A short-circuit detection circuit, a short-circuit protection circuit and a switching power supply circuit

Abstract

The present invention discloses a short-circuit detection circuit, a short-circuit protection circuit and a switching power supply circuit. The short-circuit detection circuit includes: a sampling circuit connected to a communication line; the sampling circuit is used to collect the operating voltage of the communication line; a voltage follower, the input end of the voltage follower is connected to the sampling circuit, and the output end of the voltage follower is connected to the input end of a controller; the controller is used to judge whether the communication line is short-circuited according to the voltage output by the voltage follower; a voltage stabilizing circuit, one end of the voltage stabilizing circuit is connected to the output end of the voltage follower; the voltage stabilizing circuit has a charging and discharging operating state. With such a setting, when the communication line is working normally and the voltage fluctuates, the voltage stabilizing circuit can enable the voltage obtained at the input end of the controller to be maintained at a relatively high value, thereby meeting the conditions for triggering short-circuit protection and improving the reliability of the short-circuit detection circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and particularly relates to a short - circuit detection circuit, a short - circuit protection circuit and a switching power supply circuit. Background Art

[0002] In the prior art, the communication voltage on the communication line is output by a switching power supply. When the communication line is short - circuited, the load power on the communication line increases instantaneously. Due to the feedback circuit, the switching power supply adjusts the duty cycle to increase the output voltage. Since the total energy remains unchanged and the load power suddenly increases, the output of the feedback circuit will be pulled down a little. When the feedback circuit adjusts to stability and the short - circuit state still exists, it will lead to repeated adjustment. Therefore, the switching power supply cannot provide enough energy to maintain voltage stability instantaneously.

[0003] In this case, the voltage of the switching power supply may fluctuate, resulting in a small detected short - circuit voltage detection value, so that it is impossible to determine whether there is a short - circuit. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is the problem that the detected short - circuit voltage detection value in the prior art is small, so that it is impossible to determine whether there is a short - circuit, and thus a short - circuit detection circuit, a short - circuit protection circuit and a switching power supply circuit are provided.

[0005] To achieve the above object, an embodiment of the present invention provides a short - circuit detection circuit, which includes: a sampling circuit connected to the communication line; the sampling circuit is used to collect the working voltage of the communication line; a voltage follower, the input end of the voltage follower is connected to the sampling circuit, and the output end of the voltage follower is connected to the input end of the controller; the controller is used to judge whether the communication line is short - circuited according to the voltage output by the voltage follower; a voltage - stabilizing circuit, one end of the voltage - stabilizing circuit is connected to the output end of the voltage follower; the voltage - stabilizing circuit has charging and discharging working states.

[0006] Optionally, the voltage - stabilizing circuit is a charging capacitor.

[0007] Optionally, the capacitance of the charging capacitor is between 20 uF and 25 uF.

[0008] Optionally, a load resistor is arranged on the communication line.

[0009] Optionally, the sampling circuit includes: a sampling resistor, one end of the sampling resistor is connected to the load resistor, and the other end of the sampling resistor is grounded.

[0010] Optionally, the sampling resistor is composed of multiple voltage - dividing resistors connected in parallel.

[0011] Optionally, the sampling circuit further includes: an input resistor, one end of the input resistor is connected to the load resistor, and the other end of the input resistor is connected to the input end of the voltage follower.

[0012] Optionally, the sampling circuit further includes: a filter circuit, one end of the filter circuit is connected to the input end of the voltage follower, and the other end of the filter circuit is grounded.

[0013] An embodiment of the present invention further provides a short-circuit protection circuit, which includes: a switch circuit and the short-circuit detection circuit as described in any one of the above embodiments, the controller is connected to the switch circuit, and the controller is adapted to control the on / off of the communication line through the switch circuit.

[0014] An embodiment of the present invention further provides a switching power supply circuit, which includes: the short-circuit detection circuit as described in any one of the above embodiments, or the short-circuit protection circuit as described in the above embodiments.

