Dimming turn-off control circuit and driving power supply

Abstract

The utility model relates to a dimming turn-off control circuit and a driving power supply. The dimming turn-off control circuit comprises a voltage feedback module, a dimming turn-off module, a loop feedback module and a dummy load module, the dimming turn-off module is turned on according to the dimming turn-off signal and pulls down a voltage feedback signal output by the voltage feedback module when the dimming turn-off module is turned on and controls the dummy load module to start working; the loop feedback module outputs a turn-off feedback signal to the main control chip according to the pulled-down voltage feedback signal, so that the main control chip turns off the output according to the turn-off feedback signal; and the dummy load module forms a dummy load loop during working. The output voltage of the voltage feedback module and the output voltage of the driving power supply are reduced through the dimming turn-off module, the purpose of dimming turn-off is achieved, meanwhile, a dummy load loop is formed through the dummy load module after dimming turn-off, an auxiliary power supply winding keeps certain energy, the output voltage is kept stable, the turn-off effect can be achieved, and the service life of the driving power supply is prolonged. And the problem of dimming flickering can be avoided, the reliability is good, and the cost is low.

Description

Technical Field

[0001] The utility model relates to the technical field of driving power supplies, and more specifically to a dimming and shutoff control circuit and a driving power supply. Background Art

[0002] The principle of LED light emission is different from that of traditional lighting. It relies on PN junction to emit light. LED light sources with the same power have different current and voltage parameters due to the different chips they use. Therefore, their internal wiring structures and circuit distributions are also different, resulting in different requirements for dimming drive for light sources from different manufacturers. Therefore, the mismatch between control systems and light source appliances has become a common problem in the industry. At the same time, the diversification of LEDs has also put forward higher requirements for control systems. For example, sometimes the control system and lighting equipment need to be turned on instantly, or the lighting equipment needs to turn on some lamps and turn off some lamps. At this time, the LED power supply device needs to have the function of dimming and shutting down.

[0003] There are two main solutions for the existing LED power dimming shutdown circuit. The first solution is to add a standby power supply as the power supply (VCC) of the dimming control circuit, and control the primary IC to shut down and restart through a stable VCC. The second solution is: the power supply (VCC) of the dimming control circuit is powered by the auxiliary winding of the transformer, and when the dimming is turned off, the power feedback optocoupler is directly pulled down through the dimming shutdown signal (Vdim_off), and a MOS tube is added at the output end. The shutdown signal is used to control the MOS tube to shut down, thereby realizing dimming shutdown.

[0004] However, both of the above solutions have certain defects. For the first solution: the circuit is complex and the cost is high. In addition, the standby power supply needs to meet safety regulations, which requires additional PCB space, resulting in a large power supply volume and is not conducive to miniaturization design. For the second solution: the MOS tube has high stress during short-circuit testing, and there are defects in mass production, resulting in poor circuit reliability, and there is a risk of VCC power failure and restart, which is costly. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a dimming shutdown control circuit and a driving power supply.

[0006] The technical solution adopted by the utility model to solve the technical problem is: constructing a dimming shutdown control circuit, including: a voltage feedback module, a dimming shutdown module, a loop feedback module, and a dummy load module;

[0007] The input end of the voltage feedback module is connected to the output end of the driving power supply, the output end of the voltage feedback module is connected to the loop feedback module, the dimming shutdown module is respectively connected to the output end of the driving power supply, the voltage feedback module and the dummy load module, and the dummy load module is arranged at the output end of the driving power supply;

[0008] The dimming shutdown module is turned on according to the dimming shutdown signal, and when turned on, it pulls down the voltage feedback signal output by the voltage feedback module and controls the dummy load module to start working;

[0009] The loop feedback module outputs a shutdown feedback signal to the main control chip according to the pulled-down voltage feedback signal, so that the main control chip reduces the output voltage according to the shutdown feedback signal to shut down the load;

[0010] The dummy load module forms a dummy load loop based on the control of the dimming shutdown module to stabilize the output voltage.

[0011] In the dimming shutdown control circuit described in the utility model, the voltage feedback module includes: a voltage sampling circuit and a first operational amplifier circuit;

[0012] The input end of the voltage sampling circuit is connected to the output end of the driving power supply, the output end of the voltage sampling circuit is connected to the input end of the first operational amplifier circuit and the dimming shutdown module, and the output end of the first operational amplifier circuit is connected to the loop feedback module;

[0013] The voltage sampling circuit samples the output voltage of the driving power supply and obtains a voltage sampling signal;

[0014] The first operational amplifier circuit compares the voltage sampling signal with a voltage reference signal to obtain the voltage feedback signal.

