Power supply protection circuit

Abstract

A power supply protection circuit is at least provided with a current switch unit and a short circuit protection unit, when a first switch and a second switch of the current switch unit are started, voltage input by a first input power supply end can be output to a load from an output power supply end, and a third switch is kept in a closed state; and when the output power supply end is short-circuited, the third switch and the fourth switch are started, the first switch and the second switch are turned off, and the voltage input by the first input power supply end cannot be output to the load from the output power supply end. According to the protection circuit of the utility model, before fault elimination, bolt locking is carried out, and the bolt locking state is released only when short circuit investigation is carried out by a technician, so that the normal operation state is recovered.

Description

Technical Field

[0001] This utility model relates to a power supply protection circuit, and more particularly to a power supply protection circuit that can protect the output circuit when it is short-circuited. Background Technology

[0002] Electronic products are ubiquitous in our lives, and most of them have external connectors as interfaces for circuit input and output. Short circuits can easily occur due to carelessness during connection, which may lead to safety issues. This is something we need to be seriously concerned about.

[0003] For example, electrical fire is one of the most common safety problems. It can occur when a customer uses excessive current or experiences a short circuit. Short circuit protection circuits typically use fuses or integrated circuits (ICs) for short circuit protection. If a fuse is not used, other methods such as... Figure 1 The circuit shown has the following characteristics:

[0004] (1) The key point of this circuit design is that the time constant of C2 and R1 needs to be much smaller than that of C1 and R3. Therefore, R3 needs to have a larger resistance value to meet the circuit requirements.

[0005] (2) When the load of Vout is normal, Q2 will be started first because the time constants of C2 and R1 are less than those of C1 and R3. When Q2 is started, Vout is at a high potential, which drives the base of Q1 to a high potential, so that Q1 is not started.

[0006] (3) When Vout is short-circuited, it drives the base of Q1 to a low potential, causing Q1 to start. After Q1 starts, it causes the base of Q2 to a high potential, causing Q2 to turn off. At this time, the load can be replaced and the circuit can be restarted.

[0007] In addition, if a fuse is used for short circuit protection, it may cause the electronic product to burn out before the fuse burns out when protecting more delicate electronic products (the fuse's response speed is too slow). Therefore, when the fuse fails, it needs to be replaced. In addition, the circuit board using the fuse also needs to be replaced and other surrounding circuits need to be checked.

[0008] In addition, another option is to use IC-based designs for protection, but this is more expensive and not easy to repair once a fault occurs.

[0009] The above-mentioned protection methods may not have a locking function. Therefore, once a load short circuit occurs, the protection circuit will be activated to shut off the power switch. After shutting off, the power switch will be turned on again because it is impossible to detect whether the load short circuit has been truly eliminated. This creates a cycle of on-off protection, which eventually burns out the switch of the short circuit protection circuit. Utility Model Content

[0010] To address the aforementioned drawbacks, this invention requires a locking mechanism to be generated after a short circuit occurs, and the locking mechanism should only be released after the cause of the short circuit has been completely eliminated, thus achieving true protection. Therefore, this invention designs a protection circuit with a locking function, which meets the requirements for short circuit protection while reducing costs and maintenance difficulty, and ensures that the circuit can only be unlocked after the fault has been eliminated. Therefore, this invention is a superior solution.

[0011] To achieve the above objectives, the present invention provides a power supply protection circuit comprising: a current switching unit electrically connected to a first input power supply terminal and an output power supply terminal, the current switching unit having a first switch and a second switch, wherein when the first switch and the second switch of the current switching unit are activated, the voltage input to the first input power supply terminal is output to a load from the output power supply terminal; a short-circuit protection unit electrically connected to the current switching unit and the output power supply terminal, the short-circuit protection unit having a third switch and a fourth switch, wherein when the voltage input to the first input power supply terminal is output to the load from the output power supply terminal, the third switch remains closed; and wherein, when the output power supply terminal is short-circuited, the third switch and the fourth switch are activated, and the first switch and the second switch are simultaneously closed, preventing the voltage input to the first input power supply terminal from being output to the load from the output power supply terminal.

[0012] More specifically, the short-circuit protection unit further includes a first voltage divider component. When the voltage input at the first input power terminal is output to the load from the output power terminal, the first voltage divider component can output a first voltage divider value to keep the third switch in the closed state.

[0013] More specifically, the short-circuit protection unit further includes a second voltage divider component. After the third switch is activated, the second voltage divider component can output a second voltage divider value to the fourth switch to activate the fourth switch.

