Output short-circuit protection circuit and device of constant-current output power supply and lighting product

Abstract

The invention relates to the technical field of lighting, and discloses an output short-circuit protection circuit and device of a constant-current output power supply and a lighting product, and the short-circuit protection circuit comprises a sampling circuit, a power supply circuit and an output circuit. The sampling circuit is connected with the output voltage end of the constant-current power supply circuit; the power supply circuit is connected with a power supply voltage source; the sampling circuit is provided with a first MOS tube, and the power supply circuit is provided with a second MOS tube. The drain electrode of the first MOS tube is communicated with the drain electrode of the second MOS tube through a second circuit; the power supply voltage source is communicated with the grid electrode of the second MOS tube through the third circuit, and the source electrode of the second MOS tube is connected with the output circuit; the output circuit is connected with a current feedback control circuit; the current feedback control circuit is connected with a power supply voltage source; the current feedback control circuit is connected with the constant-current power supply circuit; the first circuit and the second circuit are connected through a first resistor; the second circuit is connected with a second resistor. And the replacement burden of workers is relieved.

Description

Technical Field

[0001] The present application relates to the field of lighting technology, and more particularly to an output short-circuit protection circuit, device and lighting product of a constant current output power supply. Background Art

[0002] The power supply of LED lamps for lighting, the high-power driving power supply driven by pure analog chips, and the power supply requiring constant current output need to use a constant current source circuit. Due to the characteristics of the constant current source circuit, if the circuit is short-circuited, the current in the constant current source circuit will continue to output at the maximum current. Since the output current of the constant current source circuit in the short-circuit condition is the same as the output current of the constant current source circuit in the normal condition, it is difficult to detect even if the constant current source circuit is short-circuited. A short circuit will cause unnecessary waste of power, and there are certain safety hazards in the case of a short circuit.

[0003] In the prior art, a short-circuit protector is directly installed on the constant current source circuit. When a short circuit is detected in the constant current source circuit, the short-circuit protector directly trips and disconnects the output of the constant current source circuit. However, when the short-circuit protector is installed, the constant current source circuit needs to be manually closed to reconnect when the circuit is restored to normal, which increases the burden on the staff. Summary of the invention

[0004] The present application provides an output short-circuit protection circuit, device and lighting product of a constant current output power supply, aiming to solve the problem of increasing the burden on staff in the prior art.

[0005] In one embodiment, an output short-circuit protection circuit of a constant current output power supply is provided, which is used to detect the output voltage of the constant current power supply circuit, and the short-circuit protection circuit includes: a sampling circuit, a power supply circuit, and an output circuit; the sampling circuit is connected to the output voltage terminal of the constant current power supply circuit; the power supply circuit is connected to a power supply voltage source; a first MOS tube is provided on the sampling circuit, and a second MOS tube is provided on the power supply circuit;

[0006] Wherein, the sampling circuit is connected to the gate of the first MOS tube, the power supply voltage source is connected to the source of the first MOS tube through the first circuit, and the drain of the first MOS tube is connected to the drain of the second MOS tube through the second circuit; the power supply voltage source is connected to the gate of the second MOS tube through the third circuit, and the source of the second MOS tube is connected to the output circuit; the output circuit is connected to a current feedback control circuit; the current feedback control circuit is connected to the power supply voltage source; the current feedback control circuit is connected to the constant current power supply circuit; the first circuit and the second circuit are connected through a first resistor; the second circuit is connected to a second resistor, and the current of the power supply voltage source passes through the first resistor, the second resistor and the second MOS tube in sequence to enter the output circuit.

[0007] Among them, the current feedback control circuit is used to control the current constant current output of the output circuit; the current feedback control circuit is connected to the voltage feedback control circuit; and the voltage feedback control circuit is connected to the constant current power supply circuit.

[0008] In one solution, a voltage stabilizing diode is provided on the third circuit.

[0009] Specifically, the power supply voltage source is connected to the output pin of the voltage stabilizing diode, and the input pin of the voltage stabilizing diode is connected to the gate of the second MOS tube.

