A fast shutdown LED lamp control circuit that cuts off output current

Abstract

The present invention provides a fast shutdown LED lamp control circuit for cutting off output current, comprising a sampling circuit and a control circuit; the sampling circuit is connected to a control module, the control module is connected to a switch module, and the switch module is connected to an LED load; the sampling circuit receives a level signal and sends it to the control module, the control module controls the switch module to turn on or off, thereby controlling the LED load to be powered on or off; the two ends of the LED load are respectively connected to the switch module and the control module, and the switch module is connected to an LED drive control device. The application of this technical solution can realize the fast shutdown function of the LED lamp control circuit.

Description

Technical Field

[0001] The invention relates to the field of LED lighting, and in particular to a fast shutdown LED lamp control circuit for cutting off output current. Background Art

[0002] In the LED lighting industry, there are often time requirements for the shutdown process of LED lights, and some special application sites have more stringent requirements for the shutdown time. At present, using conventional solutions, it is difficult to achieve the effect of quickly turning off the light when shutting down by connecting a continuous discharge resistor in parallel at the output end of the circuit. In actual use, in order to reduce flicker and other reasons, a relatively large capacitor is usually connected in parallel at the output end of the circuit. This capacitor will discharge the LED after shutting down, which will cause it to not be extinguished immediately after shutting down. The commonly used method is to connect a discharge resistor in parallel at both ends of the output capacitor, or to speed up the discharge by connecting a resistor after shutting down. But no matter what, the output capacitor cannot be fully discharged immediately, and it takes a certain amount of time, which will cause it to be unable to shut down quickly and fail to achieve the effect of quick shutdown. Summary of the invention

[0003] The object of the present invention is to provide a fast shutdown LED lamp control circuit for cutting off output current, so as to realize fast shutdown of the LED lamp control circuit.

[0004] In order to solve the above technical problems, the present invention provides a fast shutdown LED lamp control circuit for cutting off the output current, including a sampling circuit and a control circuit; the sampling circuit is connected to a control module, the control module is connected to a switch module, and the switch module is connected to an LED load; the sampling circuit receives a level signal and sends it to the control module, the control module controls the switch module to turn on or off, thereby controlling the LED load to be powered on or off; the two ends of the LED load are respectively connected to the switch module and the control module, and the switch module is connected to an LED drive control device.

[0005] In a preferred embodiment, the control module includes a first control device, a second control device and a third control device; the sampling circuit is connected to the first control device, the first control device is connected to the second control device, the second control device is connected to the third control device, and the third control device is connected to the switch module.

[0006] In a preferred embodiment, a discharge circuit is further included; one end of the discharge circuit is connected to the LED drive control device and the control device, and the other end of the discharge circuit is connected to the LED load.

[0007] In a preferred embodiment, the first control device includes a first switch tube, a voltage regulator diode and a first resistor; the second control device includes a second switch tube, a second resistor and a third resistor; the third control device includes a third switch tube, a fourth resistor and a fifth resistor; the switch module includes a fourth switch tube and a sixth resistor.

[0008] In a preferred embodiment, the gate of the first switch tube is connected to the sampling circuit, the source of the first switch tube is grounded, the drain of the first switch tube is connected to one end of the first resistor, and the other end of the first resistor is connected to the gate of the second switch tube and one end of the second resistor;

[0009] The gate of the second switch tube is connected to one end of the second resistor connected to the first resistor, and the other end of the second resistor is connected to the positive electrode of the discharge circuit; the drain of the second switch tube is connected to the negative electrode of the LED load, the source of the second switch tube is connected to one end of the third resistor, and the other end of the third resistor is connected to the gate of the fourth switch tube;

[0010] The gate of the third switch tube is connected to the source of the second switch tube and one end of the fourth resistor, and the other end of the fourth resistor is connected to the positive electrode of the discharge circuit; the source of the third switch tube is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the negative electrode of the LED load; the drain of the third switch tube is connected to the positive electrode of the discharge circuit.

[0011] In a preferred embodiment, one end of the sixth resistor is connected to the gate of the fourth switch tube, and the other end of the sixth resistor is connected to the source of the fourth switch tube and the positive electrode of the discharge circuit; the drain of the fourth switch tube is connected to the positive electrode of the LED load.

[0012] In a preferred embodiment, it further includes a rectifier circuit and an isolation device, wherein the rectifier circuit is connected to the isolation device, and one end of the sampling circuit is connected between the rectifier circuit and the isolation device.

