CN104218521A - A low voltage protection circuit - Google Patents
A low voltage protection circuit Download PDFInfo
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- CN104218521A CN104218521A CN201310211112.7A CN201310211112A CN104218521A CN 104218521 A CN104218521 A CN 104218521A CN 201310211112 A CN201310211112 A CN 201310211112A CN 104218521 A CN104218521 A CN 104218521A
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- voltage
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- protection circuit
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Abstract
A low voltage protection circuit is provided in this invention. The circuit includes a low voltage sampling resistor, a high voltage sampling resistor, a third resistor, a filter capacitor, a P channel enhancement MOS transistor, a NPN triode, a voltage stabilizing diode and a diode; the source electrode of the P channel enhancement MOS transistor is coupled with an input power source, one end of the low voltage sampling resistor and one end of the high voltage sampling resistor; the the drain electrode of the P channel enhancement MOS transistor is coupled with an power source output end; the the grid electrode of the P channel enhancement MOS transistor is coupled with the collector of NPN triode and the other end of the high voltage sampling resistor; the other end of the low voltage sampling diode is coupled with the negative electrode of the voltage stabilizing diode and one end of the filter capacitor; the other end of the filter capacitor is grounded; the positive electrode of the voltage stabilizing diode is coupled with the positive electrode of diode; the negative electrode is coupled with the base of NPN triode and one end of the third resistor; the other end of the third resistor is grounded, the emitting electrode of the NPN triode is grounded. This low voltage protection circuit is able to cut off the power source automatically when the voltage is excessively low and protect the safety of the product and human.
Description
Technical field
The present invention relates to protective circuit field, particularly a kind of low-voltage protection circuit to the conditional electronic product of operating voltage range.
Background technology
A lot of electronic product needs external power supply at present, and product all can have strict requirement to external supply voltage scope, can not exceed voltage range and use.If but user is unclear or not strict use or extraneous line voltage on request uprise suddenly, as external power supply brownout will damage product, produces unpredictable danger.Power supply low pressure input protection circuit is proposed, this circuit protection fast response time and precisely reliable for this reason.
In view of this, a kind of low-voltage protection circuit is inventor provided.
Summary of the invention
For defect of the prior art, the invention provides a kind of low-voltage protection circuit, overcome the difficulty of prior art, can cross low pressure time automatic cut-off power, the safety of protection product and the person, and owing to all adopting discrete part to form, without the need to integrated circuit, can product cost be reduced, save the space of printed circuit board (PCB); Circuit of the present invention simply can lean on by height, and threshold voltage is arranged conveniently.
According to an aspect of the present invention, a kind of low-voltage protection circuit is provided, comprises: a low pressure sample resistance, a high-voltage sampling resistance, one the 3rd resistance, a filter capacitor, a P-channel enhancement type metal-oxide-semiconductor, a NPN type triode, a voltage stabilizing didoe and a diode;
The source electrode of described P-channel enhancement type metal-oxide-semiconductor couples input power, one end of described low pressure sample resistance and one end of described high-voltage sampling resistance;
The drain electrode of described P-channel enhancement type metal-oxide-semiconductor couples voltage output end;
The grid of described P-channel enhancement type metal-oxide-semiconductor couples the collector electrode of described NPN type triode and the other end of described high-voltage sampling resistance;
The other end of described low pressure sample resistance couples the negative pole of described voltage stabilizing didoe and one end of described filter capacitor;
The other end ground connection of described filter capacitor;
The positive pole of described voltage stabilizing didoe couples the positive pole of described diode;
The negative pole of described diode couples the base stage of described NPN type triode and one end of described 3rd resistance;
The other end ground connection of described 3rd resistance, the grounded emitter of described NPN type triode.
Preferably, the polar capacitor of a low-voltage protection circuit outside is also coupled between the earth terminal of described filter capacitor and the source electrode of described P-channel enhancement type metal-oxide-semiconductor.
Preferably, the positive pole of described polar capacitor couples the source electrode of described P-channel enhancement type metal-oxide-semiconductor, minus earth.
