LED power supply constant power input control circuit

Abstract

The present invention discloses an LED power supply constant power input control circuit, which mainly includes: an LED driving power supply constant current control circuit, which is used to adjust the current value in the sampling resistor according to the grid voltage to ensure the output current constant current; an LED driving power supply constant power input control circuit, which is used to adjust the output current of the LED driving power supply constant current control circuit according to the LED lamp bead voltage to keep the input power constant. The LED power supply constant power input control circuit of the present invention can automatically adjust the current of the lamp bead according to the lamp bead voltage to maintain constant power input, which not only meets the user's demand for stable lighting, but also facilitates the advantages of production control by manufacturers.

Description

Technical Field

[0001] The invention relates to the field of constant power input control circuits, and in particular to a constant power input control circuit for an LED power supply. Background Art

[0002] Nowadays, there are more and more specifications and types of LED lamp beads, and their characteristics vary greatly. The number of lamp beads used by different customers also varies greatly. According to the standard of constant current source, the specifications of power supply are very diverse. For the same number of lamp beads, some lamp beads have very high voltage, and some lamp beads have very low voltage. According to the current constant current power supply scheme, the specifications of the power supply should be reduced, and the output current of the power supply should be adjusted with a potentiometer to adapt to different lamp bead voltages. However, the phenomenon of high temperature disconnection of the adjustment potentiometer contacts often occurs, which is unreliable. Summary of the invention

[0003] The purpose of the present invention is to propose a constant power input control circuit for an LED power supply to solve the above problems, so as to automatically adjust the current of the lamp beads according to the voltage of the lamp beads and maintain a constant power input, which not only meets the user's demand for stable lighting, but also facilitates the manufacturer's production control.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is: a constant power input control circuit for an LED power supply, mainly comprising:

[0005] The LED driving power supply constant current control circuit is used to adjust the current in the sampling resistor according to the grid voltage to ensure that the current in the LED is constant;

[0006] The LED driving power supply constant power input control circuit is used to adjust the current of the LED lamp beads in the LED driving power supply constant current circuit according to the LED lamp bead voltage, so that the input power remains constant.

[0007] Furthermore, the LED driving power constant power input circuit is arranged between the current sampling signal input terminal CS of the constant current control chip of the LED driving power constant current circuit and the control chip power supply voltage VCC.

[0008] Furthermore, the LED driving power supply constant power input control circuit includes:

[0009] Resistor R5, one end of the resistor R5 is connected to the positive electrode of the voltage zener diode Z1, the other end of the resistor R5 is the current sampling signal input terminal CS of the constant current control chip, the cathode of the voltage zener diode Z1 is connected to the emitter of the transistor Q2, the collector of the transistor Q2 is connected to one end of the resistor R7, and the control chip power supply voltage VCC is set between the collector of the transistor Q2 and one end of the resistor R7, the other end of the resistor R7 is respectively connected to the base of the transistor Q2 and the positive electrode of the electrolytic capacitor C3, and the negative electrode of the electrolytic capacitor C3 is connected to the primary ground GND.

[0010] Furthermore, the LED driving power supply constant current circuit includes:

[0011] A constant current control chip IC1, wherein the VCC terminal of the constant current control chip IC1 is connected to the control chip power supply voltage VCC, the GND terminal of the control chip IC1 is connected to the primary ground line GND, the current sampling signal input terminal CS of the constant current control chip IC1 is connected to one end of the resistor R1, the other end of the resistor R1 is respectively connected to one end of the resistor R2, one end of the resistor R3 and the S pole of the switch MOS tube, the other end of the resistor R2 is respectively connected to the drive signal output terminal GATE of the constant current control chip IC1 and the G pole of the switch MOS tube, the D pole of the switch MOS tube is connected to the pin 2 of the power transformer, the other end of the resistor R3 is connected to the primary ground line GND, the pin 1 of the power transformer is respectively connected to the high A DC voltage VDD and one end of a resistor R4 are connected, and the other end of the resistor R4 is respectively connected to a control chip power supply voltage VCC, a cathode of a diode D1 and a positive electrode of an electrolytic capacitor C2, the cathode of the electrolytic capacitor C2 is connected to a primary ground wire GND, the anode of the diode D1 is connected to pin 4 of the power transformer, pin 3 of the power transformer is connected to the primary ground wire GND, pin 10 of the power transformer is connected to the positive electrode of a secondary rectifier diode D2, an output filter capacitor C1 and a light emitting diode LED1 are respectively connected in parallel between the cathode of the secondary rectifier diode D2 and pin 6 of the power transformer, the cathode of the light emitting diode LED1 is connected to the secondary ground wire GNDD, and the anode of the light emitting diode LED1 is connected to a voltage output terminal VOUT.

[0012] Beneficial technical effects of the present invention:

[0013] The LED power supply constant power input control circuit mainly includes: an LED driving power supply constant current circuit, which is used to adjust the current in the sampling to ensure the constant current in the LED; an LED driving power supply constant power input control circuit, which is used to adjust the LED lamp bead current in the LED driving power supply level constant current circuit to keep the input power constant. The LED power supply constant power input control circuit can automatically adjust the lamp bead current according to the lamp bead voltage to maintain constant power input, which not only meets the user's demand for stable lighting, but also facilitates the manufacturer's production control.