[0010] In one solution, the first resistor is connected in parallel with a first capacitor.

[0011] Specifically, two ends of the first capacitor are connected to two ends of the first resistor respectively.

[0012] In one embodiment, the voltage stabilizing diode is connected to the second circuit via a third resistor.

[0013] In one solution, the third resistor is connected in parallel with a second capacitor.

[0014] Specifically, two ends of the second capacitor are connected to two ends of the third resistor respectively.

[0015] In one solution, the sampling circuit is connected to two voltage-dividing resistors in sequence and then connected to the gate of the first MOS tube.

[0016] In one embodiment, the sampling circuit is connected to the two voltage-dividing resistors in sequence and then connected to a fourth resistor, and the fourth resistor is connected to the second circuit.

[0017] In one solution, the fourth resistor is connected in parallel with a third capacitor.

[0018] Specifically, two ends of the third capacitor are connected to two ends of the fourth resistor respectively.

[0019] In one embodiment, an output short-circuit protection device of a constant current output power supply is provided, and the output short-circuit protection device comprises a short-circuit protection circuit.

[0020] In one embodiment, a lighting product is provided, comprising the output short-circuit protection device.

[0021] Beneficial effects of this application:

[0022] By setting the mutual cooperation of the first MOS tube and the second MOS tube, when the constant current power supply circuit is short-circuited, the voltage of the sampling circuit is reduced, so that the sampling circuit cannot drive the first MOS tube to turn on, the first MOS tube is turned off, and the power supply voltage source charges the gate of the second MOS tube. When the charging voltage reaches the turn-on voltage of the second MOS tube, the second MOS tube is turned on, and the second resistor in the short-circuit protection circuit is connected to the current feedback control circuit. Due to the current connected to the short-circuit protection circuit, the current feedback control circuit controls the output current of the constant current source current to decrease. When the constant current power supply circuit is connected to a normal load, the first MOS tube is turned on, the second MOS tube is turned off, no signal is transmitted to the current feedback control circuit, and the constant current power supply circuit works normally. The short-circuit protection circuit can control the short-circuit current without manual closing, reducing the workload of the staff. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 This is a short-circuit protection circuit diagram in one embodiment of the present application;

[0025] Figure 2 This is a constant current power supply circuit diagram in one embodiment of the present application;

[0026] Figure 3 It is a current feedback control circuit in one embodiment of the present application;

[0027] Reference numerals in the figures:

[0028] 1. Constant current power supply circuit; 2. Short circuit protection circuit; 21. Sampling circuit; 211. First MOS tube; 212. Voltage divider resistor; 213. Fourth resistor; 22. Power supply circuit; 221. Second MOS tube; 23. Output circuit; 24. First circuit; 25. Second circuit; 26. Third circuit; 27. First resistor; 28. Second resistor; 29. ​​Third resistor; 3. Power supply voltage source; 4. Current feedback control circuit; 41. Operational amplifier; 5. Zener diode; 6. First capacitor; 7. Second capacitor; 8. Third capacitor. DETAILED DESCRIPTION

[0029] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0032] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0034] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0035] The present application makes improvements and innovations and proposes the following embodiments.

[0036] In some embodiments, see Figures 1 to 3 , an output short-circuit protection circuit of a constant current output power supply is provided, which is used to detect the output voltage of a constant current power supply circuit 1, and the short-circuit protection circuit 2 includes: a sampling circuit 21, a power supply circuit 22, and an output circuit 23; the sampling circuit 21 is connected to the output voltage end of the constant current power supply circuit 1; the power supply circuit 22 is connected to a power supply voltage source 3; a first MOS tube 211 is provided on the sampling circuit 21, and a second MOS tube 221 is provided on the power supply circuit 22;