[0013] In a preferred embodiment, the sampling circuit includes a seventh resistor, an eighth resistor and a first capacitor; one end of the seventh resistor is connected between the rectifier circuit and the isolation device, the other end of the seventh resistor is connected to one end of the eighth resistor, the other end of the eighth resistor is grounded, one end of the first capacitor is connected between the seventh resistor and the eighth resistor, the other end of the first capacitor is grounded, and the voltage regulator diode is connected in parallel to both ends of the first capacitor; the discharge circuit is specifically a polarized output capacitor.

[0014] In a preferred embodiment, in a normal working state, the power input outputs a high level after passing through the rectifier circuit and is stepped down through the seventh resistor and added to the upper end of the first capacitor. The first capacitor smoothes its voltage and then adds it to the gate of the first switch tube to turn it on. Then the gate voltage of the second switch tube drops, turning on the second switch tube, and then the third switch tube is turned off. Since the third switch tube is in the off state, the output capacitor will not discharge through the third switch tube at this time; and since the second switch tube is turned on, the fourth switch tube is also turned on; so the output is normal and the operation of the LED load is not affected.

[0015] In a preferred embodiment, in the shutdown instant state: the rectifier circuit has no output, and the isolation device has an isolation function. The gate of the first switch tube is made low level through the seventh resistor, and the first switch tube enters the shutdown state, and then the gate voltage of the second switch tube increases, causing the second switch tube to be turned off, and then the gate voltage of the third switch tube increases, and the third switch tube is turned on. At this time, the output capacitor is discharged through the third switch tube. During the discharge period of the output capacitor, because the second switch tube is turned off, the gate voltage of the fourth switch tube increases, and the fourth switch tube is also turned off, and the LED load is disconnected and shut down.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0017] The present invention provides a fast shutdown LED lamp control circuit that cuts off the output current. The fourth switch tube is set to directly control the power on of the LED load; the second switch tube directly controls the switch of the fourth switch tube, so that the fourth switch tube directly controls its switch according to whether the circuit is powered on; the discharge circuit is not directly connected to the LED load, and the current of the LED load can be cut off when shutting down regardless of whether the output capacitor energy is fully discharged, and the LED load does not need to wait for the discharge circuit to be fully discharged before turning off the LED lamp. Therefore, the LED lamp can be turned off quickly to achieve a fast shutdown function. The present invention has wide applicability and good compatibility with LED drive circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The schematic diagram of a fast shutdown LED lamp control circuit for cutting off output current in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0020] A fast shutdown LED lamp control circuit that cuts off the output current, reference Figure 1, including a rectifier circuit BD1, an isolation device, and a sampling circuit; the rectifier circuit BD1 is connected to the isolation device, one end of the sampling circuit is arranged between the rectifier circuit BD1 and the isolation device, the other end of the sampling circuit is connected to a control module, the control module is connected to a switch module, and the switch module is connected to an LED load; the sampling circuit receives a level signal and sends it to the control module, the control module controls the switch module to turn on or off, thereby controlling the LED load to be powered on or off. The two ends of the LED load are respectively connected to the switch module and the control module, and the switch module is connected to an LED drive control device.

[0021] Specifically, the control module includes a first control device, a second control device and a third control device; the sampling circuit is connected to the first control device, the first control device is connected to the second control device, the second control device is connected to the third control device, and the third control device is connected to the switch module. It also includes a discharge circuit; one end of the discharge circuit is connected to the LED drive control device and the control device, and the other end of the discharge circuit is connected to the LED load.

[0022] The following describes the circuit schematic diagram of this patent in combination with specific circuit elements:

[0023] The first control device includes a first switch tube Q1, a voltage stabilizing diode Z1 and a first resistor R6; the second control device includes a second switch tube Q2, a second resistor R3 and a third resistor R10; the third control device includes a third switch tube Q3, a fourth resistor R2 and a fifth resistor R8; the switch module includes a fourth switch tube Q4 and a sixth resistor R9. In this embodiment, the first switch tube Q1 and the third switch tube Q3 are specifically NMOS tubes, and the second switch tube Q2 and the fourth switch tube Q4 are specifically PMOS tubes. Other switch tubes or switch tubes such as relays, optocouplers, etc. can also be used, and the protection scope of the present invention cannot be limited by this.

[0024] The gate of the first switch tube Q1 is connected to the sampling circuit, the source of the first switch tube Q1 is grounded, the drain of the first switch tube Q1 is connected to one end of the first resistor R6, and the other end of the first resistor R6 is connected to the gate of the second switch tube Q2 and one end of the second resistor R3;

[0025] The gate of the second switch tube Q2 is connected to one end of the second resistor R3 connected to the first resistor R6, and the other end of the second resistor R3 is connected to the positive electrode of the discharge circuit; the drain of the second switch tube Q2 is connected to the negative electrode of the LED load, the source of the second switch tube Q2 is connected to one end of the third resistor R10, and the other end of the third resistor R10 is connected to the gate of the fourth switch tube Q4;

[0026] The gate of the third switch tube Q3 is connected to the source of the second switch tube Q2 and one end of the fourth resistor R2, and the other end of the fourth resistor R2 is connected to the positive electrode of the discharge circuit; the source of the third switch tube Q3 is connected to one end of the fifth resistor R8, and the other end of the fifth resistor R8 is connected to the negative electrode of the LED load; the drain of the third switch tube Q3 is connected to the positive electrode of the discharge circuit.

