CN214543597U - Short-circuit protection circuit and printer - Google Patents
Short-circuit protection circuit and printer Download PDFInfo
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- CN214543597U CN214543597U CN202120308650.8U CN202120308650U CN214543597U CN 214543597 U CN214543597 U CN 214543597U CN 202120308650 U CN202120308650 U CN 202120308650U CN 214543597 U CN214543597 U CN 214543597U
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- 238000005070 sampling Methods 0.000 claims abstract description 36
- 239000003990 capacitor Substances 0.000 claims description 31
- 229910044991 metal oxide Inorganic materials 0.000 claims 1
- 150000004706 metal oxides Chemical class 0.000 claims 1
- 239000004065 semiconductor Substances 0.000 claims 1
- 230000000694 effects Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 230000001960 triggered effect Effects 0.000 description 1
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Abstract
The utility model relates to a circuit technical field. The utility model discloses a short-circuit protection circuit and printer, wherein, short-circuit protection circuit includes current sampling circuit, current spike removing circuit, filter circuit, comparison circuit and switch circuit, and switch circuit concatenates in treating the protection return circuit, and current sampling circuit is used for the sampling to treat the electric current size in protection return circuit, and current sampling circuit's output loops through current spike removing circuit and filter circuit and connects comparison circuit's input, and comparison circuit's output termination switch circuit's control end. The utility model discloses can set up more accurate protection threshold current value, provide reliable current protection, and can avoid single or continuous pulse current to influence protection circuit, avoid the false triggering protection, reliability, security and stability are high.
Description
Technical Field
The utility model belongs to the technical field of the circuit, specifically relate to a short-circuit protection circuit and printer to having pulse current.
Background
When the electrical equipment takes place the short circuit, if do not protect in time, can lead to equipment to be burnt out and damaged, cause electrical fire even, cause serious incident, consequently, the electrical equipment of the overwhelming majority all can be equipped with short-circuit protection circuit and carry out short-circuit protection, power supply reentries electrical equipment through short-circuit protection circuit, short-circuit protection circuit sampling power supply loop's electric current is judged, when judging that power supply loop's electric current is greater than protection threshold current, just think the short circuit takes place, thereby drive switch circuit cuts off this power supply loop, stop power supply and continue to supply power for electrical equipment. Pulse current often exists in many electric devices such as printers and the like, including single pulse current and/or continuous pulse current, and a traditional short-circuit protection circuit is often triggered by mistake under the interference of the pulse current, so that the normal use is influenced, and the user experience is reduced; some short-circuit protection circuits improve the current value of a protection threshold in order to avoid false triggering under the interference of pulse current, which causes the setting of the protection threshold to be too high, influences the short-circuit protection effect and reduces the safety and reliability.
Disclosure of Invention
An object of the utility model is to provide a short-circuit protection circuit and printer to having pulse current are used for solving the technical problem that the aforesaid exists.
In order to achieve the above object, the utility model adopts the following technical scheme: a short-circuit protection circuit comprises a current sampling circuit, a current spike removing circuit, a filter circuit, a comparison circuit and a switch circuit, wherein the switch circuit is connected in series in a loop to be protected, the current sampling circuit is used for sampling the current of the loop to be protected, the output end of the current sampling circuit is connected with the input end of the comparison circuit sequentially through the current spike removing circuit and the filter circuit, and the output end of the comparison circuit is connected with the control end of the switch circuit.
Further, the current sampling circuit comprises a sampling resistor R1, and the sampling resistor R1 is connected in series in the loop to be protected.
Furthermore, the current spike removing circuit comprises a capacitor C1, and a capacitor C1 is arranged in parallel with the sampling resistor R1.
Furthermore, the filter circuit is composed of a resistor and a capacitor.