Preferably, a bridge rectifier is also coupled between the source electrode of described input power and described P-channel enhancement type metal-oxide-semiconductor.
Preferably, described input power is AC power.
Preferably, the sampling voltage of described low pressure sample resistance takes from the input power after described bridge rectifier rectification, when described sampling voltage is after described low pressure sample resistance, filter capacitor filtering, when the breakdown voltage value that described sampling voltage is less than described voltage stabilizing didoe adds the conducting voltage of described diode and the base stage of described NPN type triode to the summation of the pressure drop of emitter, described NPN type triode cut-off, then described P-channel enhancement type metal-oxide-semiconductor is also cut off.
Preferably, described input power is DC power supply.
Compared with prior art, owing to employing above technology, low-voltage protection circuit of the present invention can cross low pressure time automatic cut-off power, the safety of protection product and the person, and owing to all adopting discrete part to form, without the need to integrated circuit, can product cost be reduced, save the space of printed circuit board (PCB); Circuit of the present invention simply can lean on by height, and threshold voltage is arranged conveniently.
Accompanying drawing explanation
By reading the detailed description done non-limiting example with reference to the following drawings, other features, objects and advantages of the present invention will become more obvious:
Fig. 1 illustrates according to a specific embodiment of the present invention, the circuit diagram of low-voltage protection circuit of the present invention.
Reference numeral
1 low pressure sample resistance
2 high-voltage sampling resistances
3 the 3rd resistance
4 filter capacitors
5 P-channel enhancement type metal-oxide-semiconductors
6 NPN type triode
7 voltage stabilizing didoes
8 diodes
10 voltage output ends
11 bridge rectifiers
12 input powers
13 polar capacitors
100 low-voltage protection circuits
Embodiment
It will be appreciated by those skilled in the art that those skilled in the art can realize change case in conjunction with prior art and above-described embodiment, do not repeat them here.Such change case does not affect flesh and blood of the present invention, does not repeat them here.
Fig. 1 illustrates according to a specific embodiment of the present invention, the circuit diagram of low-voltage protection circuit of the present invention.As shown in Figure 1, a kind of low-voltage protection circuit 100 of the present invention, comprising: low pressure sample resistance 1, high-voltage sampling resistance 2, the 3rd resistance 3, filter capacitor 4, P-channel enhancement type metal-oxide-semiconductor 5, NPN type triode 6, voltage stabilizing didoe 7 and diode 8.The source electrode of P-channel enhancement type metal-oxide-semiconductor 5 couples input power 12, one end of low pressure sample resistance 1 and one end of high-voltage sampling resistance 2.The drain electrode of P-channel enhancement type metal-oxide-semiconductor 5 couples voltage output end 10.The grid of P-channel enhancement type metal-oxide-semiconductor 5 couples the collector electrode of NPN type triode 6 and the other end of high-voltage sampling resistance 2.The other end of low pressure sample resistance 1 couples the negative pole of voltage stabilizing didoe 7 and one end of filter capacitor 4.The other end ground connection of filter capacitor 4.The positive pole of voltage stabilizing didoe 7 couples the positive pole of diode 8.The negative pole of diode 8 couples the base stage of NPN type triode 6 and one end of the 3rd resistance 3.The other end ground connection of the 3rd resistance 3.The grounded emitter of NPN type triode 6.
Also couple the polar capacitor 13 of low-voltage protection circuit 100 outside between the earth terminal of filter capacitor 4 and the source electrode of P-channel enhancement type metal-oxide-semiconductor 5, wherein, the positive pole of polar capacitor 13 couples the source electrode of P-channel enhancement type metal-oxide-semiconductor 5, minus earth.
The circuit that low-voltage protection circuit 100 of the present invention can be DC power supply for input power 12 carries out low-voltage variation, and the circuit that can be also AC power for input power 12 carries out low-voltage variation.When input power 12 is AC power, a bridge rectifier 11 of can connecting between input power 12 and the source electrode of P-channel enhancement type metal-oxide-semiconductor 5.