[0015] In the dimming shutdown control circuit described in the utility model, the voltage sampling circuit includes: a ninth resistor, a tenth resistor, a first capacitor and a second capacitor; the first operational amplifier circuit includes: a thirteenth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, a thirteenth resistor, a fourteenth resistor and a first operational amplifier;

[0016] The input end of the ninth resistor is connected to the output end of the driving power supply, the output end of the ninth resistor is connected to the input end of the tenth resistor and the negative input end of the first operational amplifier, the output end of the tenth capacitor is grounded, the first capacitor is connected in parallel with the ninth resistor, and the second capacitor is connected in parallel with the tenth capacitor; the connection end between the ninth resistor and the tenth resistor is also connected to the dimming shutdown module;

[0017] The positive input terminal of the first operational amplifier is connected to the voltage reference signal through the thirteenth resistor, the positive input terminal of the first operational amplifier is also connected to the ground through the thirteenth resistor and the third capacitor in sequence, the negative input terminal of the first operational amplifier is also connected to its output terminal through the fourth capacitor and the fourteenth resistor in sequence, and the output terminal of the first operational amplifier is connected to the loop feedback module.

[0018] In the dimming shutdown control circuit described in the utility model, the dimming shutdown module includes: a signal receiving circuit, a voltage dividing circuit and a third switch circuit;

[0019] The input end of the voltage divider circuit is connected to the working voltage, the output end of the voltage divider circuit is respectively connected to the first end of the signal receiving circuit and the first end of the third switch circuit, the second end of the signal receiving circuit is grounded, and the second end of the third switch circuit is connected to the output end of the voltage sampling circuit;

[0020] The voltage dividing circuit performs voltage dividing processing on the working voltage;

[0021] The signal receiving circuit is turned on according to the dimming off signal, and when turned on, the third switch circuit is turned off, and the dummy load module is controlled to start working;

[0022] The third switch circuit is turned off according to the control of the signal receiving circuit to increase the voltage sampling signal to pull down the voltage feedback signal.

[0023] In the dimming shutdown control circuit of the utility model, the voltage divider circuit includes: a sixth resistor and a seventh resistor; the signal receiving circuit includes: a second photoelectric coupler; the third switch circuit includes: a third switch tube and an eighth resistor;

[0024] The first end of the seventh resistor is connected to the working voltage, the second end of the seventh resistor is connected to the first end of the sixth resistor, the first end of the second photoelectric coupler and the first end of the third switch, the second end of the sixth resistor is grounded, the second end of the second photoelectric coupler is grounded, the second end of the third switch tube is connected to the output end of the voltage sampling circuit through the eighth resistor, and the third end of the third switch tube is grounded.

[0025] In the dimming shutdown control circuit described in the utility model, the dummy load module includes: a load circuit, a first switch circuit and a second switch circuit;

[0026] The input end of the load circuit is connected to the output end of the driving power supply, the output end of the load circuit is grounded through the first switch circuit, the input end of the second switch circuit is connected to the working voltage, the output end of the second switch circuit is grounded, and the second switch circuit is also connected to the first switch circuit and the dimming shutdown module respectively.

[0027] In the dimming shutdown control circuit of the utility model, the load circuit includes one resistor or multiple resistors;

[0028] The multiple resistors are connected in series, in parallel, or in series and parallel.

[0029] In the dimming shutdown control circuit described in the utility model, the load circuit includes: a first resistor, a second resistor, a third resistor and a fourth resistor; the first switch circuit includes: a first switch tube; the second switch circuit includes: a second switch tube and a fifth resistor;

[0030] The first end of the first resistor is connected to the output end of the driving power supply, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the first end of the first switch tube, the third resistor is connected in parallel with the first resistor, and the fourth resistor is connected in parallel with the second resistor;

[0031] The second end of the first switch tube is connected to the first end of the second switch tube and the second end of the fifth resistor, the third end of the first switch tube and the third end of the second switch tube are grounded, the first end of the fifth resistor is connected to the working voltage, and the second end of the second switch tube is connected to the dimming shutdown module.

