Short-circuit protection detection circuit
Through a short-circuit protection detection circuit combining photocoupler and small resistance value resistor, the continuous short-circuit heating problem caused by cement resistance is solved, delay reset is achieved, transistors are protected, and heat generation is reduced.
Patent Information
- Application Number
- CN202422467186.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-12
- Publication Date
- 2025-08-12
- Estimated Expiration
- 2034-10-12
AI Technical Summary
In the existing short-circuit protection detection circuit, cement resistors with a large resistance value are used for short-circuit detection, which leads to continuous accumulation of heat, which may cause the MOS tube to overheat and burn.
The photocoupler and a small resistance value resistor are used to charge the capacitor when the photocoupler is turned on, and the transistor delay control is combined to form a delay effect of fast charging and slow release, avoid continuous short circuit triggering, and protect the transistor.
Delay reset is achieved, avoiding continuous short circuit of cement resistors to generate heat, protecting the transistors, and reducing the heat generation.
Smart Images
Figure CN223218822U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of integrated circuits, and particularly relates to a short-circuit protection detection circuit. Background Art
[0002] In industrial automation and electronic equipment, 24V system power supplies are widely used in a variety of devices and equipment. Due to their high voltage levels, a short circuit can cause serious damage to the power system, load equipment, and operators. Therefore, ensuring short-circuit protection in power systems is crucial.
[0003] In the existing short-circuit protection detection circuit, a cement resistor with a relatively large resistance is used to divide the voltage through the heat generated by the cement resistor. The voltage signal after the voltage division is monitored to determine whether a short circuit has occurred. Because a cement resistor with a relatively large resistance is used for short-circuit detection, continuous short circuits within 1 second cause continuous heat accumulation. If the time is too long, the MOS tube used to trigger the short-circuit protection will overheat and eventually burn out. Utility Model Content
[0004] In order to overcome the deficiencies of the existing technical solutions, the present invention provides a short-circuit protection detection circuit that can effectively solve the problems raised by the background technology.
[0005] According to the first aspect of the present utility model, the device includes a first power input terminal, a second power input terminal, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a first transistor, a second transistor, a first capacitor, a second capacitor, a third capacitor, and a photocoupler. The first power input terminal is connected to the first resistor and then to the collector of the first transistor. The base of the first transistor is electrically connected to one end of the first capacitor and the second resistor. The other end of the second resistor is respectively connected to one end of the third resistor, the fourth resistor, and the fifth resistor. One end of the fourth resistor is also connected to the ground. The other ends of the third resistor and the fourth resistor are grounded. The fifth The other end of the resistor is connected to the second capacitor and then grounded. The other end of the fifth resistor is also connected to the first input pin of the photoelectric coupler, the second input pin of the photoelectric coupler is grounded, the third output pin of the photoelectric coupler is connected to the second power supply input, the fourth output pin of the photoelectric coupler is connected to one end of the sixth resistor, the other end of the sixth resistor is respectively connected to one end of the third capacitor and the seventh resistor, the other end of the third capacitor is grounded, the other end of the seventh resistor is connected to the base of the second triode, the emitter of the second triode is grounded, the collector of the second triode is connected to the control end, and the control end is used to cut off the input of the input end; the emitter of the second triode is grounded.
[0006] Through the above technical solution, when the current is very large, the optocoupler is turned on, and the power supply charges the capacitor through a small-resistance resistor. When the capacitor is charged, the voltage of the corresponding control-end transistor is greater than the preset value and is turned on. When the transistor is turned on, the collector is connected to the control end and the emitter is grounded, so that the control end receives a low-level signal. The control end cuts off the input of the input end according to the signal, and the capacitor is quickly charged to a full-load state, and then slowly discharges, forming a fast-charging and slow-discharging delay effect, avoiding the problem of continuous short circuit caused by the use of cement resistors in the existing technology, achieving the effect of delayed reset, and protecting the transistor used to trigger the short-circuit protection.
[0007] In some specific embodiments, the first power input terminal is connected to the output terminal of the circuit to be detected.
[0008] Through the above technical solutions, the circuit of the present application can be connected to various circuits to be tested that require short-circuit protection detection.
[0009] In some specific embodiments, the second resistor and the fifth resistor have the same resistance value.
[0010] In some specific embodiments, the third resistor and the fourth resistor have the same resistance value, and the third resistor and the fourth resistor are alloy resistors.
[0011] Through the above technical solution, the resistance of the small chip resistor is smaller, and the smaller the resistance, the smaller the heat generated.
