LED driver power supply with switch color temperature adjustment and its constant current controller

Abstract

The present invention discloses a switch color temperature adjusting LED driving power supply and a constant current controller thereof, the constant current controller comprises a ground terminal, an output ground terminal and a current bypass module connected between the ground terminal and the output ground terminal, wherein the ground terminal and the negative terminal of the input capacitor are grounded together, the output ground terminal is connected to the output ground terminal of the color temperature controller, and the current bypass module is used to use the energy on the input capacitor to power the color temperature controller during the state maintenance period after the input switch is turned off. By implementing the technical solution of the present invention, the volume and cost of the LED driving power supply are smaller.

Description

Technical Field

[0001] The invention relates to the field of LED lighting, and in particular to an LED driving power supply capable of adjusting color temperature by switching and a constant current controller thereof. Background Art

[0002] For the switch color temperature adjustment scheme, because it is necessary to maintain the state of the color temperature control chip within a period of time (usually about 5 seconds) when the input switch is disconnected, there must be enough energy to supply the color temperature control chip during this period. In the current color temperature control scheme, there must be a large capacitor to provide energy to the color temperature control chip during the state maintenance period. Usually, this capacitor appears in two forms: the first is an independent capacitor connected to the color temperature control chip. In this case, the color temperature control chip needs a special pin to connect to the capacitor, and when the input switch is closed (that is, when the light is normally on), a capacitor charging current is provided to fill the capacitor, so as to power the color temperature control chip when the input switch is disconnected; the second is to reuse the output capacitor of the LED driver power supply. In this case, the LED driver power supply must have an output capacitor. This solution may not be suitable for small-volume power supplies (such as light bulb solutions) or solutions with extremely high cost requirements, because usually no output capacitor is required in such applications.

[0003] The most widely used color temperature control solution is the non-isolation switch. Figure 1As shown, the LED driving power supply for adjusting the color temperature by switching mainly includes a constant current control circuit 113, a color temperature control circuit 114 and an LED lamp load 115, and the LED lamp load 115 generally includes two color temperature LED lamp groups 111 and 112. The constant current control circuit 113 is a non-isolated step-down constant current driving circuit, which is mainly composed of an AC rectifier circuit 101, a constant current control chip 104, an inductor 106, a freewheeling diode 105 and an output capacitor 107. The color temperature control circuit 114 is mainly composed of a color temperature control chip 110, a power supply resistor 109 and a detection resistor 108. The color temperature control chip 110 detects the switch moving point of the constant current control circuit 113 (i.e., the point where the D pin of the constant current control chip 104 is connected to the inductor 106) through the detection resistor 108, thereby judging the state of the input switch K. Because when the input switch K is closed, the constant current control circuit 113 works normally, and a waveform similar to a square wave appears at its switch moving point, and when the input switch K is disconnected, the constant current control circuit 113 stops working, and the square wave at its switch moving point disappears. The color temperature control chip 110 determines the state of the input switch K by detecting the waveform of the switch moving point, and then changes the switch state of the internal switch tube connected to the D1 and D2 pins of the color temperature control chip 110 accordingly, and finally realizes the change of color temperature. The two LEDs 111 and 112 with different color temperatures are used as loads, and their anodes are connected to the positive output of the constant current control circuit 113, and their cathodes are connected to the D1 and D2 pins of the color temperature control chip 110 respectively.

[0004] In addition, from Figure 1 It can also be seen that after the input switch K is disconnected, the constant current control circuit 113 stops, and thereafter the color temperature control circuit 114 can only be powered by the output capacitor 107, ensuring that the color temperature control chip 110 has enough energy to maintain the internal state of the chip for a period of time after the input switch K is disconnected. Therefore, the output capacitor 107 is necessary for the color temperature control circuit 114, because without this capacitor, the color temperature control circuit 114 will not be able to maintain the internal state during the period when the input switch K is disconnected. The output capacitor 107 not only affects the size of the LED driving power supply, but also increases the cost of the power supply. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a switch color temperature adjustable LED driving power supply and a constant current controller thereof in view of the defects of large volume and high cost in the prior art.