[0032] The dimming shutdown control circuit of the utility model further includes: a current feedback module; the input end of the current feedback module collects the output current of the driving power supply, and the output end of the current feedback module is connected to the loop feedback module;

[0033] The loop feedback module includes: an eighteenth resistor, a fourth photocoupler, a seventeenth resistor, a first diode, a fifteenth resistor and a sixteenth resistor; the current feedback module includes: a nineteenth resistor, a sixth capacitor, a seventh capacitor, a twentieth resistor, a twenty-first resistor, a twenty-third resistor, a twenty-fourth resistor, an eighth capacitor, a ninth capacitor and a second operational amplifier;

[0034] The first end of the eighteenth resistor is connected to the working voltage, the second end of the eighteenth resistor is connected to the input end of the fourth photoelectric coupler and the first end of the seventeenth resistor, the output end of the fourth photoelectric coupler is connected to the anode of the first diode and the second end of the seventeenth resistor, the cathode of the first diode is respectively connected to the first end of the fifteenth resistor and the first end of the sixteenth resistor, the second end of the fifteenth resistor is connected to the voltage feedback module, and the second end of the sixteenth resistor is connected to the output end of the second operational amplifier;

[0035] The negative input terminal of the second operational amplifier collects the output current of the driving power supply through the twentieth resistor, the nineteenth resistor and the seventh capacitor are connected in series in sequence and then connected in parallel to the negative input terminal and the output terminal of the second operational amplifier, the sixth capacitor is connected to the negative input terminal and the output terminal of the second operational amplifier, the positive input terminal of the second operational amplifier is connected to the second end of the twenty-fourth resistor and the first end of the twenty-third resistor through the twenty-first resistor, the first end of the twenty-fourth resistor is connected to the current reference signal, the second end of the twenty-third resistor is grounded, the first end of the eighth capacitor is connected to the negative input terminal of the second operational amplifier, the first end of the ninth capacitor is connected to the positive input terminal of the second operational amplifier, the second end of the eighth capacitor and the second end of the ninth capacitor are grounded.

[0036] The utility model also provides a driving power supply, comprising: the dimming shutoff control circuit mentioned above.

[0037] The dimming shutdown control circuit and driving power supply of the utility model have the following beneficial effects: including a voltage feedback module, a dimming shutdown module, a loop feedback module, and a dummy load module; the dimming shutdown module is turned on according to the dimming shutdown signal and pulls down the voltage feedback signal output by the voltage feedback module when turned on, and controls the dummy load module to start working; the loop feedback module outputs a shutdown feedback signal to the main control chip according to the pulled down voltage feedback signal, so that the main control chip shuts off the output according to the shutdown feedback signal; the dummy load module forms a dummy load loop when working. The utility model pulls down the output voltage of the voltage feedback module by the dimming shutdown module, reduces the output voltage of the driving power supply, and achieves the purpose of dimming shutdown. At the same time, after the dimming is shut down, a dummy load loop is formed by the dummy load module, so that the auxiliary power supply winding maintains a certain amount of energy and the output voltage remains stable, which can achieve the shutdown effect and avoid the problem of dimming flicker, and has good reliability and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0039] Figure 1This is a principle block diagram of the dimming and shutoff control circuit provided by the utility model;

[0040] Figure 2 The utility model provides a circuit schematic diagram of a dimming and shutoff control circuit. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0042] Figure 1 A preferred embodiment of the dimming shutdown control circuit provided by the utility model is shown. The dimming shutdown control circuit can reduce the output voltage of the driving power supply when receiving the dimming shutdown signal, so that the output voltage of the driving power supply is lower than the voltage required when the load is in a normal working state, thereby achieving the purpose of dimming shutdown (i.e., turning off the light). At the same time, while reducing the output voltage of the driving power supply, the dummy load is started to work to form a dummy load loop, so that the output voltage of the driving power supply is stabilized, thereby stabilizing the voltage of the auxiliary power supply. It can be understood that for the flyback circuit, a dummy load needs to be set when it is not loaded, otherwise the output voltage is not controlled when the output is no-load. Therefore, the utility model can stabilize the output voltage by setting a dummy load. At the same time, in the normal working state, the dummy load does not work, and only works when the dimming is turned off, thereby improving the efficiency of the driving power supply.

[0043] Specifically, Figure 1 As shown, in this embodiment, the dimming shutdown control circuit includes: a voltage feedback module 12 , a dimming shutdown module 13 , a loop feedback module 15 , and a dummy load module 14 .