[0015] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0016] 1. An embodiment of the present invention provides a short-circuit detection circuit, which includes: a sampling circuit connected to a communication line; the sampling circuit is used to collect the operating voltage of the communication line; a voltage follower, the input end of the voltage follower is connected to the sampling circuit, and the output end of the voltage follower is connected to the input end of the controller; the controller is used to judge whether the communication line is short-circuited according to the voltage output by the voltage follower; a voltage stabilizing circuit, one end of the voltage stabilizing circuit is connected to the output end of the voltage follower; the voltage stabilizing circuit has a charging and discharging working state.

[0017] With such a setting, since the voltage follower is a deep voltage series negative feedback circuit, it has the characteristics of high operation accuracy, large input resistance, and small output resistance, thus improving the detection accuracy of the short-circuit detection circuit. And, in this embodiment, the operating voltage collected by the sampling circuit charges the voltage stabilizing circuit through the voltage follower, so that when the communication line is working normally and the voltage fluctuates, the voltage stabilizing circuit can make the voltage obtained at the input end of the controller maintain a relatively high value, thus meeting the conditions for triggering short-circuit protection and improving the reliability of the short-circuit detection circuit. Description of the Drawings

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a schematic diagram of the overall structure of the short - circuit detection circuit according to the embodiment of the present invention.

[0020] Reference numerals:

[0021] 10. Voltage follower; 20. Sampling circuit; 30. Controller;

[0022] R1. Load resistor; R2. First voltage - dividing resistor; R3. Input resistor; R4. Second voltage - dividing resistor; R5. Third voltage - dividing resistor; C1. Charging capacitor; C2. Filtering capacitor. Specific embodiments

[0023] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the drawings. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0024] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0025] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can also be the internal connection of two components. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0026] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] In the prior art, the communication voltage on the communication line is output by a switching power supply. When the communication line is short-circuited, the load power on the communication line increases instantaneously. Due to the feedback circuit, the switching power supply adjusts the duty cycle to increase the output voltage. Since the total energy remains unchanged and the load power suddenly increases, the output of the feedback circuit will be pulled down a little. When the feedback circuit is adjusted to be stable and the short-circuit state still exists, repeated adjustment will occur. Therefore, the switching power supply cannot provide enough energy instantaneously to maintain the voltage stability. In this case, the voltage of the switching power supply may fluctuate, resulting in a too small detected short-circuit voltage detection value, so that it is impossible to determine whether there is a short circuit.

[0028] Therefore, the technical problem to be solved by the present invention is the problem that the detected short-circuit voltage detection value in the prior art is too small, so that it is impossible to determine whether there is a short circuit, and thus a short-circuit detection circuit, a short-circuit protection circuit and a switching power supply circuit are provided.

[0029] Embodiment 1

[0030] As Figure 1 shown, the embodiment of the present invention provides a short-circuit detection circuit, which includes: a controller 30, a sampling circuit 20, a voltage follower 10 and a voltage stabilizing circuit.

[0031] Specifically, in the embodiment of the present invention, as Figure 1 shown, between A and B is the communication line. The first end of the sampling circuit 20 is connected to the communication line, and the sampling circuit 20 is used to collect the working voltage of the communication line. The input end of the voltage follower 10 is connected to the second end of the sampling circuit 20. In the embodiment of the present invention, the output end of the voltage follower 10 is connected to the input end of the controller 30, and the controller 30 is used to judge whether the communication line is short-circuited according to the voltage output by the voltage follower 10. The voltage follower 10 is composed of an operational amplifier. The non-inverting input end of the operational amplifier is connected to the second end of the sampling circuit 20, the inverting input end of the operational amplifier is connected to the output end of the operational amplifier, and the output end of the operational amplifier is connected to the input end of the controller 30. When the communication line is short-circuited, the current flowing through the communication line increases, so that the current in the sampling circuit 20 also increases synchronously, and thus the sampling voltage increases. After the voltage value detected by the controller 30 exceeds the preset voltage value, it can be judged that the communication line is short-circuited. One end of the voltage stabilizing circuit is connected to the output end of the voltage follower 10; the voltage stabilizing circuit has a charging and discharging working state.