Furthermore, the filter circuit comprises a resistor R3, a resistor R5, a capacitor C3 and a capacitor C4, wherein the resistor R3 and the resistor R5 are connected in series and then connected between the output end of the current spike removing circuit and the input end of the comparison circuit, and two ends of the resistor R5 are grounded through the capacitor C3 and the capacitor C4 respectively.
Further, the comparison circuit is implemented by using a comparator U1A.
Further, the switch circuit comprises a PMOS transistor Q1 and an NPN triode Q2, the PMOS transistor Q1 is connected in series in the loop to be protected, the gate of the PMOS transistor Q1 is connected with the collector of the NPN triode Q2, the emitter of the NPN triode Q2 is grounded, and the base of the NPN triode Q2 is connected with the output end of the comparison circuit.
Furthermore, the switch circuit further comprises a resistor R2 and a capacitor C2, wherein the resistor R2 and the capacitor C2 are connected in parallel and then connected between the source and the gate of the PMOS transistor Q1.
The utility model also provides a printer is equipped with foretell short-circuit protection circuit.
The utility model has the advantages of:
the utility model discloses can set up more accurate protection threshold current value, provide reliable current protection, and can avoid single or continuous pulse current to influence protection circuit, avoid the false triggering protection, reliability, security and stability are high, improve user experience, and circuit structure is simple, easily realizes.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a block diagram of a circuit structure according to an embodiment of the present invention;
fig. 2 is a circuit diagram of an embodiment of the present invention.
Detailed Description
To further illustrate the embodiments, the present invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. With these references, one of ordinary skill in the art will appreciate other possible embodiments and advantages of the present invention. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.
The present invention will now be further described with reference to the accompanying drawings and detailed description.
As shown in fig. 1 and 2, a short-circuit protection circuit 1 includes a current sampling circuit 13, a current spike removing circuit 11, a filter circuit 14, a comparison circuit 15, and a switch circuit 12, where the switch circuit 12 is connected in series in a loop to be protected, that is, the switch circuit 12 is connected between a power supply 2 and a load 3, the power supply 2 supplies power to the load 3 through the switch circuit 12, and the load 3 may be various electric devices such as a printer.
The current sampling circuit 13 is used for sampling the current of the loop to be protected, the output end of the current sampling circuit 13 is connected with the input end of the comparison circuit 15 through the current spike removing circuit 11 and the filter circuit 14 in sequence, and the output end of the comparison circuit 15 is connected with the control end of the switch circuit 12. Under normal conditions (namely, no short circuit occurs), the comparison circuit 15 drives the switch circuit 12 to be conducted, the load 3 works normally, and when a single pulse current (such as the moment of starting up a printer) occurs, the current spike removing circuit 11 can weaken the spike current, so that false triggering cannot occur; when continuous pulse current exists, the filter circuit can filter the influence, so that false triggering is avoided, and when a short circuit occurs, the comparison circuit 15 drives the switch circuit 12 to be disconnected to protect the load 3.
Preferably, in this embodiment, the current sampling circuit 13 includes a sampling resistor R1, the sampling resistor R1 is connected in series in the loop to be protected, and specifically, the sampling resistor R1 is connected in series between the input terminal VIN of the power supply 2 and the switching circuit 12. By using the current sampling circuit 13, the circuit structure is simple, the implementation is easy, and the cost is low, but not limited thereto, and in some embodiments, the current sampling circuit 13 may also be implemented by using other current sampling circuits in the prior art, which can be easily implemented by those skilled in the art and is not described in detail.
Preferably, in this embodiment, the current spike removing circuit 11 includes a capacitor C1, the capacitor C1 is connected in parallel with the sampling resistor R1, and the current spike removing circuit 11 has a simple circuit structure, is easy to implement, has a low cost, and has a small circuit volume, but is not limited thereto, and in other embodiments, the current spike removing circuit 11 may also be implemented by using other existing current spike removing circuits.
In this embodiment, the filter circuit 14 is preferably formed by a resistor and a capacitor, and has a simple structure, easy implementation, a good filtering effect, and a low cost, but not limited thereto.