[0027] One end of the sixth resistor R9 is connected to the gate of the fourth switch tube Q4, and the other end of the sixth resistor R9 is connected to the source of the fourth switch tube Q4 and the positive electrode of the discharge circuit; the drain of the fourth switch tube Q4 is connected to the positive electrode of the LED load.

[0028] The sampling circuit includes a seventh resistor R4, an eighth resistor R5 and a first capacitor C1; one end of the seventh resistor R4 is connected between the rectifier circuit BD1 and the isolation device, the other end of the seventh resistor R4 is connected to one end of the eighth resistor R5, the other end of the eighth resistor R5 is grounded, one end of the first capacitor C1 is connected between the seventh resistor R4 and the eighth resistor R5, the other end of the first capacitor C1 is grounded, and the Zener diode Z1 is connected in parallel to both ends of the first capacitor C1; the discharge circuit is specifically a polarized output capacitor E1.

[0029] Specifically, the rectifier circuit BD1 is specifically a rectifier bridge, the isolation device is specifically a diode D1, the positive electrode of the diode D1 is connected to the rectifier bridge, the negative electrode of the diode D1 is connected to a filter circuit, the other end of the filter circuit is connected to the LED drive control device, the LED drive control device has a positive output interface LED+ and a negative output interface LED-, the positive output interface LED+ is connected to the positive electrode of the output capacitor E1, the negative output interface LED- is connected to the negative electrode of the output capacitor E1, the positive electrode of the output capacitor E1 is connected to the source of the fourth switch tube Q4, and the negative electrode of the output capacitor E1 is connected to the negative electrode of the LED load. For the convenience of description, the sampling point B+ is taken between the rectifier circuit BD1 and the isolation device. Other positions can also be set as the sampling point B+. In this embodiment, the position after the rectifier bridge is set as the sampling point B+. The position before the rectifier bridge can also be set as the sampling point B+, and other places can also be set, which cannot limit the protection scope of the present invention.

[0030] The working principle of this patent is described below in combination with the circuit schematic diagram:

[0031] In the normal working state, the power input outputs a high level after passing through the rectifier circuit BD1, and the high level of the sampling point B+ is stepped down through the seventh resistor R4 and added to the upper end of the first capacitor C1. The first capacitor C1 makes its voltage smooth and then adds it to the gate of the first switch tube Q1. The gate of the first switch tube Q1 receives the high level and is turned on. The voltage of the first resistor R6 is pulled down, causing the gate voltage of the second switch tube Q2 to drop. The second switch tube Q2 receives the low level and is turned on, so that the gate level of the third switch tube Q3 is pulled down, and the third switch tube Q3 is turned off. Since the third switch tube Q3 is in the turned-off state, the output capacitor E1 will not be discharged through the third switch tube Q3 at this time; and because the second switch tube Q2 is turned on, the fourth switch tube Q4 is also turned on; so the output is normal and the operation of the LED load is not affected.

[0032] Shutdown instant state: the rectifier circuit BD1 has no output, and the isolation device has an isolation function. The low level of the sampling point B+ makes the gate of the first switch tube Q1 low level through the seventh resistor R4. The gate of the first switch tube Q1 receives the low level and enters the shutdown state, and then the gate voltage of the second switch tube Q2 increases, so that the second switch tube Q2 is turned off, and then the gate voltage of the third switch tube Q3 increases, and the third switch tube Q3 is turned on. At this time, the output capacitor E1 is discharged through the third switch tube Q3. The discharge of the output capacitor E1 takes a certain time. Therefore, during the discharge of the output capacitor E1, regardless of whether the output capacitor E1 is completely discharged, because the second switch tube Q2 is turned off, the gate voltage of the fourth switch tube Q4 increases, and the gate of the fourth switch tube Q4 receives a high level and is also turned off, the LED load is disconnected, and the LED lamp is immediately extinguished, realizing the rapid shutdown function of the entire drive circuit.