[0006] The technical solution adopted by the present invention to solve its technical problem is: construct a constant current controller, which is applied to an LED driving power supply with switch color temperature adjustment, wherein the LED driving power supply includes an input switch, an input capacitor, and a color temperature controller, and the constant current controller includes: a ground terminal, an output ground terminal, and a current bypass module connected between the ground terminal and the output ground terminal, wherein the ground terminal and the negative terminal of the input capacitor are grounded together, the output ground terminal is connected to the output ground terminal of the color temperature controller, and the current bypass module is used to use the energy on the input capacitor to power the color temperature controller during the state maintenance period after the input switch is turned off.

[0007] Preferably, the current bypass module comprises a first resistor connected between the ground terminal and the output ground terminal.

[0008] Preferably, the current bypass module also includes a first switch tube and a second resistor, wherein the first end of the second resistor is connected to the output ground terminal of the constant current controller, the second end of the second resistor is connected to the first end of the first switch tube, and the second end of the first switch tube is connected to the ground terminal of the constant current controller, and the first switch tube is turned on after the input switch is turned off and the voltage of the input capacitor is less than a second preset value, and is turned off when the input switch is closed.

[0009] Preferably, the constant current controller also includes a voltage detection module and a constant current control module, and the current bypass module also includes an RS trigger, wherein the voltage detection module outputs a reset signal to the RS trigger when the voltage of the input capacitor is greater than a first preset value, and the constant current control module is used to output a set signal to the RS trigger when the voltage of the input capacitor is less than a second preset value, and the output end of the RS trigger is connected to the control end of the first switch tube, and the second preset value is less than the first preset value.

[0010] Preferably, the constant current controller further includes a JFET tube, and a first end of the JFET tube is connected to the positive end of the input capacitor, and a second end of the JFET tube is connected to the input end of the voltage detection module.

[0011] Preferably, the voltage detection module includes a comparator and a pulse generating circuit, wherein the non-inverting input terminal of the comparator is connected to the second end of the JFET tube, the inverting input terminal of the comparator inputs a reference voltage, the output terminal of the comparator is connected to the input terminal of the pulse generating circuit, and the output terminal of the pulse generating circuit is connected to the reset terminal of the RS trigger.

[0012] The present invention also constructs an LED driving power supply with switch color temperature adjustment, comprising a constant current control circuit, a color temperature control circuit and an LED lamp load, wherein the LED lamp load comprises at least two LED lamp groups with different color temperatures, the constant current control circuit comprises an input switch and an input capacitor, and the color temperature control circuit comprises a color temperature controller, characterized in that the constant current control circuit also comprises the constant current controller described above.

[0013] Preferably, the constant current control circuit also includes an inductor and a freewheeling diode, wherein the first end of the inductor and the positive electrode of the freewheeling diode are respectively connected to the driving end of the constant current controller, the second end of the inductor is connected to the output ground end of the color temperature controller, and the negative electrode of the freewheeling diode is connected to the positive end of the input capacitor.

[0014] Preferably, the constant current control circuit also includes a rectifier bridge, a first input end of the rectifier bridge is connected to the first end of the AC power supply through the input switch, a second input end of the rectifier bridge is connected to the second end of the AC power supply, a positive output end of the rectifier bridge is connected to the positive end of the input capacitor, and a negative output end of the rectifier bridge is connected to the negative end of the input capacitor.

[0015] Preferably, the color temperature control circuit also includes a power supply resistor and a detection resistor, wherein the first end of the power supply resistor is connected to the positive end of the input capacitor, the second end of the power supply resistor is connected to the power supply end of the color temperature controller, and the detection resistor is connected to the driving end of the constant current controller and the clock end of the color temperature controller.