Specifically, in this embodiment, the filter circuit 14 includes a resistor R3, a resistor R5, a capacitor C3, and a capacitor C4, the resistor R3 and the resistor R5 are connected in series and then connected between the end of the capacitor C1 connected to the switch circuit 12 (the output end of the current spike removal circuit 11) and the input end of the comparator circuit 15, two ends of the resistor R5 are grounded through the capacitor C3 and the capacitor C4, respectively, and the filter circuit 14 has a better filtering effect on the continuous pulse current, but is not limited thereto.
Preferably, in this embodiment, the comparison circuit 15 is implemented by using the comparator U1A, and has a simple structure, a small circuit size, and a low cost, but not limited thereto, and in some embodiments, the comparison circuit 15 may also be implemented by using other existing comparison circuits, such as a single chip.
Specifically, in this embodiment, the comparison circuit 15 includes a comparator U1A, a resistor R6, and a resistor R7, a positive input terminal of the comparator U1A is used as an input terminal of the comparison circuit 15, the resistor R6 and the resistor R7 are connected in series and then connected between the input terminal VIN of the power supply 2 and ground, a negative input terminal of the comparator U1A is used as a reference terminal and connected to a node between the resistor R6 and the resistor R7, a protection threshold current value can be adjusted by setting resistance values of the resistor R6 and the resistor R7, and an output terminal of the comparator U1A is connected to the control terminal of the switch circuit 12.
Preferably, in this embodiment, the switch circuit 12 includes a PMOS transistor Q1 and an NPN transistor Q2, the PMOS transistor Q1 is connected in series in the circuit to be protected, specifically, a source series resistor R1 of the PMOS transistor Q1 is connected to the input terminal VIN of the power supply 2, a drain of the PMOS transistor Q1 is connected to the input terminal VOUT of the load 3, a gate of the PMOS transistor Q1 is connected to the collector of the NPN transistor Q2, an emitter of the NPN transistor Q2 is connected to ground, and a base of the NPN transistor Q2 is connected to the output terminal of the comparator U1A (the output terminal of the comparison circuit 12). By using the switching circuit 12, the type selection of the comparator U1A is more flexible, the adaptability is better, and the implementation is easy, but not limited thereto, in some embodiments, the switching circuit 12 may also be implemented by using other existing switching circuits, such as a switching circuit implemented by using a single MOS transistor, which can be easily implemented by those skilled in the art and will not be described in detail.
Further, in this embodiment, the switch circuit 12 further includes a resistor R2 and a capacitor C2, and the resistor R2 and the capacitor C2 are connected in parallel and then connected between the source and the gate of the PMOS transistor Q1, so as to improve the driving stability and safety of the PMOS transistor Q1.
The working principle is as follows:
after the power supply 2 is input through the input end VIN, the power supply passes through the sampling resistor R1 to reach the source electrode of the PMOS transistor, when the current is below the short-circuit protection threshold current, the voltage of the positive input end of the comparator U1 is higher than that of the negative input end, the comparator U1 outputs high level, the NPN triode Q2 is conducted, the PMOS transistor Q1 is conducted, and the power supply is used for supplying power to the load 3 and starting up the load; when short circuit occurs (namely, the current is greater than the short-circuit protection threshold current), a large voltage difference is generated at two ends of the sampling resistor R1, the voltage of the positive input end of the comparator U1 is lower than the low level output by the voltage comparator U1 at the negative input end, the NPN triode Q2 is not conducted, the PMOS tube Q1 is closed, and the power supply 2 is switched to supply power to the load 3 continuously, so that the rear end is protected; when a current peak (such as a starting moment) comes, the peak voltage difference at the two ends of the sampling resistor R1 is weakened due to the existence of the capacitor C1, so that false triggering is prevented; when continuous pulse current exists, the filter circuit 14 consisting of the resistor R3, the resistor R5, the capacitor C3 and the capacitor C4 weakens the fluctuation to the minimum, and prevents false triggering.