[0033] The present invention provides a fast shutdown LED lamp control circuit that cuts off the output current. The fourth switch tube Q4 is set to directly control the power on of the LED load; the second switch tube Q2 directly controls the switch of the fourth switch tube Q4, so that the fourth switch tube Q4 directly controls its switch according to whether the circuit is powered on; the discharge circuit is not directly connected to the LED load, and when shutting down, regardless of whether the energy of the output capacitor E1 is fully discharged, the current of the LED load can be cut off, and the LED load does not need to wait for the discharge circuit to be fully discharged before turning off the LED lamp. Therefore, the LED lamp can be turned off quickly to achieve a fast shutdown function. The present invention has wide applicability and good compatibility with LED drive circuits.

[0034] The above is only a preferred specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any technician familiar with the technical field who uses this concept to make non-substantial changes to the present invention within the technical scope disclosed by the present invention shall be deemed to infringe the protection scope of the present invention.

Claims

1. A fast shutdown LED lamp control circuit for cutting off output current, characterized in that It includes a sampling circuit and a control module; the sampling circuit is connected to the control module, the control module is connected to the switch module, and the switch module is connected to the LED load; the sampling circuit receives a level signal and sends it to the control module, the control module controls the switch module to turn on or off, thereby controlling the LED load to be powered on or off; the two ends of the LED load are respectively connected to the switch module and the control module, the switch module is connected to the LED drive control device; the control module includes a first control device, a second control device and a third control device; the sampling circuit is connected to the first control device, the first control device is connected to the second control device, the second control device is connected to the third control device, and the third control device is connected to The switch module also includes a discharge circuit; one end of the discharge circuit is connected to the LED drive control device and the control device, and the other end of the discharge circuit is connected to the LED load; the first control device includes a first switch tube, a voltage regulator diode and a first resistor; the second control device includes a second switch tube, a second resistor and a third resistor; the third control device includes a third switch tube, a fourth resistor and a fifth resistor; the switch module includes a fourth switch tube and a sixth resistor; the gate of the first switch tube is connected to the sampling circuit, the source of the first switch tube is grounded, the drain of the first switch tube is connected to one end of the first resistor, and the other end of the first resistor is connected to the gate of the second switch tube and one end of the second resistor; The gate of the second switch tube is connected to one end of the second resistor connected to the first resistor, and the other end of the second resistor is connected to the positive electrode of the discharge circuit; the drain of the second switch tube is connected to the negative electrode of the LED load, the source of the second switch tube is connected to one end of the third resistor, and the other end of the third resistor is connected to the gate of the fourth switch tube; the gate of the third switch tube is connected to the source of the second switch tube and one end of the fourth resistor, and the other end of the fourth resistor is connected to the positive electrode of the discharge circuit; the source of the third switch tube is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the negative electrode of the LED load; the drain of the third switch tube is connected to the positive electrode of the discharge circuit; one end of the sixth resistor is connected to the gate of the fourth switch tube, and the other end of the sixth resistor is connected to the source of the fourth switch tube and the positive electrode of the discharge circuit; the drain of the fourth switch tube is connected to the positive electrode of the LED load; it also includes a rectifier circuit and an isolation device, the rectifier circuit is connected to the isolation device, and one end of the sampling circuit is connected between the rectifier circuit and the isolation device;The sampling circuit includes a seventh resistor, an eighth resistor and a first capacitor; one end of the seventh resistor is connected between the rectifier circuit and the isolation device, the other end of the seventh resistor is connected to one end of the eighth resistor, the other end of the eighth resistor is grounded, one end of the first capacitor is connected between the seventh resistor and the eighth resistor, the other end of the first capacitor is grounded, and the voltage stabilizing diode is connected in parallel to the two ends of the first capacitor; the discharge circuit is specifically a polar output capacitor; in the normal working state, the power input outputs a high level after passing through the rectifier circuit and is stepped down through the seventh resistor and added to the upper end of the first capacitor, the first capacitor makes its voltage smooth, and then adds it to the gate of the first switch tube to turn it on, and then the gate voltage of the second switch tube decreases, so that the second switch tube The first switch is turned on, and then the third switch is turned off. Because the third switch is turned off, the output capacitor will not discharge through the third switch at this time; because the second switch is turned on, the fourth switch is also turned on; so the normal output and the LED load operation are not affected; shutdown instant state: the rectifier circuit has no output, and the isolation device has an isolation function. The gate of the first switch is low through the seventh resistor, and the first switch enters the shutdown state. Then the gate voltage of the second switch increases, causing the second switch to turn off. Then the gate voltage of the third switch increases, and the third switch is turned on. At this time, the output capacitor discharges through the third switch. During the discharge of the output capacitor, because the second switch is turned off, the gate voltage of the fourth switch increases, and the fourth switch is also turned off, and the LED load is disconnected and shut down. ;

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