[0037] Among them, the sampling circuit 21 is connected to the gate of the first MOS transistor 211, the power supply voltage source 3 is connected to the source of the first MOS transistor 211 through the first circuit 24, and the drain of the first MOS transistor 211 is connected to the drain of the second MOS transistor 221 through the second circuit 25; the power supply voltage source 3 is connected to the gate of the second MOS transistor 221 through the third circuit 26, and the source of the second MOS transistor 221 is connected to the output circuit 23; the output circuit 23 is connected to the current feedback control circuit 4; the current feedback control circuit 4 is connected to the power supply voltage source 3; the current feedback control circuit 4 is connected to the constant current power supply circuit 1; the first circuit 24 and the second circuit 25 are connected through the first resistor 27; the second circuit 25 is connected to the second resistor 28, and the current of the power supply voltage source 3 passes through the first resistor 27, the second resistor 28 and the second MOS transistor 221 in sequence and enters the output circuit 23.

[0038] The current feedback control circuit 4 is used to control the constant current output of the output circuit 23 ; the current feedback control circuit 4 is connected to the voltage feedback control circuit; and the voltage feedback control circuit is connected to the constant current power supply circuit 1 .

[0039] according to Figure 2 and Figure 3As shown, the current feedback control circuit 4 includes: an operational amplifier 41, whose positive input pin is connected to the output circuit 23 and the reference voltage circuit (ie Figure 3 The negative input pin is connected to the IS voltage in the constant current power supply circuit 1. When the voltages of the positive input pin and the negative input pin are the same, the operational amplifier 41 outputs at a predetermined value. At this time, the constant current power supply circuit 1 outputs a constant current at a predetermined current value. When the constant current power supply circuit 1 is short-circuited, the positive input pin is connected to the voltage of the output circuit 23, resulting in different voltages between the positive input pin and the negative input pin. At this time, the output current of the operational amplifier 41 is not a predetermined value. The current output by the operational amplifier 41 is fed back to the negative input pin through the capacitor C36 and the capacitor C105, and the constant current power supply circuit 1 controls the output IS voltage until the voltage of the negative input pin is the same as that of the positive input pin. That is, the regulation principle of the current feedback control circuit 4 is to make the voltages of the positive input pin and the negative input pin of the operational amplifier 41 the same, and the operational amplifier 41 stops regulating after outputting a predetermined signal. If the input voltage of the positive input pin is small, the voltage of the negative input pin will also decrease accordingly. Since the voltage of the positive input pin decreases after the positive input pin is connected to the second resistor, the voltage of the negative input pin will also decrease accordingly. The voltage of the negative input pin comes from the output voltage of the constant current power supply circuit 1, and the output voltage and current of the constant current power supply circuit 1 are reduced accordingly. Finally, the short-circuit protection function of the constant current power supply circuit 1 is achieved.

[0040] IS voltage indicates the power sampling resistor (i.e. Figure 2 The voltage across the resistor R145 in the circuit 1 is changed. As the voltage IS changes, the output current of the constant current power supply circuit 1 also changes.

[0041] like Figure 3 As shown, a resistor R167 and a resistor R168 are connected in parallel in the output circuit, and the resistor R167 and the resistor R168 are connected in parallel to the positive input pin.

[0042] When the constant current power supply circuit 1 is connected to a normal load, according to the formula, Among them, R167=2.4K, R168=13K, R25=100K, V REF3 =2.5V, R145=5mR; therefore, Io(normal)=10A.

[0043] Among them, R167 / / R168 represents the parallel resistance value of R167 and R168.

[0044] According to the Io(normal) formula of the constant current power supply circuit in the normal state, no matter the output current of the constant current power supply circuit is 10A, no matter how much the resistance of the load is, the output current is always 10A. If you want to change the output current of the constant current power supply circuit, you can change the resistance value of R145. The smaller the resistance value of R145, the greater the output current of the constant current power supply circuit.

[0045] When the constant current power supply circuit 1 is short-circuited, the voltage of the output circuit 23 is connected, so the formula is: Wherein R26=100R, and other values ​​remain unchanged, so Io(short)=0.48A. R26 is the second resistor 28.