The utility model also provides a printer is equipped with foretell short-circuit protection circuit 1.
The utility model discloses can set up more accurate protection threshold current value, provide reliable current protection, and can avoid single or continuous pulse current to influence protection circuit, avoid the false triggering protection, reliability, security and stability are high, improve user experience, and circuit structure is simple, easily realizes.
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A short-circuit protection circuit, characterized by: the protection circuit comprises a current sampling circuit, a current spike removing circuit, a filter circuit, a comparison circuit and a switch circuit, wherein the switch circuit is connected in series in a loop to be protected, the current sampling circuit is used for sampling the current of the loop to be protected, the output end of the current sampling circuit is connected with the input end of the comparison circuit sequentially through the current spike removing circuit and the filter circuit, and the output end of the comparison circuit is connected with the control end of the switch circuit.
2. The short-circuit protection circuit of claim 1, wherein: the current sampling circuit comprises a sampling resistor R1, and the sampling resistor R1 is connected in series in a loop to be protected.
3. The short-circuit protection circuit of claim 2, wherein: the current spike removal circuit comprises a capacitor C1, and a capacitor C1 is arranged in parallel with a sampling resistor R1.
4. The short-circuit protection circuit according to claim 1, 2 or 3, wherein: the filter circuit is composed of a resistor and a capacitor.
5. The short-circuit protection circuit of claim 4, wherein: the filter circuit comprises a resistor R3, a resistor R5, a capacitor C3 and a capacitor C4, wherein the resistor R3 and the resistor R5 are connected in series and then connected between the output end of the current spike removing circuit and the input end of the comparison circuit, and two ends of the resistor R5 are grounded through the capacitor C3 and the capacitor C4 respectively.
6. The short-circuit protection circuit of claim 1, wherein: the comparison circuit is implemented using comparator U1A.
7. The short-circuit protection circuit of claim 1, wherein: the switching circuit comprises a PMOS (P-channel metal oxide semiconductor) tube Q1 and an NPN (negative-positive-negative) triode Q2, the PMOS tube Q1 is connected in the loop to be protected in series, the grid electrode of the PMOS tube Q1 is connected with the collector electrode of the NPN triode Q2, the emitting electrode of the NPN triode Q2 is grounded, and the base electrode of the NPN triode Q2 is connected with the output end of the comparison circuit.
8. The short-circuit protection circuit of claim 7, wherein: the switch circuit further comprises a resistor R2 and a capacitor C2, wherein the resistor R2 and the capacitor C2 are connected in parallel and then connected between the source and the gate of the PMOS transistor Q1.
9. A printer, characterized by: a short-circuit protection circuit as claimed in any one of claims 1 to 8 is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120308650.8U CN214543597U (en) | 2021-02-03 | 2021-02-03 | Short-circuit protection circuit and printer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120308650.8U CN214543597U (en) | 2021-02-03 | 2021-02-03 | Short-circuit protection circuit and printer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214543597U true CN214543597U (en) | 2021-10-29 |
Family
ID=78233339
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120308650.8U Active CN214543597U (en) | 2021-02-03 | 2021-02-03 | Short-circuit protection circuit and printer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN214543597U (en) |
-
2021
- 2021-02-03 CN CN202120308650.8U patent/CN214543597U/en active Active
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CP03 | Change of name, title or address | ||
| CP03 | Change of name, title or address |
Address after: 361000 305A room, Aung Yip house, Pioneer Park, torch high tech Zone, Xiamen, Fujian Patentee after: Xiamen Hanyin Co.,Ltd. Country or region after: China Address before: 361000 305A room, Aung Yip house, Pioneer Park, torch high tech Zone, Xiamen, Fujian Patentee before: XIAMEN HANIN ELECTRONIC TECHNOLOGY Co.,Ltd. Country or region before: China |