[0032] With such a setting, since the voltage follower 10 is a deep voltage series negative feedback circuit, it has the characteristics of high operation accuracy, large input resistance R3, and small output resistance, thus improving the detection accuracy of the short-circuit detection circuit.

[0033] In this embodiment, the controller 30 can determine whether it is in a short-circuit state by judging that the sampled voltage value for a continuous preset time period is greater than the preset voltage value. For example, the preset time period can be 10 ms, and the preset voltage value can be 0.7 V. When in a short-circuit state, the controller 30 can cut off the power supply to protect the communication circuit. After a period of time, such as 5 s later, the power supply is restarted, and the voltage is synchronously detected. If it is no longer in a short-circuit state, normal power supply and communication start; if it is still in a short-circuit state, it continues to be disconnected and is restarted again after 5 s. In this embodiment, by setting the voltage stabilizing circuit, the working voltage collected by the sampling circuit 20 is charged to the voltage stabilizing circuit through the voltage follower 10, so that the voltage obtained by the input end of the controller 30 can be maintained at a relatively high value by the voltage stabilizing circuit during normal operation and voltage fluctuation of the communication line, preventing the situation that the controller 30 cannot collect a high voltage value for a sufficient duration due to the short duration of voltage fluctuation, resulting in non-disconnection of the power supply, thus meeting the conditions for triggering short-circuit protection and improving the reliability of the short-circuit detection circuit.

[0034] Optionally, in an embodiment of the present invention, the voltage stabilizing circuit may be a charging capacitor C1. Of course, this embodiment is only an example of the type of the voltage stabilizing circuit, but it is not limited. Those skilled in the art can change the type of the voltage stabilizing circuit according to the actual situation as long as the same technical effects can be achieved.

[0035] Further, in an optional embodiment of the embodiment of the present invention, the capacitance of the charging capacitor C1 is between 20 uF and 25 uF. For example, the capacitance of the charging capacitor C1 can be 22 uF. Of course, this embodiment is also an example of the capacitance of the charging capacitor C1, but it is not limited. Those skilled in the art can change the capacitance of the charging capacitor C1 according to the actual situation as long as the same technical effects can be achieved.

[0036] In an alternative embodiment of the embodiment of the present invention, a load resistor R1 is provided on the communication line. The sampling circuit 20 includes a sampling resistor, one end of the sampling resistor is connected to the load resistor R1, and the other end of the sampling resistor is grounded. Specifically, the sampling resistor may be composed of a plurality of voltage-dividing resistors connected in parallel. For example, the plurality of voltage-dividing resistors may be a first voltage-dividing resistor R2, a second voltage-dividing resistor R4, and a third voltage-dividing resistor R5 respectively, and the resistance values of the first voltage-dividing resistor R2, the second voltage-dividing resistor R4, and the third voltage-dividing resistor R5 may be the same or different. The resistance values of the first voltage-dividing resistor R2, the second voltage-dividing resistor R4, and the third voltage-dividing resistor R5 may all be 3.9 KΩ. This embodiment also gives an example of the magnitude of the resistance value, but it is not limited thereto. Those skilled in the art can change the magnitude of the resistance value according to the actual situation as long as the same technical effect can be achieved.

[0037] Further, in an alternative embodiment of the embodiment of the present invention, the sampling circuit 20 further includes an input resistor R3. One end of the input resistor R3 is connected to the load resistor R1, and the other end of the input resistor R3 is connected to the input end of the voltage follower 10. The resistance value of the input resistor R3 may be 1 KΩ. This embodiment also gives an example of the magnitude of the resistance value, but it is not limited thereto. Those skilled in the art can change the magnitude of the resistance value according to the actual situation as long as the same technical effect can be achieved.