[0014] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention.

[0015] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0017] Figure 1 This is a schematic diagram of a constant current control circuit for a primary constant current power supply of an LED in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of a constant power input control circuit for an LED driving power supply in an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of a constant current control circuit for a secondary constant current power supply of an LED in an embodiment of the present invention;

[0020] Figure 4 Schematic diagram of the secondary constant power input control circuit of the LED power supply in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0022] LED power supply constant power input control circuit, mainly includes:

[0023] The LED driving power supply constant current control circuit is used to adjust the current in the sampling resistor according to the grid voltage to ensure that the current in the LED is constant;

[0024] The LED driving power supply constant power input control circuit is used to adjust the current of the LED lamp beads in the primary constant current circuit of the LED driving power supply according to the lamp bead voltage, so that the input power remains constant.

[0025] The LED driving power constant power input control circuit is arranged between the current sampling signal input terminal CS of the constant current control chip of the LED driving power constant current circuit and the control chip power supply voltage VCC.

[0026] like Figure 2 As shown, the LED driving power supply constant power input control circuit includes:

[0027] Resistor R5, one end of the resistor R5 is connected to the positive electrode of the voltage zener diode Z1, the other end of the resistor R5 is the current sampling signal input terminal CS of the constant current control chip, the cathode of the voltage zener diode Z1 is connected to the emitter of the transistor Q2, the collector of the transistor Q2 is connected to one end of the resistor R7, and the control chip power supply voltage VCC is set between the collector of the transistor Q2 and one end of the resistor R7, the other end of the resistor R7 is respectively connected to the base of the transistor Q2 and the positive electrode of the electrolytic capacitor C3, and the negative electrode of the electrolytic capacitor C3 is connected to the primary ground GND.

[0028] like Figure 1 As shown, the LED driving power supply constant current control circuit includes:

[0029] The control chip IC1, the VCC terminal of the constant current control chip IC1 is connected to the control chip power supply voltage VCC, the GND terminal of the constant current control chip IC1 is connected to the primary ground line GND, the current sampling signal input terminal CS of the constant current control chip IC1 is connected to one end of the resistor R1, the other end of the resistor R1 is respectively connected to one end of the resistor R2, one end of the resistor R3 and the S pole of the switch MOS tube, the other end of the resistor R2 is respectively connected to the drive signal output terminal GATE of the control chip IC1 and the G pole of the switch MOS tube, the D pole of the switch MOS tube is connected to the pin 2 of the power transformer, the other end of the resistor R3 is connected to the primary ground line GND, the pin 1 of the power transformer is respectively connected to the high-voltage direct current after the mains rectification The current voltage VDD and one end of the resistor R4 are connected, and the other end of the resistor R4 is respectively connected to the constant current control chip power supply voltage VCC, the cathode of the diode D1 and the positive electrode of the electrolytic capacitor C2, the cathode of the electrolytic capacitor C2 is connected to the primary ground GND, the anode of the diode D1 is connected to the pin 4 of the power transformer, the pin 3 of the power transformer is connected to the primary ground GND, the pin 10 of the power transformer is connected to the positive electrode of the secondary rectifier diode D2, the cathode of the secondary rectifier diode D2 and the pin 6 of the power transformer are respectively connected in parallel with the output filter capacitor C1 and the light emitting diode LED1, the cathode of the light emitting diode LED1 is connected to the secondary ground GNDD, and the anode of the light emitting diode LED1 is connected to the voltage output terminal VOUT.

[0030] Figure 1 In the figure, IC1 is a constant current control chip, VCC is the power supply terminal of the chip, GND is the ground terminal, CS is the current sampling signal input terminal, GATE is the drive signal output terminal, and external MOS tubes and other switch tubes are connected. The function of the constant current control chip IC1 is to change the pulse signal frequency or pulse width output by the GATE terminal according to the current signal input by the CS terminal, so as to make the current in LED1 constant.

[0031] Figure 1In the figure, VDD is the high voltage DC voltage after the mains is rectified. T1 is the power transformer, D2 is the secondary rectifier diode, C1 is the output filter capacitor, and LED1 represents the LED light source. VDD charges VCC through R4. When the VCC voltage reaches the working voltage of IC1, IC1 works, and D1 starts to charge C2 connected to the VCC terminal to continuously power IC1. Q1 is a MOS tube, R3 is a current sampling resistor, and R2 is the discharge resistor of Q1.

[0032] exist Figure 1 On the basis of Figure 2 By using a medium circuit, constant power output can be achieved within a certain voltage range.

[0033] R7, C3, and Q2 form an active filter circuit, which outputs a stable DC voltage. After being divided by R5, Z1 and R1, R3, a stable DC bias voltage is provided to the CS terminal of the constant current control chip, reducing the current flowing through R3, thereby reducing the output current, that is, reducing the current in LED1. Figure 1 Pins 1, 3 and 6 of the transformer are the same terminals, and the VCC voltage is proportional to the voltage of LED1. When the voltage of LED1 is high, the VCC voltage is high, the bias voltage of the CS terminal is high, and the output current is reduced more. On the contrary, when the voltage of the light source LED1 is low, the VCC voltage is low, the bias voltage of the CS terminal is low, and the output current is reduced less. Reasonable configuration of R1, R5, and Z1 can achieve the purpose of constant power input.