[0014] More specifically, the short-circuit protection unit also includes a second input power terminal. If a high potential voltage is input to the second input power terminal, the first switch will be activated before the third switch. Activation of the first switch will activate the second switch, allowing the voltage input to the first input power terminal to be output to the load from the output power terminal.

[0015] More specifically, if a high potential voltage is continuously input to the second input power terminal after a short circuit occurs at the output power terminal, the third switch will remain in the activated state to prevent the voltage input to the first input power terminal from being output to the load from the output power terminal.

[0016] More specifically, if a low potential voltage is input to the second input power terminal, the first switch, the second switch, the third switch, and the fourth switch will all be turned off. Attached Figure Description

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] Figure 1 This is a circuit diagram of an existing short-circuit protector.

[0019] Figure 2 This is a schematic diagram of the power protection circuit architecture of this utility model.

[0020] Figure 3 This is a circuit diagram of the power protection circuit of this utility model.

[0021] Figure 4A This is a schematic diagram of the controller startup and relative points of the power protection circuit of this utility model.

[0022] Figure 4B This is a schematic diagram of the controller startup time of the power protection circuit of this utility model.

[0023] Figure 5A This is a schematic diagram of the waveforms at various points when the short-circuit protection of the power supply protection circuit of this utility model is activated.

[0024] Figure 5B This is a schematic diagram showing the time required for the short-circuit protection circuit of this utility model to start and output.

[0025] Figure 6 This is a schematic diagram showing the time required for the short-circuit protection of the power supply protection circuit of this utility model to start and the switch to close.

[0026] Figure 7 This is a schematic diagram showing the unlocking waveform and required time for the power protection circuit of this utility model.

[0027] Explanation of reference numerals in the attached figures

[0028] 1: Power protection circuit

[0029] 11: Current Switching Unit

[0030] 12: Short circuit protection unit

[0031] 13: First input power terminal

[0032] 14: Output power terminal

[0033] 15: Second input power terminal

[0034] 2: Controller

[0035] 3: Load. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Many specific details are set forth in the following description to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0037] Please see Figure 2 and Figure 3 The figure shows a schematic diagram of the power protection circuit of this utility model. As shown in the figure, the environment or device in which the power protection circuit 1 is applied is a circuit board or an electronic device with a circuit board inside.

[0038] like Figure 2 As shown, the power protection circuit 1 has a current switch unit 11, a short circuit protection unit 12, a first input power terminal 13, an output power terminal 14 and a second input power terminal 15.

[0039] The current switching unit 11 is electrically connected to the first input power supply terminal 13 and the output power supply terminal 14. The current switching unit 11 has a first switch (to... Figure 3 From the circuit perspective, Q8 is the first switch) and a second switch (with Figure 3 From the circuit perspective, Q2 is the second switch. When the first switch and the second switch of the current switching unit 11 are activated, the voltage input to the first input power supply terminal 13 can be output to a load 3 from the output power supply terminal 14.

[0040] The short-circuit protection unit 12 is electrically connected to the current switching unit 11 and the output power supply terminal 14. The short-circuit protection unit 12 has a third switch (to... Figure 3 From the circuit perspective, Q7 is the third switch) and a fourth switch (with Figure 3 From the circuit perspective, Q10 is the fourth switch. When the voltage input at the first input power terminal 13 is output to the load from the output power terminal 14, the third switch remains closed.

[0041] The second input power terminal 15 is connected to a controller 2, which can be a microprocessor or a low-potential voltage.

[0042] When a high potential voltage is input to the second input power terminal 15, the first switch will be activated before the third switch. The activation of the first switch will enable the second switch to be activated, and the voltage input to the first input power terminal can be output to the load 3 from the output power terminal.

[0043] If a problem occurs with load 3, or any other circuit problem, causing a short circuit at the output power terminal 14, the third and fourth switches will be activated, while the first and second switches will be deactivated, preventing the voltage input at the first input power terminal 13 from being output to the load 3 from the output power terminal 14.

[0044] Meanwhile, when the output power terminal 14 is short-circuited, if the second input power terminal 15 continues to input the high potential voltage, the third switch will remain in the activated state to prevent the voltage input from the first input power terminal from being output to the load from the output power terminal; conversely, if the second input power terminal 15 inputs a low potential voltage, the first switch, the second switch, the third switch and the fourth switch will all be turned off.

[0045] Therefore, circuit maintenance personnel can use the circuit's locking mechanism to prevent repeated switching of the circuit from damaging the switching components before troubleshooting a short circuit. Once the short circuit has been eliminated, the controller 2 can send a low-potential voltage signal to close the first, second, third, and fourth switches, and then send a high-potential voltage signal to activate the first and second switches, so that the circuit can resume normal operation.