[0038] Optionally, the sampling circuit 20 further includes a filtering circuit. One end of the filtering circuit is connected to the input end of the voltage follower 10, and the other end of the filtering circuit is grounded. In the embodiment of the present invention, the filtering circuit may be a filtering capacitor C2, and the capacitance of the filtering capacitor C2 may be 100 nF. This embodiment also gives an example of the capacitance of the filtering capacitor C2, but it is not limited thereto. Those skilled in the art can change the capacitance of the filtering capacitor C2 according to the actual situation as long as the same technical effect can be achieved.

[0039] The embodiment of the present invention further provides a short-circuit protection circuit, which includes: a switch circuit and the short-circuit detection circuit as described in any of the above embodiments. The controller 30 is connected to the switch circuit, and the controller 30 is adapted to control the on / off of the communication line through the switch circuit. In the actual detection process, the following detection method can be used for detection:

[0040] The controller 30 can perform intermittent sampling through the sampling circuit 20, for example, sampling once every 1 ms. When the sampled voltage value is greater than the preset voltage value and the number of times it is greater is 7 times, it is determined that the communication line is in a short-circuit state. The preset voltage value can be 0.7V. When the communication line is in a short-circuit state, the controller 30 cuts off the power supply through the switch circuit to protect the communication circuit. After a period of time, such as 5 s later, the power supply is restarted, and the voltage is detected by synchronous multiple samplings. If it is no longer in a short-circuit state, normal power supply and communication start.

[0041] The embodiment of the present invention further provides a switching power supply circuit, which includes: the short-circuit detection circuit described in any of the above embodiments, or, the short-circuit protection circuit described in the above embodiments.

[0042] Obviously, the above embodiments are merely examples given for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A short-circuit detection circuit, characterized in that, Comprising: A sampling circuit (20), connected to the communication line; The sampling circuit (20) is used to collect the operating voltage of the communication line; A voltage follower (10), the input end of the voltage follower (10) is connected to the sampling circuit (20), and the output end of the voltage follower (10) is connected to the input end of the controller (30); the controller (30) is used to judge whether the communication line is short-circuited according to the voltage output by the voltage follower (10); A voltage stabilizing circuit, one end of the voltage stabilizing circuit is connected to the output end of the voltage follower (10); the voltage stabilizing circuit has charging and discharging operating states; the operating voltage collected by the sampling circuit (20) charges the voltage stabilizing circuit through the voltage follower (10), so that when the communication line is working normally and the voltage fluctuates, the voltage obtained by the input end of the controller (30) is maintained at a certain value by the voltage stabilizing circuit.

2. The short-circuit detection circuit according to claim 1, wherein The voltage stabilizing circuit is a charging capacitor (C1).

3. The short-circuit detection circuit according to claim 2, wherein The capacitance of the charging capacitor (C1) is between 20uF and 25uF.

4. The short-circuit detection circuit according to any one of claims 1 to 3, characterized in that A load resistor (R1) is arranged on the communication line.

5. The short-circuit detection circuit according to claim 4, wherein The sampling circuit (20) comprises: A sampling resistor, one end of the sampling resistor is connected to the load resistor (R1), and the other end of the sampling resistor is grounded.

6. The short-circuit detection circuit according to claim 5, wherein The sampling resistor is composed of a plurality of voltage-dividing resistors connected in parallel.

7. The short-circuit detection circuit according to claim 6, wherein The sampling circuit (20) further comprises: An input resistor (R3), one end of the input resistor (R3) is connected to the load resistor (R1), and the other end of the input resistor (R3) is connected to the input end of the voltage follower (10).

8. The short-circuit detection circuit according to claim 6, wherein The sampling circuit (20) further comprises: A filtering circuit, one end of the filtering circuit is connected to the input end of the voltage follower (10), and the other end of the filtering circuit is grounded.

9. A short - circuit protection circuit, characterized in that, Comprising: A switch circuit and the short-circuit detection circuit according to any one of claims 1 to 8, the controller (30) is connected to the switch circuit, and the controller (30) is adapted to control the on-off of the communication line through the switch circuit.

10. A switching power supply circuit, characterized in that, Comprising: The short-circuit detection circuit according to any one of claims 1 to 8, or the short-circuit protection circuit according to claim 9.

Images