[0034] Through experiments, the circuit of this application document was tested and it was found that the specific parameters of output voltage and input power are shown in Table 1:

[0035] Table 1 Output voltage and input power table

[0036]

[0037] From Table 1, we can see that the LED output voltage ranges from 21-42V, and the input power variation is less than +-5%, which is lower than the international standard of less than +-10% of the whole lamp power deviation. Figure 2 In the circuit shown, the output current is constant, so when the output voltage changes, the input power differs by about one time.

[0038] This solution makes up for the defect that the power of the whole lamp varies greatly due to the difference in current and voltage of different strings of lamp beads. Manufacturers can easily provide users with stable lighting power.

[0039] Figure 3This is a commonly used secondary constant current circuit for LED drive power supply. Operational amplifier U2A is a current error amplifier, LED2 is an LED light source, Rs is a current detection resistor, pin 3 of U2A is connected to a reference voltage Vz, and U1 is an isolation optocoupler.

[0040] Bundle Figure 2 CS access Figure 3 The second pin of U2A, Figure 2 and Figure 3 The ground wire is connected to Figure 2 The VCC terminal and Figure 3 The VOUT terminal is connected to Figure 4 As shown, constant power output can also be achieved.

[0041] At least the following beneficial effects can be achieved:

[0042] The LED power supply constant power input control circuit mainly includes: an LED driving power supply constant current control circuit, which is used to adjust the current in the sampling resistor according to the grid voltage to ensure that the current in the LED lamp bead is constant; an LED driving power supply constant power input control circuit, which is used to adjust the current of the LED lamp bead in the LED driving power supply constant current circuit according to the LED lamp bead voltage to keep the input power constant. The LED power supply constant power input control circuit can automatically adjust the current of the lamp bead according to the lamp bead voltage to maintain constant power input, which not only meets the user's demand for stable lighting, but also facilitates the manufacturer's production control.

[0043] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. LED power supply constant power input control circuit, characterized in that: Mainly include: The LED driving power supply constant current control circuit is used to adjust the current in the sampling resistor according to the grid voltage to ensure that the current in the LED is constant; The LED driving power supply constant power input control circuit is used to adjust the LED current in the LED driving power supply constant current control circuit according to the LED lamp bead voltage, so that the input power remains constant; The LED driving power supply constant power input control circuit is arranged between the current sampling signal input terminal CS of the constant current control chip of the LED driving power supply constant current control circuit and the control chip power supply voltage VCC; The LED driving power supply constant power input control circuit comprises: A resistor R5, one end of which is connected to the positive electrode of the voltage stabilizing diode Z1, the other end of which is the current sampling signal input terminal CS of the constant current control chip, the negative electrode of the voltage stabilizing diode Z1 is connected to the emitter of the transistor Q2, the collector of the transistor Q2 is connected to one end of the resistor R7, and a control chip power supply voltage VCC is arranged between the collector of the transistor Q2 and one end of the resistor R7, the other end of the resistor R7 is respectively connected to the base of the transistor Q2 and the positive electrode of the electrolytic capacitor C3, and the negative electrode of the electrolytic capacitor C3 is connected to the primary ground wire GND; LED drive power supply constant current control circuit includes: A constant current control chip IC1, wherein the VCC terminal of the constant current control chip IC1 is connected to the control chip power supply voltage VCC, the GND terminal of the control chip IC1 is connected to the primary ground line GND, the current sampling signal input terminal CS of the constant current control chip IC1 is connected to one end of the resistor R1, the other end of the resistor R1 is respectively connected to one end of the resistor R2, one end of the resistor R3 and the S pole of the switch MOS tube, the other end of the resistor R2 is respectively connected to the drive signal output terminal GATE of the constant current control chip IC1 and the G pole of the switch MOS tube, the D pole of the switch MOS tube is connected to the pin 2 of the power transformer, the other end of the resistor R3 is connected to the primary ground line GND, the pin 1 of the power transformer is respectively connected to the high A DC voltage VDD and one end of a resistor R4 are connected, and the other end of the resistor R4 is respectively connected to a control chip power supply voltage VCC, a cathode of a diode D1 and a positive electrode of an electrolytic capacitor C2, the cathode of the electrolytic capacitor C2 is connected to a primary ground wire GND, the anode of the diode D1 is connected to pin 4 of the power transformer, pin 3 of the power transformer is connected to the primary ground wire GND, pin 10 of the power transformer is connected to the positive electrode of a secondary rectifier diode D2, an output filter capacitor C1 and a light emitting diode LED1 are respectively connected in parallel between the cathode of the secondary rectifier diode D2 and pin 6 of the power transformer, the cathode of the light emitting diode LED1 is connected to the secondary ground wire GNDD, and the anode of the light emitting diode LED1 is connected to a voltage output terminal VOUT.

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