[0046] like Figure 3 The diagram shows the implementation circuit architecture of this power protection circuit. The normal operating mechanism of the circuit is explained below:

[0047] (1) When the controller sends a high potential voltage (12_EN) to the second input power terminal 15, the current will directly turn on the first switch (Q8) through R59. When the first switch (Q8) is turned on, the second switch (Q2) will also be turned on, so that the voltage (12V) input to the first input power terminal 13 can be output to the load from the output power terminal 14 (12_VIB).

[0048] (2) Although the current will flow through R15 and C15 and charge C15 so that the potential of the third switch (Q7) will gradually rise, the speed at which the potential rises cannot be faster than the speed at which the second switch (Q2) turns on. Therefore, when the second switch (Q2) is turned on, the first voltage divider (VR55) output by the first voltage divider component (R54, R55) will be higher than the VBE of the third switch (Q7) because of the resistance setting of R55. Therefore, the third switch (Q7) cannot be turned on, and the fourth switch (Q10) also cannot be turned on. This can meet the normal circuit operation requirements.

[0049] like Figure 3 As shown, the short-circuit operation mechanism of its circuit is explained as follows:

[0050] (1) If the output power terminal 14 (12_VIB) is short-circuited, causing the voltage to drop to 0V, in this state, the VBE of the third switch (Q7) will be higher than VBC, so the third switch will be turned on. At this time, the high potential voltage (12_EN) will be continuously sent to the second input power terminal 15. Therefore, whether it is the high potential voltage (12_EN) or the voltage discharged by C15, after being divided by the second voltage divider component (R15, R57), the second voltage divider voltage value (VR57) is given to the fourth switch (Q10) to enable the fourth switch (Q10).

[0051] (2) When the fourth switch (Q10) is activated, the gate potential of the first switch (Q8) will be pulled down instantly, which will cause the first switch (Q8) to close. At the same time, the second switch (Q2) will also close. Therefore, the voltage input to the first input power supply terminal 13 cannot be output to the load from the output power supply terminal 14.

[0052] (3) If the load is only briefly short-circuited (e.g., accidentally touched), and if the second switch (Q2) does not have time to close, the output power terminal 14 (12_VIB) will suddenly return to normal. In order to avoid repeated switching, the circuit of this utility model will have R55 and R58 connected in parallel after the fourth switch (Q10) is turned on. If the output power terminal 14 (12_VIB) suddenly returns to normal, it will be divided by the third voltage divider component (R54, R55 in parallel with R58) to produce a third voltage divider value (VR55 in parallel with R58). However, the third voltage divider value will be too small and will be lower than the VBE of the third switch (Q7). Therefore, it is not enough to close the third switch (Q7). This allows the third switch (Q7) to remain open. At the same time, when the second switch (Q2) is closed, the power state of the output power terminal 14 (12_VIB) will not affect the operation of the entire circuit.

[0053] (4) Since the high potential voltage (12_EN) will be continuously sent to the second input power supply terminal 15, the controller can know that the latching function has been triggered by SCP_DET=”1”; therefore, the relevant circuit management personnel can also perform maintenance and inspection.

[0054] (5) Once the cause of the short circuit is confirmed and eliminated, the controller 2 can send a low potential voltage signal to the second input power terminal 15 to close the first switch, the second switch, the third switch and the fourth switch. The controller can know that the locking function has been released by SCP_DET=”0”.

[0055] (6) The controller can send out a high potential voltage signal to start the first switch and the second switch so that the circuit can resume normal operation.

[0056] The following explanation uses four signal points (C1, C2, C3, C4) in the circuit to illustrate the relevant changes in circuit operation.

[0057] like Figure 4A As shown, when controller 2 sends out the 12_EN start signal (C2), it will simultaneously make OCP_EN (C4) high, and finally make the second switch (Q2) officially open to send out 12V_VIB (C1). During this period, SCP_DET (C3) remains at a low level, indicating that no short circuit has occurred.

[0058] like Figure 4B As shown, the time between the input of the high potential voltage (12_EN) and the formal opening of the second switch (Q2) to 12V_VIB (C1) is 2.75ms.

[0059] like Figure 5A As shown, when a short circuit occurs in 12V_VIB (C1), SCP_DET (C3) becomes high and informs the controller that a short circuit has occurred. At this time, the 12_EN (C2) signal previously sent by the controller remains high so that the short circuit can be locked.