[0016] According to the technical solution of the present invention, since the output ground terminal of the constant current controller is connected to the output ground terminal of the color temperature controller, and a current bypass module is provided between the output ground terminal of the constant current controller and the ground terminal, the current bypass module can use the energy on the input capacitor to power the color temperature controller within a period of time after the input switch is turned off, so that the color temperature controller can realize the internal state holding function within a period of time after the input switch is turned off, and since there is no need to provide an output capacitor (such as Figure 1 The output capacitor 107 is shown, so the size and cost of the LED driving power supply are smaller. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0018] Figure 1 It is a circuit diagram of a LED driving power supply with a switch for adjusting color temperature in the prior art;

[0019] Figure 2 1 is a circuit diagram of a first embodiment of a LED driving power supply for adjusting color temperature by switching of the present invention;

[0020] Figure 3 1 is a circuit diagram of a constant current controller according to a first embodiment of the present invention;

[0021] Figure 4 is a circuit diagram of a first embodiment of a voltage detection module of the present invention;

[0022] Figure 5 is a circuit diagram of a first embodiment of a current bypass module of the present invention;

[0023] Figure 6 It is a working timing diagram of the LED driving power supply with switch color temperature adjustment of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Figure 2 1 is a circuit diagram of the first embodiment of the LED driving power supply with switch color temperature adjustment of the present invention, the LED driving power supply includes a constant current control circuit 212, a color temperature control circuit 213 and an LED lamp load 214, and the LED lamp load 214 includes two LED lamp groups 210 and 211 with different color temperatures. Among them, the constant current control circuit 212 is used to provide a constant current for the LED lamp groups 210 and 211; the color temperature control circuit 213 is used to control the color temperature of the LED lamp groups 210 and 211.

[0026] The constant current control circuit 212 includes an input switch K, a rectifier bridge 201, an input capacitor 202, a constant current controller 204, an inductor 206, and a freewheeling diode 205. The first input end of the rectifier bridge 201 is connected to the first end of the AC power supply 200 through the input switch K, the second input end of the rectifier bridge 201 is connected to the second end of the AC power supply 200, the positive output end of the rectifier bridge 201 is connected to the positive end of the input capacitor 202, the negative output end of the rectifier bridge 201 is connected to the negative end of the input capacitor 202, and the negative end of the input capacitor 202 and the ground end (GND) of the constant current controller 204 are grounded together. The power supply end (HV) of the constant current controller 204 and the negative electrode of the freewheeling diode 205 are respectively connected to the positive end (Vbk) of the input capacitor 202, and the positive electrode of the freewheeling diode 205 and the first end of the inductor 206 are respectively connected to the driving end (D) of the constant current controller 204. In addition, the constant current controller 204 includes a current bypass module inside, and the current bypass module is used to use the energy on the input capacitor 202 to power the color temperature controller during the state holding period after the input switch K is turned off.

[0027] The color temperature control circuit 213 includes a color temperature controller 209, a power supply resistor 208 and a detection resistor 207. The first end of the power supply resistor 208 is connected to the positive end (Vbk) of the input capacitor 202, the second end of the power supply resistor 208 is connected to the power supply end (VCC) of the color temperature controller 209, and the detection resistor 207 is connected between the clock end (CLK) of the color temperature controller 209 and the driving end (D) of the constant current controller 204. The output ground end (GND) of the color temperature controller 209 is respectively connected to the second end of the inductor 206 and the output ground end (VSD) of the constant current controller 204. In addition, the first driving end (D1) of the color temperature controller 209 is connected to the negative electrode of the LED lamp group 210, the second driving end (D2) of the color temperature controller 209 is connected to the negative electrode of the LED lamp group 211, and the positive electrode of the LED lamp group 210 and the positive electrode of the LED lamp group 211 are respectively connected to the positive end of the input capacitor 202.

