 2, Thermal Cutoffs 3 and protected circuit.Protected circuit is with after Zinc-oxide piezoresistor 1 is in parallel, then connects with PTC thermistor 2 and Thermal Cutoffs 3.
When overpressure conditions occurring; Zinc-oxide piezoresistor 1 conducting heating; heat passes to rapidly the PTC thermistor 2 with Zinc-oxide piezoresistor 1 thermal coupling; the rising of the resistance Yin Wendu of PTC thermistor 2 and increasing rapidly; protection Zinc-oxide piezoresistor 1; avoid Zinc-oxide piezoresistor 1 because of excess Temperature by thermal breakdown, greatly improved the reliability of Zinc-oxide piezoresistor.
When overcurrent or overload conditions occurring, the resistance of PTC thermistor raises rapidly, and circuital current is limited in to very low level, protective circuit.Piezo-resistance and the thermal coupling of PTC thermistor, accelerated the protection speed of PTC thermistor, and the protection speed that has reduced the PTC thermistor is subject to the impact of ambient temperature.
The protective circuit based on the PTC thermistor of the embodiment of the present invention can be carried out overvoltage, overcurrent and overload protection simultaneously; effectively avoid piezo-resistance because of excess Temperature by thermal breakdown; effectively avoid the PTC thermistor potential safety hazard that potential failure mode is brought to occur simultaneously; improve security performance; accelerated the protection speed of PTC thermistor; the protection speed that has reduced the PTC thermistor is subject to the impact of ambient temperature, and circuit structure is simple, cost is low, is suitable for large-scale promotion application.
Those skilled in the art will readily understand; the foregoing is only preferred embodiment of the present invention; not in order to limit the present invention, all any modifications of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.
Claims (1)
1. the protective circuit based on the PTC thermistor, is characterized in that, comprising: Zinc-oxide piezoresistor, PTC thermistor, Thermal Cutoffs and protected circuit; Described protected circuit is with after described Zinc-oxide piezoresistor is in parallel, then connects with described PTC thermistor and described Thermal Cutoffs.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013103925724A CN103457251A (en) | 2013-08-30 | 2013-08-30 | Protective circuit based on PTC thermistor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013103925724A CN103457251A (en) | 2013-08-30 | 2013-08-30 | Protective circuit based on PTC thermistor |
Publications (1)
| Publication Number | Publication Date |
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| CN103457251A true CN103457251A (en) | 2013-12-18 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2013103925724A Pending CN103457251A (en) | 2013-08-30 | 2013-08-30 | Protective circuit based on PTC thermistor |
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| CN (1) | CN103457251A (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104392871A (en) * | 2014-11-14 | 2015-03-04 | 华南理工大学 | Residual-current circuit breaker with overvoltage protection function |
| CN105098742A (en) * | 2014-04-29 | 2015-11-25 | 瑞侃电子(上海)有限公司 | Current balance control unit, electric appliance part, electric appliance component and circuit |
| CN105186476A (en) * | 2015-09-24 | 2015-12-23 | 湖南劲阳电子有限公司 | Overvoltage and overcurrent protection circuit |
| CN105186477A (en) * | 2015-09-24 | 2015-12-23 | 湖南劲阳电子有限公司 | Overvoltage and overcurrent protection circuit |
| CN105633937A (en) * | 2016-02-29 | 2016-06-01 | 长沙群瑞电子科技有限公司 | Single-phase power supply series-wound type overvoltage protector |
| CN109612599A (en) * | 2019-01-04 | 2019-04-12 | 胡靖阳 | A kind of temperature sensor of built-in self-shield |
| CN110336264A (en) * | 2019-08-22 | 2019-10-15 | 成都铁达电子股份有限公司 | A kind of pressure limiting circuit |
| CN111383869A (en) * | 2018-12-29 | 2020-07-07 | 安波福电子(苏州)有限公司 | Novel fuse box with large current and fuse fusing early warning function |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102403711A (en) * | 2011-11-17 | 2012-04-04 | 溧阳杰敏电子有限公司 | Resettable fuse type self protection overvoltage overcurrent protection circuit |
| CN102403710A (en) * | 2011-11-16 | 2012-04-04 | 溧阳杰敏电子有限公司 | Thermistor type overvoltage/overcurrent protection circuit |
| CN202282601U (en) * | 2011-11-12 | 2012-06-20 | 袁毅 | Protection circuit combining high-polymer phenylthiocarbamide (PTC) thermistor and piezoresistor |
-
2013
- 2013-08-30 CN CN2013103925724A patent/CN103457251A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202282601U (en) * | 2011-11-12 | 2012-06-20 | 袁毅 | Protection circuit combining high-polymer phenylthiocarbamide (PTC) thermistor and piezoresistor |
| CN102403710A (en) * | 2011-11-16 | 2012-04-04 | 溧阳杰敏电子有限公司 | Thermistor type overvoltage/overcurrent protection circuit |
| CN102403711A (en) * | 2011-11-17 | 2012-04-04 | 溧阳杰敏电子有限公司 | Resettable fuse type self protection overvoltage overcurrent protection circuit |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105098742A (en) * | 2014-04-29 | 2015-11-25 | 瑞侃电子(上海)有限公司 | Current balance control unit, electric appliance part, electric appliance component and circuit |
| CN104392871A (en) * | 2014-11-14 | 2015-03-04 | 华南理工大学 | Residual-current circuit breaker with overvoltage protection function |
| CN105186476A (en) * | 2015-09-24 | 2015-12-23 | 湖南劲阳电子有限公司 | Overvoltage and overcurrent protection circuit |
| CN105186477A (en) * | 2015-09-24 | 2015-12-23 | 湖南劲阳电子有限公司 | Overvoltage and overcurrent protection circuit |
| CN105186476B (en) * | 2015-09-24 | 2019-04-16 | 湖南劲阳电子有限公司 | A kind of over-voltage over-current protection circuit |
| CN105633937A (en) * | 2016-02-29 | 2016-06-01 | 长沙群瑞电子科技有限公司 | Single-phase power supply series-wound type overvoltage protector |
| CN111383869A (en) * | 2018-12-29 | 2020-07-07 | 安波福电子(苏州)有限公司 | Novel fuse box with large current and fuse fusing early warning function |
| CN109612599A (en) * | 2019-01-04 | 2019-04-12 | 胡靖阳 | A kind of temperature sensor of built-in self-shield |
| CN110336264A (en) * | 2019-08-22 | 2019-10-15 | 成都铁达电子股份有限公司 | A kind of pressure limiting circuit |
| CN110336264B (en) * | 2019-08-22 | 2024-01-26 | 成都铁达电子股份有限公司 | Voltage limiting circuit |
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Application publication date: 20131218 |