[0060] Before a short circuit occurs in the power supply, the gate voltage (C4) of the second switch (Q2) is lower than the source voltage of the second switch (Q2), which enables the second switch (Q2) to start. Once a short circuit occurs, the gate voltage (C4) of the second switch (Q2) will rise to the same level as the source voltage of the second switch (Q2), thus turning off the second switch (Q2).

[0061] like Figure 5B As shown, the time required for the voltage of SCP_DET (C3) to rise to 3.5V (the voltage at which the controller's GPIO becomes "1") when a short circuit occurs in 12V_VIB (C1) is 4.08µs.

[0062] like Figure 6 As shown, when a short circuit occurs in 12V_VIB (C1), the voltage at the gate (C4) of the second switch (Q2) is pulled to its lowest point due to the short circuit. After the second switch (Q2) is closed, the voltage at the gate (C4) of the second switch (Q2) begins to rise. The point from the occurrence of the short circuit to this voltage rise (when the second switch is closed) is the actual short circuit protection activation time (3.2us).

[0063] like Figure 7 As shown, when 12V_VIB (C1) is briefly short-circuited and then reopened, 12V_EN (C2) passes through the third switch (Q7), which allows the base of the third switch (Q7) to have a conducting voltage, thus causing the 12V_VIB output to have a level of approximately 4.3V.

[0064] When 12V_EN (C2) changes from Hi to Low, the voltage of SCP_DET (C3) will also gradually decrease. When it decreases to less than 2V, the controller's GPIO will recognize it as Low level. Therefore, the time from 12V_EN to SCP_DET being below 2V is the time to release the latch (2.44ms).

[0065] The power protection circuit provided by this utility model has the following advantages compared with other existing technologies:

[0066] (1) This utility model provides a power protection circuit, which is a protection circuit with a latching function. It achieves the short circuit protection requirement while reducing cost and maintenance difficulty, and ensures that the circuit can be unlocked only after the fault is cleared.

[0067] (2) The present invention relates to a short circuit protection circuit that does not require a fuse and can be controlled by an MCU to start or stop. When the output circuit is short-circuited, the circuit can be quickly shut down and has a latching function. The protection circuit can be restarted only after the short circuit fault has been completely eliminated, thus avoiding system overheating or line damage.

[0068] The present invention has been disclosed above through the above embodiments, but it is not intended to limit the present invention. Any person skilled in the art, after understanding the foregoing technical features and embodiments of the present invention, may make some modifications and refinements without departing from the protection scope of the present invention.

Claims

1. A power supply protection circuit, characterized by, The application relates to a short-circuit protection unit, which comprises: a current switch unit electrically connected with a first input power terminal and an output power terminal, the current switch unit having a first switch and a second switch, when the first switch and the second switch of the current switch unit are activated, the voltage inputted by the first input power terminal can be outputted from the output power terminal to a load; a short-circuit protection unit electrically connected with the current switch unit and the output power terminal, the short-circuit protection unit having a third switch and a fourth switch, when the voltage inputted by the first input power terminal is outputted from the output power terminal to the load, the third switch is kept in a closed state; and when the output power terminal is short-circuited, the third switch and the fourth switch are activated, the first switch and the second switch are closed, and the voltage inputted by the first input power terminal cannot be outputted from the output power terminal to the load.

2. The power supply protection circuit of claim 1, wherein, The short-circuit protection unit further comprises a first voltage dividing component, when the voltage inputted by the first input power terminal is outputted from the output power terminal to the load, the first voltage dividing component can output a first voltage dividing value for keeping the third switch in the closed state.

3. The power supply protection circuit of claim 1, wherein, The short-circuit protection unit further comprises a second voltage dividing component, after the third switch is activated, the second voltage dividing component can output a second voltage dividing value to the fourth switch for activating the fourth switch.

4. The power supply protection circuit of claim 1, wherein, The short-circuit protection unit further comprises a second input power terminal, if the second input power terminal inputs a high voltage, the first switch is activated prior to the third switch, and when the first switch is activated, the second switch is activated, and the voltage inputted by the first input power terminal can be outputted from the output power terminal to the load.

5. The power supply protection circuit of claim 4, wherein, After the output power terminal is short-circuited, if the second input power terminal continuously inputs the high voltage, the third switch is kept in the activated state, so that the voltage inputted by the first input power terminal cannot be outputted from the output power terminal to the load.

6. The power supply protection circuit of claim 4, wherein, If the second input power terminal inputs a low voltage, the first switch, the second switch, the third switch and the fourth switch are all closed.

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