[0028] In this embodiment, the driving end (D) of the constant current controller 204 is connected to the drain of the corresponding internal switch tube. When the switch tube inside the driving end (D) is turned on, the rectifier bridge 201 starts to supply power to the two LED light groups 210 and 211; when the switch tube inside the driving end (D) is turned off, the inductor 206 supplies power to the two LED light groups 210 and 211 through the freewheeling diode 205.

[0029] The color temperature controller 209 detects the signal of the switch point of the constant current control circuit 212 (i.e., the driving end of the constant current controller 204) through the detection resistor 207, thereby determining the state of the input switch K, and then controlling the states of the two LED lamp groups 210 and 211. Specifically, when the input switch K is closed, the constant current control circuit 212 works normally, and a waveform similar to a square wave appears at its switch point; when the input switch K is disconnected and the energy of the input capacitor 202 is also low, the constant current control circuit 212 stops working, and the square wave at its switch point disappears. Therefore, the color temperature controller 209 can be controlled by The state of the input switch K is determined by detecting the waveform of the switch moving point, and then the switch state of the internal switch tube connected to the two driving ends (D1, D2) of the color temperature controller 209 is changed accordingly to achieve the change of color temperature. For example, when the switch tube inside the first driving end (D1) is turned on, the LED light group 210 connected thereto is lit; when the switch tube inside the second driving end (D2) is turned on, the LED light group 211 connected thereto is lit; when the switch tubes inside the two driving ends (D1, D2) are both turned on, the two LED light groups 210, 211 will be lit at the same time. It should be noted here that this embodiment only shows two groups of LED light groups 210, 211. It should be understood that in actual applications, the LED load 214 can have more groups of LED light groups, and the number of driving ends of the color temperature controller 209 is also increased accordingly.

[0030] According to the technical solution of this embodiment, since the output ground terminal (VSD) of the constant current controller 204 is connected to the output ground terminal (GND) of the color temperature controller 209, and a current bypass module is provided between the output ground terminal (VSD) of the constant current controller 204 and the ground terminal (GND), the current bypass module can use the energy on the input capacitor 202 to power the color temperature controller 209 for a period of time after the input switch K is turned off, so that the color temperature controller 209 can realize the internal state holding function for a period of time after the input switch K is turned off, and since there is no need to provide an output capacitor (such as Figure 1 The output capacitor 107 is shown, so the size and cost of the LED driving power supply are smaller.

[0031] Figure 3 3 is a circuit diagram of a constant current controller embodiment of the present invention, in which the constant current controller 300 includes a current bypass module 301, a JFET tube 302, a voltage detection module 303, a constant current control module 304, a drive module 305 and a second switch tube 306. Moreover, the JFET tube 302 is a high-voltage device and is used to take power from the input capacitor 202 to power the constant current controller 204. The voltage detection module 303 is used to generate a pulse signal when the voltage of the input capacitor 202 is greater than a first preset value. The constant current control module 304 is used to generate a pulse signal when the voltage of the input capacitor 202 is less than a second preset value, and the second preset value is less than the first preset value. Among them, the first end of the JFET tube 302 is connected to the power supply end (HV) of the constant current controller 300, that is, the positive end of the input capacitor 202 is connected. The input end of the voltage detection module 303 is connected to the second end of the JFET tube 302, and the output end (vcc_en) of the voltage detection module 303 is connected to an input end of the current bypass module 301. An output terminal (SD) of the constant current control module 304 is connected to another input terminal of the current bypass module 301 .

[0032] Combination Figure 4 The voltage detection module includes a comparator 400 and a pulse generating circuit 401, wherein the non-inverting input terminal of the comparator 400 is connected to the second end of the JFET tube 302, the inverting input terminal of the comparator 400 inputs a reference voltage (Vref), the output terminal of the comparator 400 is connected to the input terminal of the pulse generating circuit 401, and the output terminal (vcc_cn) of the pulse generating circuit 401 outputs a pulse signal.