[0044] The input end of the voltage feedback module 12 is connected to the output end of the driving power supply, the output end of the voltage feedback module 12 is connected to the loop feedback module 15, the dimming shutdown module 13 is respectively connected to the output end of the driving power supply, the voltage feedback module 12 and the dummy load module 14, and the dummy load module 14 is arranged at the output end of the driving power supply; the dimming shutdown module 13 is turned on according to the dimming shutdown signal, and when turned on, it pulls down the voltage feedback signal output by the voltage feedback module 12 and controls the dummy load module 14 to start working; the loop feedback module 15 outputs a shutdown feedback signal to the main control chip according to the pulled down voltage feedback signal, so that the main control chip reduces the output voltage according to the shutdown feedback signal to shut down the load; the dummy load module 14 forms a dummy load loop based on the control of the dimming shutdown module 13 to stabilize the output voltage.

[0045] Specifically, in this embodiment, when the driving power supply is working normally, since there is no dimming shutdown signal output, at this time, the dimming shutdown module 13 is not turned on, and the dummy load module 14 does not work. At the same time, the voltage feedback module 12 normally outputs the voltage feedback signal, and the driving power supply works normally; when the dimming is turned off, the dimming shutdown module 13 receives the dimming shutdown signal and turns on. At this time, due to the action of the dimming shutdown module 13, the voltage feedback signal output by the voltage feedback module 12 is pulled down, and then the main control chip detects the pulled down voltage feedback signal and reduces the output voltage of the driving power supply, so that the output voltage output by the driving power supply is lower than the working voltage required for the normal working state of the load, and the purpose of dimming shutdown is achieved (i.e., turning off the light). At the same time, due to the conduction of the dimming shutdown module 13, the dummy load module 14 is started, that is, the dummy load module 14 starts to work, and due to the action of the dummy load module 14, the output voltage can be stabilized, so that the output voltage is controllable, so that it can be completely shut down, and there will be no flashing phenomenon. It can be understood that dimming off (i.e. turning off the lights) is to adjust the voltage output by the driving power supply to below the working voltage of the lamp (lamp bead string), thereby turning off the lights. Although the lamp is still connected to the driving power supply in this state, it is no different from no-load. Compared with the traditional solution without a dummy load, after the lights are turned off, the main control chip will continuously detect the output voltage of the driving power supply. For example, if the output voltage increases, the voltage needs to be reduced. Therefore, the output end of the driving power supply does not have a stable state, which causes the lamp at the load end to flicker continuously. The utility model, by providing a dummy load module 14, can keep the auxiliary power supply winding at a certain energy after the dimming is turned off, thereby maintaining a stable output voltage at the output end of the driving power supply (the voltage is lower than the voltage of the lamp in the normal working state), and at the same time can provide a good working state for the isolated dimming to be turned on.

[0046] Furthermore, if Figure 1 As shown, the dimming shutdown control circuit further includes: a current feedback module 11 ; the input end of the current feedback module 11 collects the output current of the driving power supply, and the output end of the current feedback module 11 is connected to the loop feedback module 15 .

[0047] Specifically, in a preferred embodiment, the voltage feedback module 12 includes: a voltage sampling circuit 121 and a first operational amplifier circuit 122; the input end of the voltage sampling circuit 121 is connected to the output end of the driving power supply, the output end of the voltage sampling circuit 121 is connected to the input end of the first operational amplifier circuit 122 and the dimming shutdown module 13, and the output end of the first operational amplifier circuit 122 is connected to the loop feedback module 15; the voltage sampling circuit 121 samples the output voltage of the driving power supply and obtains a voltage sampling signal; the first operational amplifier circuit 122 compares the voltage sampling signal with the voltage reference signal to obtain a voltage feedback signal.

[0048] Specifically, in a preferred embodiment, the dimming shutdown module 13 includes: a signal receiving circuit 132 , a voltage dividing circuit 131 and a third switch circuit 133 .

[0049] The input end of the voltage divider circuit 131 is connected to the working voltage, the output end of the voltage divider circuit 131 is respectively connected to the first end of the signal receiving circuit 132 and the first end of the third switch circuit 133, the second end of the signal receiving circuit 132 is grounded, and the second end of the third switch circuit 133 is connected to the output end of the voltage sampling circuit 121; the voltage divider circuit 131 divides the working voltage; the signal receiving circuit 132 is turned on according to the dimming shutdown signal, and turns off the third switch circuit 133 when turned on, and controls the dummy load module 14 to start working; the third switch circuit 133 is turned off according to the control of the signal receiving circuit 132 to increase the voltage sampling signal to pull down the voltage feedback signal.

[0050] Specifically, in a preferred embodiment, the dummy load module 14 includes: a load circuit 141 , a first switch circuit 142 , and a second switch circuit 143 .