[0012] In some specific embodiments, the resistance of the seventh resistor is greater than the resistance of the sixth resistor.
[0013] Through the above technical solution, the resistance values of the sixth and seventh resistors are set, and the third capacitor is used to achieve a fast charging and slow discharging delay effect.
[0014] In some specific embodiments, the resistance of the sixth resistor is 1K, and the resistance of the seventh resistor is 47K.
[0015] Through the above technical solution, the resistance values of the sixth and seventh resistors are set so that the short-circuit time is set to 1 / (1+47), thereby reducing the heat generation.
[0016] In some specific embodiments, the control terminal is connected to a main control chip, and the main control chip controls the input of the circuit to be detected.
[0017] Through the above technical solution, the external main control chip controls the input of the circuit to be detected.
[0018] In some specific embodiments, the second power input terminal is connected to an 18V load.
[0019] Through the above technical solution, the second input terminal is connected to an 18V load, and the 18V high voltage charges the third capacitor through a resistor. When the third capacitor is charged, the corresponding control terminal transistor voltage is greater than a preset value and will be turned on.
[0020] Compared with the prior art, the beneficial effects of the present invention are:
[0021] The detection port of the circuit to be detected is connected to the first power input terminal. When the current is very large, the optocoupler of the present application is turned on, the power supply is connected to the second power input terminal, and the capacitor is charged through a resistor with a small resistance. When the capacitor is charged, the voltage of the corresponding control-end transistor is greater than the preset value and is turned on. When the transistor is turned on, the control terminal is connected through the collector of the transistor and the emitter is grounded, so that the control terminal receives a low-level signal. The control terminal cuts off the input of the input terminal according to the signal, and the capacitor is quickly charged to a full load state, and then slowly discharges, forming a fast-charging and slow-discharging delay effect, avoiding the problem of continuously triggering short-circuit heating caused by using cement resistors for short-circuit detection in the prior art, thereby protecting the transistor used to trigger short-circuit protection. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate the embodiments and, together with the description, serve to explain the principles of the present invention. Other embodiments and many of the expected advantages of the embodiments will be readily apparent as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale with respect to each other. Like reference numerals designate corresponding similar parts.
[0023] Figure 1 A 24V system power supply circuit using an existing short-circuit protection detection circuit;
[0024] Figure 2 This is a circuit block diagram of the short-circuit protection detection circuit of this application;
[0025] Figure 3 A 24V system power supply circuit adopts the short-circuit protection detection circuit of this application. DETAILED DESCRIPTION
[0026] In the following detailed description, reference is made to the accompanying drawings, which form a part of the detailed description and are shown by way of illustrative specific embodiments in which the present invention may be practiced. In this regard, directional terms, such as "top," "bottom," "left," "right," "up," "down," etc., are used with reference to the orientation of the figures being described. Because the components of the embodiments may be positioned in several different orientations, directional terms are used for illustrative purposes and are in no way limiting. It should be understood that other embodiments may be utilized or logical changes may be made without departing from the scope of the present invention. The following detailed description should therefore not be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.
[0027] Figure 1 For a 24V system power supply circuit using the existing short-circuit protection detection circuit, refer to Figure 1 , consisting of resistors R36, R24, R39, R46, R48, diode Q3, and capacitor C3. Resistors R48 and R46 are large-resistance cement resistors. The heat generated by the cement resistors is used to divide the voltage. The voltage signal after voltage division is monitored to determine whether a short circuit has occurred. Because large-resistance cement resistors are used for short-circuit detection, continuous short circuits within 1s cause continuous heat accumulation. If the time is too long, the MOS tube Q3 used to trigger the short-circuit protection will overheat and eventually burn out.