[0033] Combination Figure 5The current bypass module includes a first resistor 503, a second resistor 501, a first switch tube 502 and an RS trigger, wherein the first resistor 503 is connected between the ground terminal (GND) and the output ground terminal (VSD) of the constant current controller, the first end of the second resistor 501 is connected to the output ground terminal (VSD), the second end of the second resistor 501 is connected to the first end of the first switch tube 502, the second end of the first switch tube 502 is connected to the ground terminal (GND), the control end of the first switch tube 502 is connected to the output end of the RS trigger 500, the reset end of the RS trigger 500 is connected to the output end of the voltage detection module 303, and the set end of the RS trigger 500 is connected to the output end of the constant current control module 304. Therefore, the first switch tube 502 is turned on after the input switch K is turned off and the voltage of the input capacitor 202 is less than the second preset value, and is turned off when the input switch K is closed.

[0034] Combination Figure 2-6 Since the first resistor 503 connects the output ground of the color temperature controller 209 to the ground of the input capacitor 202, as long as the input capacitor 202 is charged, it is guaranteed that current flows through the color temperature controller 209, ensuring that the color temperature controller 209 will not lose power for a period of time after the input switch K is turned off. Therefore, even if the output capacitor is omitted, the color temperature controller 209 can still maintain power during the state holding period after the input switch K is turned off, thereby realizing the internal state preservation function.

[0035] Preferably, if system efficiency is taken into consideration, the resistance value of the first resistor 503 can be selected to be a larger resistance value.

[0036] In addition, when the constant current control module 304 stops working, it will output a shutdown signal (SD), which is input into the current bypass module 301 and connected to the set end of the RS trigger 500 in the current bypass module 301. Another input signal (vcc_en) of the current bypass module 301 is connected to the reset end of the RS trigger 500, and the output end of the RS trigger 500 is connected to the control gate of the first switch tube 502, and the signal is marked as gt_ctl.

[0037] Combination Figure 6 , if the current state of the input switch K is the on state, the first switch tube 502 is in the off state. At this time, there is only the first resistor 503 between the output ground terminal (VSD) of the constant current controller 204 and the ground of the input capacitor 202. The first resistor 503 can prevent the large voltage after rectification from being fully applied to the LED lamp group and the color temperature controller 209 to cause damage. When the first resistor 503 with a suitable resistance value is added, the output voltage of the constant current control module 304 is the voltage of the LED lamp group (the voltage difference between Vbk and VSD), that is, ΔV, during normal operation.

[0038] Combination Figure 6 If the current state of the input switch K is the off state, the voltage Vbk on the input capacitor 202 drops rapidly. When the voltage drops to a certain voltage, the constant current control module 304 stops working and outputs a shutdown signal SD. The signal causes the output terminal (gt_ctl) of the RS trigger 500 to become a high level, and the first switch tube 502 starts to turn on. At this time, in the current bypass module 301, in addition to the first resistor 503, a series branch consisting of a second resistor 501 and a first switch tube 502 is added between VSD and the ground of the input capacitor 202. Since the resistance value of the second resistor 501 is smaller than the resistance value of the first resistor 503, the anti-interference ability of the circuit can be increased.

[0039] Combination Figure 6 , when the input switch K is closed again after being disconnected for a period of time (Thold), the voltage Vbk on the input capacitor 202 rises rapidly. When the Vbk voltage (i.e., the HV voltage) exceeds the reference voltage Vref set inside the chip, the output end (vcc_en) of the voltage detection module 303 outputs a pulse signal, which resets the output end (gt_ctl) of the RS trigger 500 to "0", that is, turns off the first switch tube 502. At this time, there is only the first resistor 503 between VSD and the ground of the input capacitor 202. It should be noted here that the reason why the first switch tube 502 must be turned off when the voltage on the input capacitor 202 is large (greater than the first preset value) after the input switch K is closed is because this can avoid the damage of the color temperature controller 209 caused by the excessively high output voltage of the constant current control module 304.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A constant current controller, applied to an LED driving power supply for adjusting color temperature by switching, wherein the LED driving power supply comprises an input switch, an input capacitor, and a color temperature controller, and is characterized in that: The constant current controller includes: a ground terminal, an output ground terminal, and a current bypass module connected between the ground terminal and the output ground terminal, wherein the ground terminal and the negative terminal of the input capacitor are grounded together, the output ground terminal is connected to the output ground terminal of the color temperature controller, and the current bypass module is used to use the energy on the input capacitor to power the color temperature controller during the state maintenance period after the input switch is turned off.

