CN203574346U - Current limiting protection circuit - Google Patents
Current limiting protection circuit Download PDFInfo
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- CN203574346U CN203574346U CN201320744328.5U CN201320744328U CN203574346U CN 203574346 U CN203574346 U CN 203574346U CN 201320744328 U CN201320744328 U CN 201320744328U CN 203574346 U CN203574346 U CN 203574346U
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- current
- limiting protection
- protection circuit
- switching tube
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- 238000005070 sampling Methods 0.000 claims abstract description 32
- 230000000087 stabilizing effect Effects 0.000 claims abstract description 19
- 239000004065 semiconductor Substances 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
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Abstract
The utility model relates to a current limiting protection circuit. According to the current limiting protection circuit, a voltage stabilizing circuit is additionally provided, a fixed voltage drop is obtained by employing a voltage dividing resistor, the fixed voltage drop is connected with a voltage drop of a current sampling resistor in series so as to control the conduction of switch tubes together, even though the sampling resistance is low, the threshold voltage of the conduction of the switch tubes can be reached so that current limiting protection can be realized with low sampling resistance and the loss of a power line is effectively reduced. Furthermore, an output terminal of a first switch tube is connected to the ground via a thermistor, and the potential of the output terminal of the first switch tube is reduced with the voltage division of the thermistor so that the influence of temperature rise on the threshold voltage of the switch tubes is compensated, the threshold of current limiting protection is unchanged, and the normal operation of the current limiting protection circuit is guaranteed.
Description
Technical field
The utility model relates to a kind of current-limiting protection circuit.
Background technology
The output overcurrent of DC power supply or current-limiting protection circuit, in tradition application, as shown in Figure 1; comprise two triode VT1 and VT2, sampling resistor RS; adopt sampling resistor Rs sampling, the two ends of sampling resistor are connected with triode VT1, and the conducting that VT2 is controlled in the collector electrode output of VT1 realizes protection.But there is the limitation of following 2 aspects in sort circuit: first is that the resistance of sample resistance can not be too little; if too little; the control end of VT1 is difficult to reach the threshold voltage that makes its conducting; particularly when low current threshold value is protected; whole current-limiting protection circuit is difficult to play current-limiting protection effect, and when sample resistance is larger, can cause the power loss on power line; decrease in efficiency, ripple rises.Second point is that the threshold voltage of triode can change along with the variation of temperature, and the threshold voltage of triode is 0.6-0.7V(silicone tube conventionally), but when temperature raises, its value can decline, and causes overcurrent protection threshold value to decline, and impact is normally used.
Utility model content
The purpose of this utility model is to provide a kind of current-limiting protection circuit; can not be too small to solve sampling resistor in current current-limiting protection circuit; meanwhile, also provide a kind of current-limiting protection circuit with thermistor to solve the raises problem of the overcurrent protection threshold value decline being caused of temperature.
The utility model provides a kind of current-limiting protection circuit for solving the problems of the technologies described above; this current-limiting protection circuit; comprise sampling resistor, the first switching tube and second switch pipe for being connected to load circuit; the two ends of sampling resistor are connected with the input of the first switching tube and one end of voltage stabilizing circuit respectively; the output of the first switching tube is connected with the control end of second switch, between described sampling resistor and the first switch controlled end, is serially connected with voltage stabilizing circuit.
Described voltage stabilizing circuit comprise a reference source and with a reference source the divider resistance that connects, the grid control end of the first switching tube is connected with the bleeder circuit node that a reference source produces.
The output of the first described switching tube is by thermistor and current-limiting resistance ground connection.
The first described switching tube and second switch pipe are metal-oxide-semiconductor.
The beneficial effects of the utility model are: the utility model by being connected in series voltage stabilizing circuit between sampling resistor and the first switch controlled end; after utilizing divider resistance that the string in voltage stabilizing circuit is established to be connected in series with sampling resistor, sample; under divider resistance effect in sampling resistor and voltage stabilizing circuit; even if sampling resistor is little; also can reach the threshold voltage of switching tube conducting; thereby the object that hour also can realize current-limiting protection at sampling resistor, reduces the loss on power line.Further; by thermistor ground connection, make the first switching tube output depress potential drop in dividing of thermistor low the first switching tube output, thus the impact that compensation temperature raises on switch pipe threshold voltage; make current-limiting protection threshold value constant, assurance current-limiting protection circuit is normally worked.
Accompanying drawing explanation
Fig. 1 is the structure chart of existing current-limiting protection circuit;
Fig. 2 is the structure chart of the current-limiting protection circuit in the utility model embodiment mono-;
Fig. 3 is the structure chart of the current-limiting protection circuit in the utility model embodiment bis-.
Embodiment
Current-limiting protection circuit of the present utility model comprises sampling resistor, the first switching tube and second switch pipe, the two ends of sampling resistor are connected with control end with the input of the first switching tube respectively, the output of the first switching tube is connected with the control end of second switch, by be connected in series voltage stabilizing circuit between sampling resistor and the first switch controlled end, when DC power supply output current is excessive or current limliting needs protection, sampling after the divider resistance that sampling resistor is established with the string in voltage stabilizing circuit is connected in series, under divider resistance effect in sampling resistor and voltage stabilizing circuit, the voltage of the control end of the first switching tube reaches the threshold voltage of switching tube conducting, now the first switching tube conducting, the output end voltage of the first switching tube raises, and the output of the first switching tube is connected with the control end of second switch pipe, the also corresponding rising of the voltage of second switch pipe control end, the cut-off of second switch pipe, whole circuit is by obstructed, thereby realize the object that hour also can realize current-limiting protection at sampling resistor.