The sampling voltage of low pressure sample resistance 1 takes from the input power 12 after bridge rectifier 11 rectification, when sampling voltage is after low pressure sample resistance 1, filter capacitor 4 filtering, when the breakdown voltage value that sampling voltage is less than voltage stabilizing didoe 7 adds the conducting voltage of diode 8 and the base stage of NPN type triode to the summation of the pressure drop of emitter, NPN type triode is ended, then P-channel enhancement type metal-oxide-semiconductor is also cut off.
The operation principle of low-voltage protection circuit of the present invention is as follows:
The input voltage of low pressure sample resistance 1 takes from the input power after rectification; sampling voltage is after low pressure sample resistance 1, filter capacitor 4 filtering; when the breakdown voltage value that voltage is less than voltage-stabiliser tube adds the conducting voltage of diode and the base stage of NPN type triode 6 to the summation of the pressure drop of emitter; NPN type triode 6 will be ended; the condition of its conducting that P-channel enhancement type metal-oxide-semiconductor can not arrive: VGS(th) < 0, thus realize low-voltage variation.
Be 14V as wanted the minimum operating voltage of initialization circuit; then voltage stabilizing didoe 7 can select puncture voltage to be the voltage stabilizing didoe of 12.4V; IN4148 type diode selected by diode 8; can arrange the electric current flowing through low pressure sample resistance 1 is 2mA; the base stage Ib of NPN type triode 6 is also 2mA; NPN type triode 6 can be made to enter saturation conduction state; so resistance value is (14-12.5-0.7-0.7)/2=50 Ω; when the voltage that can realize input power is like this greater than 14V, circuit normally works, lower than entering low-voltage variation state during 14V.Pressure drop on resistance low pressure sample resistance 1 determines the precision of protection voltage, and as above the precision of voltage value is about 0.1V.Then 14V can circuit working, and during 13.8V, circuit enters guard mode.
Low-voltage protection circuit 100 of the present invention to be used in a portable fluorescent lamp light fixture after power supply input protection part.After connecting external power supply; extraneous supply voltage is after rectifying and wave-filtering; low-voltage protection circuit 100 is entered respectively after low pressure sample resistance 1 and high-voltage sampling resistance 2; sampling voltage controls the break-make of NPN type triode 6 after relatively; thus control the break-make of P-channel enhancement type metal-oxide-semiconductor; realize low-voltage variation function, make florescent lamp fitting be in work or guard mode.
In summary, low-voltage protection circuit of the present invention can when crossing low pressure automatic cut-off power, protection product and the safety of the person, and owing to all adopting discrete part form, without the need to integrated circuit, can product cost be reduced, the space of saving printed circuit board (PCB); Circuit of the present invention simply can lean on by height, and threshold voltage is arranged conveniently.
Above specific embodiments of the invention are described.It is to be appreciated that the present invention is not limited to above-mentioned particular implementation, those skilled in the art can make various distortion or amendment within the scope of the claims, and this does not affect flesh and blood of the present invention.
Claims (7)
1. a low-voltage protection circuit, is characterized in that, comprising: a low pressure sample resistance, a high-voltage sampling resistance, one the 3rd resistance, a filter capacitor, a P-channel enhancement type metal-oxide-semiconductor, a NPN type triode, a voltage stabilizing didoe and a diode;
The source electrode of described P-channel enhancement type metal-oxide-semiconductor couples input power, one end of described low pressure sample resistance and one end of described high-voltage sampling resistance;
The drain electrode of described P-channel enhancement type metal-oxide-semiconductor couples voltage output end;
The grid of described P-channel enhancement type metal-oxide-semiconductor couples the collector electrode of described NPN type triode and the other end of described high-voltage sampling resistance;
The other end of described low pressure sample resistance couples the negative pole of described voltage stabilizing didoe and one end of described filter capacitor;
The other end ground connection of described filter capacitor;
The positive pole of described voltage stabilizing didoe couples the positive pole of described diode;
The negative pole of described diode couples the base stage of described NPN type triode and one end of described 3rd resistance;
The other end ground connection of described 3rd resistance, the grounded emitter of described NPN type triode.