[0046] Among them, R26 / / R167 / / R168 represents the parallel resistance value of R26, R167, and R168.

[0047] When the constant current power supply circuit 1 is short-circuited, I o (short) = 0.48A, which can greatly reduce the current during short circuit and reduce energy loss.

[0048] Specifically, when the resistance value of the second resistor 28 is increased, the current value of Io(short) will decrease; therefore, the short-circuit current of the constant current power supply circuit 1 can be changed by changing the resistance value of the second resistor 28 .

[0049] Connecting the short-circuit protection circuit 2 to the constant current power supply circuit 1 can greatly reduce the current during short circuit, thereby reducing the short-circuit power consumption of the constant current power supply circuit 1 and improving the short-circuit protection performance of the power supply and the reliability of the whole machine.

[0050] By setting the first MOS tube 211 and the second MOS tube 221 to cooperate with each other, when the constant current power supply circuit 1 is short-circuited, the voltage of the sampling circuit 21 is reduced, so that the sampling circuit 21 cannot drive the first MOS tube 211 to turn on, the first MOS tube 211 is turned off, and the power supply voltage source 3 charges the gate of the second MOS tube 221. When the charging voltage reaches the turn-on voltage of the second MOS tube 221, the second MOS tube 221 is turned on. After the second MOS tube 221 is turned on, the second resistor 28 is connected to Figure 3 In the current feedback control circuit 4, the second resistor 28 is connected in parallel with the resistor R167 and the resistor R168, thereby reducing Figure 3 The reference voltage at the positive input terminal of the operational amplifier 41 is adjusted by the operational amplifier 41 , and the voltage of the feedback control circuit 4 is also reduced, thereby reducing the output current.

[0051] When the constant current power supply circuit 1 is connected to a normal load, the first MOS tube 211 is turned on, the second MOS tube 221 is turned off, no signal is transmitted to the current feedback control circuit 4, and the constant current power supply circuit 1 works normally. The short-circuit protection circuit 2 can control the short-circuit current without manual closing, reducing the workload of the staff.

[0052] In some embodiments, a voltage regulator diode 5 is provided on the third circuit 26. The voltage regulator diode 5 can make the third circuit 26 start the second MOS tube 221 to conduct with a delay relative to the sampling circuit 21 starting the first MOS tube 211 to conduct, ensuring that the short-circuit protection circuit 2 will not operate at the moment of power on and during normal operation.

[0053] Specifically, the power supply voltage source 3 is connected to the output pin of the voltage stabilizing diode 5 , and the input pin of the voltage stabilizing diode 5 is connected to the gate of the second MOS transistor 221 .

[0054] In some embodiments, the first resistor 27 is connected in parallel with the first capacitor 6. The first capacitor 6 plays a delay role to ensure that the second MOS tube 221 does not operate during the normal startup process, thereby avoiding the output circuit 23 from being connected to the current feedback control circuit 4 under normal working conditions, and ensuring that the constant current power supply circuit 1 can output normal current.

[0055] Specifically, two ends of the first capacitor 6 are connected to two ends of the first resistor 27 respectively.

[0056] In some embodiments, the voltage stabilizing diode 5 is connected to the second circuit 25 via a third resistor 29. The third resistor 29 is used to cooperate with the second capacitor 7 to discharge the current on the gate of the second MOS transistor 221, so as to avoid the situation that the second MOS transistor 221 can be misled by a small signal interference when the constant current power supply circuit 1 is working normally.

[0057] In some implementations, the third resistor 29 is connected in parallel with the second capacitor 7. The second capacitor 7 is mainly used for filtering, reducing clutter, and preventing the second MOS tube 221 from malfunctioning due to interference signals of burrs.

[0058] Specifically, two ends of the second capacitor 7 are connected to two ends of the third resistor 29 respectively.