[0028] The utility model proposes a short circuit protection detection circuit to solve the technical problems existing in the above-mentioned prior art. Figure 2 This is a circuit block diagram of the short circuit protection detection circuit according to the present application, refer to Figure 2The short-circuit protection detection circuit includes a first power input terminal IN1, a second power input terminal IN2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a first transistor Q1, a second transistor Q2, a first capacitor C1, a second capacitor C2, a third capacitor C3, and a photocoupler U1. The first power input terminal IN1 is connected to the first resistor R1 and then to the collector of the first transistor Q1. The base of the first transistor Q1 is electrically connected to one end of the first capacitor C1 and the second resistor R2. The other end of the second resistor R2 is respectively connected to one end of the third resistor R3, the fourth resistor R4 and the fifth resistor R5. One end of the fourth resistor R4 is also connected to the ground. The other ends of the third resistor R3 and the fourth resistor R4 are grounded. The other end of the fifth resistor R5 is connected to the One end is connected to the second capacitor C2 and then grounded, the other end of the fifth resistor R5 is also connected to the first input pin U1_IN1 of the optocoupler U1, the second input pin U1_IN2 of the optocoupler U1 is grounded, the third output pin U1_OUT1 of the optocoupler U1 is connected to the second power supply input terminal IN2, the fourth output pin U1_OUT2 of the optocoupler U1 is connected to one end of the sixth resistor R6, the other end of the sixth resistor R6 is respectively connected to one end of the third capacitor C3 and the seventh resistor R7, the other end of the third capacitor C3 is grounded, the other end of the seventh resistor R7 is connected to the base of the second transistor Q2, the emitter of the second transistor Q2 is grounded, the collector of the second transistor Q2 is connected to the control terminal OUT, and the control terminal OUT is used to shut off the input of the input terminal; the emitter of the second transistor Q2 is grounded. Through the above technical solution, when the current is very large, the optocoupler U1 is turned on, and the power supply charges the third capacitor C3 through a small-resistance resistor. When the third capacitor C3 is charged, the voltage of the corresponding second transistor Q2 at the control end is greater than the preset value and is turned on. When the second transistor Q2 is turned on, the collector is connected to the control end and the emitter is grounded, so that the control end OUT receives a low-level signal. The control end OUT cuts off the input of the first power input end IN1 according to the signal, and the third capacitor C3 is quickly charged to a full-load state, and then slowly discharges, forming a fast-charging and slow-discharging delay effect, avoiding the problem of continuous short circuit caused by the use of cement resistors in the prior art, achieving the effect of delayed reset, and protecting the first transistor Q1 used to trigger short-circuit protection.
[0029] Specifically, the second resistor R2 and the fifth resistor R5 have the same resistance value. The third resistor R3 and the fourth resistor R4 have the same resistance value, and the third resistor R3 and the fourth resistor R4 are alloy resistors. Small chip resistors have a smaller resistance value, and the smaller the resistance, the less heat is generated.
[0030] Specifically, the resistance of the seventh resistor R7 is greater than that of the sixth resistor R6. The resistance values of the sixth and seventh resistors R6 and R7 are set, and in conjunction with the third capacitor C3, a fast-charge and slow-discharge delay effect is achieved. For example, setting the resistance of the sixth resistor R6 to 1K and the resistance of the seventh resistor R7 to 47K can set the short-circuit time to 1 / (1+47), thereby reducing the heat generated by the short-circuit protection detection circuit.
[0031] Specifically, the control terminal OUT is connected to the main control chip, which controls the input of the circuit to be detected. The external main control chip controls the input of the circuit to be detected.
[0032] Specifically, the second power input terminal IN2 is connected to an 18V load. The 18V high voltage is passed through the sixth resistor R6 to charge the third capacitor C3. When the third capacitor C3 is charged, the corresponding control terminal second transistor Q2 is turned on when the voltage is greater than a preset value.
[0033] As an example, Figure 3 For a 24V system power supply circuit using the short-circuit protection detection circuit of this application, refer to Figure 3, resistors R36, R39, R64, R68, R24, R46 and R48 are used as the first resistor, the second resistor, the third resistor, the fourth resistor, the fifth resistor, the sixth resistor and the seventh resistor respectively, transistors Q3 and Q7 are used as the first transistor and the second transistor respectively, capacitors C3, C26 and C32 are used as the first capacitor, the second capacitor and the third capacitor respectively, and the photocoupler U6 is connected to the system power supply circuit composed of resistors R40, R18, VR2, R52, R53, R25, R30, R32, R34 and R23, capacitor C28, photocoupler U8, diode L2, and voltage regulator U10. Short-circuit protection detection is performed; among them, the resistance value of resistor R36 is 100, the resistance values of resistors R39 and R24 are both 2K, the capacitance value of capacitor C3 is 100NF, resistors R64 and R68 are both 400mR alloy resistors, the capacitance value of capacitor C26 is 1UF, the third output terminal of the photoelectric coupler is connected to an 18V high-voltage power supply, resistors R46 and R48 have resistance values of 1K and 47K respectively, the capacitance value of capacitor C32 is 1UF, the control terminal FB is connected to the main control chip, and a pin of the main control chip is connected to the first input terminal of the photoelectric coupler U8 of the system power supply, which is used to turn on or off the transformer output of the system power supply circuit. On the basis of the existing technology, this application adds a chip resistor plus an optocoupler feedback as a sampling resistor. The smaller the resistance, the less heat is generated. When the current is large, the optocoupler U6 is turned on. The optocoupler U6 is turned on, and the 18V high voltage charges the capacitor C32 through the 1K resistor. The capacitor C32 is charged, and the transistor Q7 is turned on when it is greater than 0.5V. When it is turned on, the signal of the main control chip is started, and the main control chip turns off the output of the transformer. The capacitor is fully charged and slowly discharges. The 1k fast charge and 47k slow discharge form a fast charge and slow discharge delay effect to avoid short circuit. That is, a short circuit of 1ms takes 47ms to reset.