[0051] The input end of the load circuit 141 is connected to the output end of the driving power supply, the output end of the load circuit 141 is grounded through the first switch circuit 142, the input end of the second switch circuit 143 is connected to the working voltage, the output end of the second switch circuit 143 is grounded, and the second switch circuit 143 is also connected to the first switch circuit 142 and the dimming shutdown module 13 respectively. Among them, the load circuit 141 can include one resistor or multiple resistors; when multiple resistors are used, the multiple resistors are connected in series, in parallel, or in series and parallel. That is, the selection of the number and resistance value of the resistors in the load circuit 141 is based on the actual product requirements (i.e., the power to be borne), and the utility model does not make specific limitations.

[0052] The principle of the present utility model is described below with a specific embodiment.

[0053] Specifically, Figure 2 As shown, in this embodiment, the voltage sampling circuit 121 includes: a ninth resistor R9, a tenth resistor R10, a first capacitor C1 and a second capacitor C2; the first operational amplifier circuit 122 includes: a thirteenth resistor R13, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a thirteenth resistor R13, a fourteenth resistor R14 and a first operational amplifier U1-A.

[0054] The input end of the ninth resistor R9 is connected to the output end of the driving power supply, the output end of the ninth resistor R9 is connected to the input end of the tenth resistor R10 and the negative input end of the first operational amplifier U1-A, the output end of the tenth capacitor is grounded, the first capacitor C1 is connected in parallel with the ninth resistor R9, and the second capacitor C2 is connected in parallel with the tenth capacitor; the connection end of the ninth resistor R9 and the tenth resistor R10 is also connected to the dimming shutdown module 13; the positive input end of the first operational amplifier U1-A is connected to the voltage reference signal (i.e. Figure 2 The positive input terminal of the first operational amplifier U1-A is also connected to the ground through the thirteenth resistor R13 and the third capacitor C3 in sequence, the negative input terminal of the first operational amplifier U1-A is also connected to its output terminal through the fourth capacitor C4 and the fourteenth resistor R14 in sequence, and the output terminal of the first operational amplifier U1-A is connected to the loop feedback module 15.

[0055] like Figure 2 As shown, the voltage divider circuit 131 includes: a sixth resistor R6 and a seventh resistor R7; the signal receiving circuit 132 includes: a second photocoupler OT2-B; and the third switch circuit 133 includes: a third switch tube Q3 and an eighth resistor R8.

[0056] The first end of the seventh resistor R7 is connected to the working voltage (i.e., VDD in the figure), the second end of the seventh resistor R7 is connected to the first end of the sixth resistor R6, the first end of the second photocoupler OT2-B and the first end of the third switch, the second end of the sixth resistor R6 is grounded, the second end of the second photocoupler OT2-B is grounded, the second end of the third switch tube Q3 is connected to the output end of the voltage sampling circuit 121 (i.e., the connection end of the ninth resistor R9 and the tenth resistor R10) through the eighth resistor R8, and the third end of the third switch tube Q3 is grounded.

[0057] Optionally, in this embodiment, if Figure 2 As shown, the third switch tube Q3 can be a MOS tube, wherein the first end of the third switch tube Q3 is the gate of the MOS tube, the second end of the third switch tube Q3 is the drain of the MOS tube, and the third end of the third switch tube Q3 is the source of the MOS tube.

[0058] like Figure 2 As shown, the load circuit 141 includes: a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4; the first switch circuit 142 includes: a first switch tube Q1; and the second switch circuit 143 includes: a second switch tube Q2 and a fifth resistor R5.

[0059] The first end of the first resistor R1 is connected to the output end of the driving power supply, the second end of the first resistor R1 is connected to the first end of the second resistor R2, the second end of the second resistor R2 is connected to the first end of the first switch tube Q1, the third resistor R3 is connected in parallel with the first resistor R1, and the fourth resistor R4 is connected in parallel with the second resistor R2; the second end of the first switch tube Q1 is connected to the first end of the second switch tube Q2 and the second end of the fifth resistor R5, the third end of the first switch tube Q1 and the third end of the second switch tube Q2 are grounded, the first end of the fifth resistor R5 is connected to the working voltage, and the second end of the second switch tube Q2 is connected to the dimming shutdown module 13.

[0060] Optionally, in this embodiment, the first switch tube Q1 may be a triode, and the second switch tube Q2 may be a MOS tube. The first end of the first switch tube Q1 is the collector of the triode, the second end of the first switch tube Q1 is the base of the triode, and the third end of the first switch tube Q1 is the emitter of the triode. The first end of the second switch tube Q2 is the drain of the MOS tube, the second end of the second switch tube Q2 is the gate of the MOS tube, and the third end of the second switch tube Q2 is the source of the MOS tube.