2. low-voltage protection circuit as claimed in claim 1, is characterized in that: the polar capacitor also coupling a low-voltage protection circuit outside between the earth terminal of described filter capacitor and the source electrode of described P-channel enhancement type metal-oxide-semiconductor.
3. low-voltage protection circuit as claimed in claim 2, is characterized in that: the positive pole of described polar capacitor couples the source electrode of described P-channel enhancement type metal-oxide-semiconductor, minus earth.
4. low-voltage protection circuit as claimed in claim 3, is characterized in that: also couple a bridge rectifier between the source electrode of described input power and described P-channel enhancement type metal-oxide-semiconductor.
5. low-voltage protection circuit as claimed in claim 4, is characterized in that: described input power is AC power.
6. low-voltage protection circuit as claimed in claim 5; it is characterized in that: the sampling voltage of described low pressure sample resistance takes from the input power after described bridge rectifier rectification; when described sampling voltage is after described low pressure sample resistance, filter capacitor filtering; when the breakdown voltage value that described sampling voltage is less than described voltage stabilizing didoe adds the conducting voltage of described diode and the base stage of described NPN type triode to the summation of the pressure drop of emitter; described NPN type triode cut-off, then described P-channel enhancement type metal-oxide-semiconductor is also cut off.
7. low-voltage protection circuit as claimed in claim 3, is characterized in that: described input power is DC power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310211112.7A CN104218521A (en) | 2013-05-30 | 2013-05-30 | A low voltage protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310211112.7A CN104218521A (en) | 2013-05-30 | 2013-05-30 | A low voltage protection circuit |
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| Publication Number | Publication Date |
|---|---|
| CN104218521A true CN104218521A (en) | 2014-12-17 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310211112.7A Pending CN104218521A (en) | 2013-05-30 | 2013-05-30 | A low voltage protection circuit |
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| CN (1) | CN104218521A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104834241A (en) * | 2015-05-15 | 2015-08-12 | 深圳市施美森科技有限公司 | Digital input circuit |
| CN108494247A (en) * | 2018-04-28 | 2018-09-04 | 惠州市德赛西威汽车电子股份有限公司 | A kind of power circuit for taking into account 180V high voltage protectives and 5V operating on low voltage |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101867168A (en) * | 2010-05-21 | 2010-10-20 | 海洋王照明科技股份有限公司 | Power protecting circuit and LED lamp |
| CN202373957U (en) * | 2011-12-28 | 2012-08-08 | 东莞市茂扬科技股份有限公司 | Over-voltage and under-voltage protection circuit |
| CN102780204A (en) * | 2011-05-10 | 2012-11-14 | 海洋王照明科技股份有限公司 | Under-voltage protection circuit and lamp |
-
2013
- 2013-05-30 CN CN201310211112.7A patent/CN104218521A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101867168A (en) * | 2010-05-21 | 2010-10-20 | 海洋王照明科技股份有限公司 | Power protecting circuit and LED lamp |
| CN102780204A (en) * | 2011-05-10 | 2012-11-14 | 海洋王照明科技股份有限公司 | Under-voltage protection circuit and lamp |
| CN202373957U (en) * | 2011-12-28 | 2012-08-08 | 东莞市茂扬科技股份有限公司 | Over-voltage and under-voltage protection circuit |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104834241A (en) * | 2015-05-15 | 2015-08-12 | 深圳市施美森科技有限公司 | Digital input circuit |
| CN104834241B (en) * | 2015-05-15 | 2018-01-23 | 深圳市施美森科技有限公司 | Digital input circuit |
| CN108494247A (en) * | 2018-04-28 | 2018-09-04 | 惠州市德赛西威汽车电子股份有限公司 | A kind of power circuit for taking into account 180V high voltage protectives and 5V operating on low voltage |
| CN108494247B (en) * | 2018-04-28 | 2019-12-17 | 惠州市德赛西威汽车电子股份有限公司 | Power supply circuit giving consideration to 180V high-voltage protection and 5V low-voltage work |
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| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20141217 |
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| WD01 | Invention patent application deemed withdrawn after publication |