[0034] This application achieves the following beneficial effects:
[0035] The detection port of the circuit to be detected is connected to the first power input terminal. When the current is very large, the optocoupler of the present application is turned on, the power supply is connected to the second power input terminal, and the capacitor is charged through a resistor with a small resistance. When the capacitor is charged, the voltage of the corresponding control-end transistor is greater than the preset value and is turned on. When the transistor is turned on, the control terminal is connected through the collector of the transistor and the emitter is grounded, so that the control terminal receives a low-level signal. The control terminal cuts off the input of the input terminal according to the signal, and the capacitor is quickly charged to a full load state, and then slowly discharges, forming a fast-charging and slow-discharging delay effect, avoiding the problem of continuously triggering short-circuit heating caused by using cement resistors for short-circuit detection in the prior art, thereby protecting the transistor used to trigger short-circuit protection.
[0036] Obviously, those skilled in the art can make various modifications and changes to the embodiments of the present invention without departing from the spirit and scope of the present invention. In this way, if these modifications and changes are within the scope of the claims of the present invention and their equivalents, the present invention is also intended to cover these modifications and changes. The word "comprising" does not exclude the presence of other elements or steps not listed in the claims. The simple fact that certain measures are recited in mutually different dependent claims does not indicate that the combination of these measures cannot be used to advantage. Any reference signs in the claims should not be considered as limiting the scope.
Claims
1. A short circuit protection detection circuit, characterized in that: The device comprises a first power input terminal, a second power input terminal, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a first transistor, a second transistor, a first capacitor, a second capacitor, a third capacitor, and a photocoupler, wherein the first power input terminal is connected to the first resistor and then to the collector of the first transistor, the base of the first transistor is electrically connected to one end of the first capacitor and the second resistor, the other end of the second resistor is respectively connected to one end of the third resistor, the fourth resistor, and the fifth resistor, one end of the fourth resistor is also connected to the ground, the other ends of the third resistor and the fourth resistor are grounded, and the other end of the fifth resistor is connected to the second transistor. The capacitor is grounded, the other end of the fifth resistor is also connected to the first input pin of the photoelectric coupler, the second input pin of the photoelectric coupler is grounded, the third output pin of the photoelectric coupler is connected to the second power supply input terminal, the fourth output pin of the photoelectric coupler is connected to one end of the sixth resistor, the other end of the sixth resistor is respectively connected to one end of the third capacitor and the seventh resistor, the other end of the third capacitor is grounded, the other end of the seventh resistor is connected to the base of the second transistor, the emitter of the second transistor is grounded, the collector of the second transistor is connected to the control terminal, and the control terminal is used to turn off the input of the input terminal; the emitter of the second transistor is grounded.
2. A short circuit protection detection circuit according to claim 1, characterized in that: The first power input terminal is connected to the output terminal of the circuit to be detected.
3. The short circuit protection detection circuit according to claim 1, characterized in that: The second resistor and the fifth resistor have the same resistance value.
4. The short circuit protection detection circuit according to claim 1, characterized in that: The third resistor and the fourth resistor have the same resistance value, and the third resistor and the fourth resistor are alloy resistors.
5. The short circuit protection detection circuit according to claim 1, characterized in that: The resistance of the seventh resistor is greater than the resistance of the sixth resistor.
6. The short circuit protection detection circuit according to claim 3, characterized in that: The resistance of the sixth resistor is 1K, and the resistance of the seventh resistor is 47K.
7. A short circuit protection detection circuit according to claim 2, characterized in that: The control end is connected to a main control chip, and the main control chip controls the input of the circuit to be detected.
8. The short circuit protection detection circuit according to claim 1, characterized in that: The second power input terminal is connected to an 18V load.