[0061] like Figure 2 As shown, in this embodiment, the loop feedback module 15 includes: an eighteenth resistor R18, a fourth photocoupler OT4-A, a seventeenth resistor R17, a first diode D1, a fifteenth resistor R15 and a sixteenth resistor R16; the current feedback module 11 includes: a nineteenth resistor R19, a sixth capacitor C6, a seventh capacitor C7, a twentieth resistor R20, a twenty-first resistor R21, a twenty-third resistor R23, a twenty-fourth resistor R24, an eighth capacitor C8, a ninth capacitor C9 and a second operational amplifier U1-B.

[0062] The first end of the eighteenth resistor R18 is connected to the working voltage, the second end of the eighteenth resistor R18 is connected to the input end of the fourth photocoupler OT4-A and the first end of the seventeenth resistor R17, the output end of the fourth photocoupler OT4-A is connected to the anode of the first diode D1 and the second end of the seventeenth resistor R17, the cathode of the first diode D1 is respectively connected to the first end of the fifteenth resistor R15 and the first end of the sixteenth resistor R16, the second end of the fifteenth resistor R15 is connected to the voltage feedback module 12 (that is, the output end of the first operational amplifier U1-A), and the second end of the sixteenth resistor R16 is connected to the output end of the second operational amplifier U1-B; the negative input end of the second operational amplifier U1-B collects the output current of the driving power supply through the twentieth resistor R20 (that is, Figure 2IS in the figure), the nineteenth resistor R19 and the seventh capacitor C7 are sequentially connected in series and then connected in parallel to the negative input terminal and the output terminal of the second operational amplifier U1-B, the sixth capacitor C6 is connected to the negative input terminal and the output terminal of the second operational amplifier U1-B, the positive input terminal of the second operational amplifier U1-B is connected to the second end of the twenty-fourth resistor R24 ​​and the first end of the twenty-third resistor R23 through the twenty-first resistor R21, and the first end of the twenty-fourth resistor R24 ​​is connected to the current reference signal (i.e. Figure 2 IREF in the figure), a second end of the twenty-third resistor R23 is grounded, a first end of the eighth capacitor C8 is connected to the negative input terminal of the second operational amplifier U1-B, a first end of the ninth capacitor C9 is connected to the positive input terminal of the second operational amplifier U1-B, and a second end of the eighth capacitor C8 and a second end of the ninth capacitor C9 are grounded.

[0063] Specifically, Figure 2 As shown, when the driving power supply is working normally, since no shutdown signal is received, the second photocoupler OT2-B is not turned on. At this time, the third switch tube Q3 is also not turned on, so that the eighth resistor R8 is connected in parallel with the tenth resistor R10, and the resistance of the two resistors in parallel becomes smaller. Therefore, at this time, the voltage value of the negative input terminal of the first operational amplifier U1-A becomes smaller, and the output terminal of the first operational amplifier U1-A outputs a high-level signal, thereby increasing the energy feedback of the fourth photocoupler OT4-A. At this time, the main control chip adjusts the output voltage of the driving power supply based on the energy feedback of the fourth photocoupler OT4-A, so that the output voltage of the driving power supply is greater than the output voltage in the shutdown state. At this time, the output voltage can turn on the lamp beads on the lamp board, and the lamp beads are lit normally. After the lamp beads are lit normally, the current collection end (i.e., the IS end) of the current feedback module 11 collects the output current, and the current feedback module 11 starts to work. At this time, the voltage feedback module 12 starts to exit work, and the current feedback module 11 forms a negative feedback working loop, giving a constant output current, so that the driving power supply maintains a constant current mode. At the same time, since the second photocoupler OT2-B is not conducting, the second switch tube Q2 is conducting, so that the first switch tube Q1 is not conducting, and then the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 do not form a loop and do not participate in the work.