[0059] In some embodiments, the sampling circuit 21 is connected to the gate of the first MOS tube 211 after being connected to two voltage-dividing resistors 212 in sequence. The two voltage-dividing resistors 212 can divide the voltage of the sampling circuit 21, so that when the constant current power supply circuit 1 works normally, the voltage given to the gate of the first MOS tube 211 by the sampling circuit 21 is within a reasonable range, thereby ensuring the normal operation of the short-circuit protection circuit 2.

[0060] In some embodiments, the sampling circuit 21 is connected to two voltage-dividing resistors 212 in sequence and then connected to a fourth resistor 213, and the fourth resistor 213 is connected to the second circuit 25. The fourth resistor 213 is connected in series with the two voltage-dividing resistors 212 to divide the voltage and control the on and off of the first MOS tube 211.

[0061] In some embodiments, the fourth resistor 213 is connected in parallel with a third capacitor 8. The third capacitor 8 is used for filtering to reduce the influence of noise in the sampling circuit on the first MOS transistor 211, and the third capacitor 8 prevents the first MOS transistor 211 from malfunctioning due to interference signals from burrs.

[0062] Specifically, two ends of the third capacitor 8 are connected to two ends of the fourth resistor 213 respectively.

[0063] In some embodiments, an output short circuit protection device of a constant current output power supply is also provided, and the output short circuit protection device short circuit protection circuit has the same beneficial effect as that of the short circuit protection circuit, which will not be described in detail here.

[0064] In some embodiments, a lighting product is also provided, and the lighting product includes an output short-circuit protection device. The beneficial effect is the same as the effect of the short-circuit protection circuit, which will not be repeated here. The above is only an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An output short-circuit protection circuit of a constant current output power supply, used to detect the output voltage of a constant current power supply circuit, characterized in that: The short-circuit protection circuit comprises: a sampling circuit, a power supply circuit, and an output circuit; the sampling circuit is connected to the output voltage terminal of the constant current power supply circuit; the power supply circuit is connected to a power supply voltage source; a first MOS tube is arranged on the sampling circuit, and a second MOS tube is arranged on the power supply circuit; Wherein, the sampling circuit is connected to the gate of the first MOS tube, the power supply voltage source is connected to the source of the first MOS tube through the first circuit, and the drain of the first MOS tube is connected to the drain of the second MOS tube through the second circuit; the power supply voltage source is connected to the gate of the second MOS tube through the third circuit, and the source of the second MOS tube is connected to the output circuit; the output circuit is connected to a current feedback control circuit; the current feedback control circuit is connected to the power supply voltage source; the current feedback control circuit is connected to the constant current power supply circuit; the first circuit and the second circuit are connected through a first resistor; the second circuit is connected to a second resistor, and the current of the power supply voltage source passes through the first resistor, the second resistor and the second MOS tube in sequence to enter the output circuit.

2. The output short circuit protection circuit according to claim 1, characterized in that: The third circuit is provided with a voltage stabilizing diode.

3. The output short circuit protection circuit according to claim 1, characterized in that: The first resistor is connected in parallel with a first capacitor.

4. The output short circuit protection circuit according to claim 2, characterized in that: The voltage stabilizing diode is connected to the second circuit via a third resistor.

5. The output short circuit protection circuit according to claim 4, characterized in that: The third resistor is connected in parallel with the second capacitor.

6. The output short circuit protection circuit according to claim 1, characterized in that: The sampling circuit is connected to two voltage-dividing resistors in sequence and then connected to the gate of the first MOS tube.

7. The output short circuit protection circuit according to claim 6, characterized in that: The sampling circuit is connected to the two voltage-dividing resistors in sequence and then connected to a fourth resistor, and the fourth resistor is connected to the second circuit.

8. The output short circuit protection circuit according to claim 7, characterized in that: The fourth resistor is connected in parallel with a third capacitor.

9. An output short-circuit protection device for a constant current output power supply, characterized in that: The output short-circuit protection device comprises the short-circuit protection circuit according to any one of claims 1 to 8.

10. A lighting product, characterized in that: The lighting product comprises the output short-circuit protection device according to claim 9.

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