Embodiment mono-
The first switching tube in the present embodiment and second switch pipe are take PMOS pipe as example, as shown in Figure 2, current-limiting protection circuit of the present utility model comprises two PMOS pipe T1 and T2, sampling resistor Rs and voltage stabilizing circuit, one end of sampling resistor Rs is connected with the source electrode of PMOS pipe T1, the other end is connected with the grid of PMOS pipe T1 by voltage stabilizing circuit, the voltage stabilizing circuit here comprises a reference source U1, R2, R3 and R4, R2 and R3 are connected in series afterwards and are connected to the anode and cathode two ends of U1, the reference edge of U1 is connected to cathode terminal, the drain electrode of PMOS pipe T1 is connected with the grid of PMOS pipe T2, the source electrode of PMOS pipe T2 is connected in main current path with drain electrode.According to the line drop of the protective current threshold value that will set and permission, select Rs; According to the voltage stabilizing value of the transfer characteristic of T1 and a reference source U1, selected resistance R 2, R3.
The operation principle of this circuit is as follows: when DC power supply output current is excessive or current limliting needs protection, sampling after electric current is connected in series with the divider resistance R2 establishing with the string in voltage stabilizing circuit after sampling resistor RS, under divider resistance R2 effect in sampling resistor Rs and voltage stabilizing circuit, the grid voltage of PMOS pipe T1 reaches the threshold voltage of PMOS pipe conducting, PMOS pipe T1 conducting gradually, the current potential of the drain electrode of PMOS pipe T1 raises gradually, and the drain electrode of PMOS pipe T1 is connected with the grid of PMOS pipe T2, the grid voltage that is PMOS pipe T2 raises gradually, PMOS pipe T2 is tending towards turn-offing gradually, main current path will be stabilized in a limiting current value, thereby realize the object that hour also can realize current-limiting protection at sampling resistor.
Embodiment bis-
Ambient temperature rising can cause the threshold voltage of switching tube conducting to decline; now; in current-limiting protection circuit, because can making current-limiting protection circuit, the threshold voltage decline of switching tube conducting enters in advance guard mode; can not normally use; for this reason; on the basis of embodiment mono-; done further improvement; as shown in Figure 3; ground connection after the drain electrode end of PMOS pipe T1 is connected in series a thermistor VR1 and current-limiting resistance R1; by the effect of thermistor VR1 and resistance R 1, when compensation temperature raises, metal-oxide-semiconductor threshold voltage reduces the impact that circuit is caused.Its operation principle is as follows: while not reaching current limit threshold, if temperature raises, the threshold voltage of PMOS pipe T1 reduces, PMOS pipe T1 enters conducting state in advance, the T1 ground that drains produces Weak current, the voltage drop meeting that this electric current produces in thermistor VR1 and resistance R 1 reduces, and maintains the substantially constant effect of T1 drain potential, otherwise has contrary adjustment effect when ambient temperature reduces.No matter how temperature changes, and within the specific limits, current-limiting circuit can normally be used.
Claims (4)
1. a current-limiting protection circuit; comprise sampling resistor, the first switching tube and second switch pipe for being connected to load circuit; the two ends of sampling resistor are connected with the input of the first switching tube and one end of voltage stabilizing circuit respectively; the output of the first switching tube is connected with the control end of second switch; it is characterized in that, between described sampling resistor and the first switch controlled end, be serially connected with voltage stabilizing circuit.
2. current-limiting protection circuit according to claim 1, is characterized in that, described voltage stabilizing circuit comprise a reference source and with a reference source the divider resistance that connects, the grid control end of the first switching tube is connected with the bleeder circuit node that a reference source produces.
3. current-limiting protection circuit according to claim 1, is characterized in that, the output of the first described switching tube is by thermistor and current-limiting resistance ground connection.
4. according to the current-limiting protection circuit described in claim 1,2 or 3, it is characterized in that, the first described switching tube and second switch pipe are metal-oxide-semiconductor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320744328.5U CN203574346U (en) | 2013-11-22 | 2013-11-22 | Current limiting protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320744328.5U CN203574346U (en) | 2013-11-22 | 2013-11-22 | Current limiting protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203574346U true CN203574346U (en) | 2014-04-30 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201320744328.5U Expired - Lifetime CN203574346U (en) | 2013-11-22 | 2013-11-22 | Current limiting protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203574346U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103595016A (en) * | 2013-11-22 | 2014-02-19 | 郑州光力科技股份有限公司 | Current-limiting protection circuit |
-
2013
- 2013-11-22 CN CN201320744328.5U patent/CN203574346U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103595016A (en) * | 2013-11-22 | 2014-02-19 | 郑州光力科技股份有限公司 | Current-limiting protection circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CP01 | Change in the name or title of a patent holder | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 450001 Henan city of Zhengzhou province high tech Industrial Development Zone Long Chun Road No. 10 Patentee after: GLTECH Co.,Ltd. Address before: 450001 Henan city of Zhengzhou province high tech Industrial Development Zone Long Chun Road No. 10 Patentee before: ZHEJIANG GUANGLI TECH DEVELOPMENT Co.,Ltd. |
|
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20140430 |