[0064] When the dimming of the driving power supply is turned off, the second photocoupler OT2-B receives the dimming shutdown signal and turns on. At this time, the third switch tube Q3 is cut off, and the eighth resistor R8 is disconnected from the parallel connection with the tenth resistor R10. At this time, the voltage at the negative input terminal of the first operational amplifier U1-A increases, and the output terminal of the first operational amplifier U1-A outputs a low level, so that the energy feedback of the fourth photocoupler OT4-A is reduced. Based on this, the main control chip reduces the output voltage of the driving power supply. At this time, the output voltage is lower than the voltage required for the normal working state of the lamp beads, and the lamp beads on the lamp board are not turned on, causing the lamp beads to go out. When the lamp bead is extinguished, the output end cannot form a circuit loop, the current feedback module 11 does not work, and the output voltage is constant in a region lower than the minimum VF value voltage of the lamp board lamp bead. At this time, the working voltage of the driving power supply is low, so the auxiliary winding power supply energy may be insufficient. Based on this, the utility model starts the dummy load module 14 to make the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 work with reference to the output circuit loop to form a dummy load, thereby ensuring that the auxiliary winding maintains a certain power supply energy and maintains a stable output voltage.

[0065] It should be noted that the main control chip used in the present invention is a conventional main control chip in a driving power supply, and the present invention does not make any improvements to its internal program, but only uses its existing functions.

[0066] The utility model adopts a simple circuit to realize dimming and shutting down, and has good stability and reliability, low cost, can save PCB space, save device cost, and will not cause the problem of incomplete shutting down.

[0067] The utility model further provides a driving power supply, comprising: the dimming shutdown control circuit disclosed in the embodiment of the utility model. Optionally, the driving power supply can be an LED driving power supply.

[0068] The above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with the technology to understand the content of the utility model and implement it accordingly, and they cannot limit the protection scope of the utility model. All equivalent changes and modifications made to the scope of the claims of the utility model should fall within the scope of the claims of the utility model.

Claims

1. A dimming shutdown control circuit, characterized in that: include: Voltage feedback module, dimming shutdown module, loop feedback module, dummy load module; The input end of the voltage feedback module is connected to the output end of the driving power supply, the output end of the voltage feedback module is connected to the loop feedback module, the dimming shutdown module is respectively connected to the output end of the driving power supply, the voltage feedback module and the dummy load module, and the dummy load module is arranged at the output end of the driving power supply; The dimming shutdown module is turned on according to the dimming shutdown signal, and when turned on, it pulls down the voltage feedback signal output by the voltage feedback module and controls the dummy load module to start working; The loop feedback module outputs a shutdown feedback signal to the main control chip according to the pulled-down voltage feedback signal, so that the main control chip reduces the output voltage according to the shutdown feedback signal to shut down the load; The dummy load module forms a dummy load loop based on the control of the dimming shutdown module to stabilize the output voltage.

2. The dimming shutdown control circuit according to claim 1, characterized in that: The voltage feedback module includes: a voltage sampling circuit and a first operational amplifier circuit; The input end of the voltage sampling circuit is connected to the output end of the driving power supply, the output end of the voltage sampling circuit is connected to the input end of the first operational amplifier circuit and the dimming shutdown module, and the output end of the first operational amplifier circuit is connected to the loop feedback module; The voltage sampling circuit samples the output voltage of the driving power supply and obtains a voltage sampling signal; The first operational amplifier circuit compares the voltage sampling signal with a voltage reference signal to obtain the voltage feedback signal.

3. The dimming shutdown control circuit according to claim 2, characterized in that: The voltage sampling circuit includes: a ninth resistor, a tenth resistor, a first capacitor and a second capacitor; the first operational amplifier circuit includes: a thirteenth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, a thirteenth resistor, a fourteenth resistor and a first operational amplifier; The input end of the ninth resistor is connected to the output end of the driving power supply, the output end of the ninth resistor is connected to the input end of the tenth resistor and the negative input end of the first operational amplifier, the output end of the tenth resistor is grounded, the first capacitor is connected in parallel with the ninth resistor, and the second capacitor is connected in parallel with the tenth resistor; the connection end between the ninth resistor and the tenth resistor is also connected to the dimming shutdown module; The positive input terminal of the first operational amplifier is connected to the voltage reference signal through the thirteenth resistor, the positive input terminal of the first operational amplifier is also connected to the ground through the thirteenth resistor and the third capacitor in sequence, the negative input terminal of the first operational amplifier is also connected to its output terminal through the fourth capacitor and the fourteenth resistor in sequence, and the output terminal of the first operational amplifier is connected to the loop feedback module.

4. The dimming shutdown control circuit according to claim 2, characterized in that: The dimming shutdown module includes: a signal receiving circuit, a voltage dividing circuit and a third switch circuit; The input end of the voltage divider circuit is connected to the working voltage, the output end of the voltage divider circuit is respectively connected to the first end of the signal receiving circuit and the first end of the third switch circuit, the second end of the signal receiving circuit is grounded, and the second end of the third switch circuit is connected to the output end of the voltage sampling circuit; The voltage dividing circuit performs voltage dividing processing on the working voltage; The signal receiving circuit is turned on according to the dimming off signal, and when turned on, the third switch circuit is turned off, and the dummy load module is controlled to start working; The third switch circuit is turned off according to the control of the signal receiving circuit to increase the voltage sampling signal to pull down the voltage feedback signal.