2. The constant current controller according to claim 1, characterized in that: The current bypass module includes a first resistor connected between the ground terminal of the constant current controller and the output ground terminal of the constant current controller.

3. The constant current controller according to claim 2, characterized in that: The current bypass module also includes a first switch tube and a second resistor, wherein the first end of the second resistor is connected to the output ground terminal of the constant current controller, the second end of the second resistor is connected to the first end of the first switch tube, and the second end of the first switch tube is connected to the ground terminal of the constant current controller. The first switch tube is turned on after the input switch is turned off and the voltage of the input capacitor is less than a second preset value, and is turned off when the input switch is closed.

4. The constant current controller according to claim 3, characterized in that: The constant current controller also includes a voltage detection module and a constant current control module, and the current bypass module also includes an RS trigger, wherein the voltage detection module outputs a reset signal to the RS trigger when the voltage of the input capacitor is greater than a first preset value, and the constant current control module is used to output a set signal to the RS trigger when the voltage of the input capacitor is less than a second preset value, and the output end of the RS trigger is connected to the control end of the first switch tube, and the second preset value is less than the first preset value.

5. The constant current controller according to claim 4, characterized in that: The constant current controller also includes a JFET tube, and a first end of the JFET tube is connected to the positive end of the input capacitor, and a second end of the JFET tube is connected to the input end of the voltage detection module.

6. The constant current controller according to claim 5, characterized in that: The voltage detection module includes a comparator and a pulse generating circuit, wherein the non-inverting input terminal of the comparator is connected to the second end of the JFET tube, the inverting input terminal of the comparator inputs a reference voltage, the output terminal of the comparator is connected to the input terminal of the pulse generating circuit, and the output terminal of the pulse generating circuit is connected to the reset terminal of the RS trigger.

7. A switch color temperature adjustable LED driving power supply, comprising a constant current control circuit, a color temperature control circuit and an LED lamp load, wherein the LED lamp load comprises at least two LED lamp groups with different color temperatures, the constant current control circuit comprises an input switch and an input capacitor, and the color temperature control circuit comprises a color temperature controller, characterized in that: The constant current control circuit also includes a constant current controller as described in any one of claims 1-6.

8. The LED driving power supply with switch color temperature adjustment according to claim 7, characterized in that: The constant current control circuit also includes an inductor and a freewheeling diode, wherein the first end of the inductor and the positive electrode of the freewheeling diode are respectively connected to the driving end of the constant current controller, the second end of the inductor is connected to the output ground end of the color temperature controller, and the negative electrode of the freewheeling diode is connected to the positive end of the input capacitor.

9. The LED driving power supply with switch color temperature adjustment according to claim 8, characterized in that: The constant current control circuit also includes a rectifier bridge, a first input end of the rectifier bridge is connected to the first end of the AC power supply through the input switch, a second input end of the rectifier bridge is connected to the second end of the AC power supply, a positive output end of the rectifier bridge is connected to the positive end of the input capacitor, and a negative output end of the rectifier bridge is connected to the negative end of the input capacitor.

10. The LED driving power supply with switch color temperature adjustment according to claim 7, characterized in that: The color temperature control circuit also includes a power supply resistor and a detection resistor, wherein the first end of the power supply resistor is connected to the positive end of the input capacitor, the second end of the power supply resistor is connected to the power supply end of the color temperature controller, and the detection resistor is connected to the driving end of the constant current controller and the clock end of the color temperature controller.

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