5. The dimming shutdown control circuit according to claim 4, characterized in that: The voltage divider circuit includes: a sixth resistor and a seventh resistor; the signal receiving circuit includes: a second photoelectric coupler; the third switch circuit includes: a third switch tube and an eighth resistor; The first end of the seventh resistor is connected to the working voltage, the second end of the seventh resistor is connected to the first end of the sixth resistor, the first end of the second photoelectric coupler and the first end of the third switch, the second end of the sixth resistor is grounded, the second end of the second photoelectric coupler is grounded, the second end of the third switch tube is connected to the output end of the voltage sampling circuit through the eighth resistor, and the third end of the third switch tube is grounded.

6. The dimming shutdown control circuit according to claim 1, characterized in that: The dummy load module comprises: a load circuit, a first switch circuit and a second switch circuit; The input end of the load circuit is connected to the output end of the driving power supply, the output end of the load circuit is grounded through the first switch circuit, the input end of the second switch circuit is connected to the working voltage, the output end of the second switch circuit is grounded, and the second switch circuit is also connected to the first switch circuit and the dimming shutdown module respectively.

7. The dimming shutdown control circuit according to claim 6, characterized in that: The load circuit includes one resistor or multiple resistors; The multiple resistors are connected in series, in parallel, or in series and parallel.

8. The dimming shutdown control circuit according to claim 6, characterized in that: The load circuit includes: a first resistor, a second resistor, a third resistor and a fourth resistor; the first switch circuit includes: a first switch tube; the second switch circuit includes: a second switch tube and a fifth resistor; The first end of the first resistor is connected to the output end of the driving power supply, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the first end of the first switch tube, the third resistor is connected in parallel with the first resistor, and the fourth resistor is connected in parallel with the second resistor; The second end of the first switch tube is connected to the first end of the second switch tube and the second end of the fifth resistor, the third end of the first switch tube and the third end of the second switch tube are grounded, the first end of the fifth resistor is connected to the working voltage, and the second end of the second switch tube is connected to the dimming shutdown module.

9. The dimming shutdown control circuit according to any one of claims 1 to 8, characterized in that: Also includes: Current feedback module; The input end of the current feedback module collects the output current of the driving power supply, and the output end of the current feedback module is connected to the loop feedback module; The loop feedback module includes: an eighteenth resistor, a fourth photocoupler, a seventeenth resistor, a first diode, a fifteenth resistor and a sixteenth resistor; the current feedback module includes: a nineteenth resistor, a sixth capacitor, a seventh capacitor, a twentieth resistor, a twenty-first resistor, a twenty-third resistor, a twenty-fourth resistor, an eighth capacitor, a ninth capacitor and a second operational amplifier; The first end of the eighteenth resistor is connected to the working voltage, the second end of the eighteenth resistor is connected to the input end of the fourth photoelectric coupler and the first end of the seventeenth resistor, the output end of the fourth photoelectric coupler is connected to the anode of the first diode and the second end of the seventeenth resistor, the cathode of the first diode is respectively connected to the first end of the fifteenth resistor and the first end of the sixteenth resistor, the second end of the fifteenth resistor is connected to the voltage feedback module, and the second end of the sixteenth resistor is connected to the output end of the second operational amplifier; The negative input terminal of the second operational amplifier collects the output current of the driving power supply through the twentieth resistor, the nineteenth resistor and the seventh capacitor are connected in series in sequence and then connected in parallel to the negative input terminal and the output terminal of the second operational amplifier, the sixth capacitor is connected to the negative input terminal and the output terminal of the second operational amplifier, the positive input terminal of the second operational amplifier is connected to the second end of the twenty-fourth resistor and the first end of the twenty-third resistor through the twenty-first resistor, the first end of the twenty-fourth resistor is connected to the current reference signal, the second end of the twenty-third resistor is grounded, the first end of the eighth capacitor is connected to the negative input terminal of the second operational amplifier, the first end of the ninth capacitor is connected to the positive input terminal of the second operational amplifier, the second end of the eighth capacitor and the second end of the ninth capacitor are grounded.

10. A driving power supply, characterized in that: include: The dimming shutdown control circuit according to any one of claims 1 to 9.

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