LED yellow light lamp tube, PCB and control circuit

Abstract

The utility model discloses an LED yellow light tube, a PCB and a control circuit, the control circuit comprises a rectification unit, a constant voltage unit, a filtering unit and a step-down constant current unit, the constant voltage unit comprises a step-up and step-down part; the input end of the rectification unit is used for being connected with an external power supply device, the output end of the rectification unit is connected with the input end of the buck-boost part, the output end of the buck-boost part is connected with the input end of the filtering unit, the output end of the filtering unit is connected with the input end of the buck constant current unit, and the input end of the buck constant current unit is connected with the output end of the rectification unit. The output end of the step-down constant current unit is used for being connected with a lighting piece. The constant voltage unit is used for providing stable output voltage for the filtering unit, and the voltage reduction constant current unit is used for providing stable output current for a lighting piece; according to the control circuit disclosed by the invention, the constant voltage unit is matched with the step-down constant current unit to realize constant voltage and constant current, so that the control circuit can provide constant working current for the lighting piece, and the requirement that the voltage drops over the A level is met.

Description

Technical Field

[0001] The utility model relates to the technical field of LED lamp tubes, in particular to an LED yellow lamp tube, a PCB board and a control circuit. Background Art

[0002] In view of the current market demand of chip manufacturers, covering traditional fluorescent lamp tubes with yellow sleeves is the mainstream choice for yellow lamp tubes. However, the yellow sleeves rely on imported materials, resulting in high costs and long stocking cycles. Moreover, covering the fluorescent lamp tubes with yellow sleeves will cause a low light transmittance, only about 50%. Further, compared with LED lamp tubes, fluorescent lamp tubes have the problems of shorter lifespan and lower luminous efficiency. Additionally, fluorescent lamp tubes require an external electronic ballast, while LED lamp tubes have an internal power supply. Therefore, compared with yellow fluorescent lamp tubes, LED yellow lamp tubes have more advantages in terms of cost performance.

[0003] In terms of the power supply performance of LED lamps, for general LED lamps, their power supply drop test only reaches grade B, that is, it allows the lamp to flicker when the voltage fluctuates within a test cycle. Therefore, the existing LED lamps are not suitable for scenarios where lamp flickering is not allowed, such as high-precision manufacturing and detection, security monitoring, and special working places, etc., and there is a problem of narrow application range.

[0004] It can be seen that the existing technology still needs to be improved. Summary of the Utility Model

[0005] In view of the above deficiencies of the existing technology, the purpose of the utility model is to provide a control circuit for an LED yellow lamp tube, which realizes constant voltage and constant current through the cooperation of a constant voltage unit and a step-down constant current unit, and can provide a constant working current for the lighting component, so as to meet the requirement of voltage drop over grade A.

[0006] To achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A control circuit for an LED yellow lamp tube includes a rectification unit, a constant voltage unit, a filtering unit and a step-down constant current unit. The constant voltage unit includes a buck-boost part. The input end of the rectification unit is used to connect to an external power supply device. The output end of the rectification unit is connected to the input end of the buck-boost part. The output end of the buck-boost part is connected to the input end of the filtering unit. The output end of the filtering unit is connected to the input end of the step-down constant current unit. The output end of the step-down constant current unit is used to connect to a lighting component. The constant voltage unit is used to provide a stable output voltage for the filtering unit, and the step-down constant current unit is used to provide a stable output current for the lighting component.

[0008] In the control circuit of the described LED yellow light tube, the constant voltage unit further includes a voltage dividing part. The buck-boost part includes a first control chip U1 and a first field effect transistor Q1. Pin 5 of the first control chip U1 is connected to the output end of the rectifying unit through the voltage dividing part. Pin 6 of the first control chip U1 is connected to the gate of the first field effect transistor Q1. The drain of the first field effect transistor Q1 is connected to the input end of the filtering unit. The source of the first field effect transistor Q1 is connected to pin 1 of the first control chip U1.

[0009] In the control circuit of the described LED yellow light tube, the constant voltage unit further includes a feedback part. One end of the feedback part is respectively connected to the source of the first field effect transistor Q1 and pin 1 of the first control chip U1, and the other end of the feedback part is grounded.

[0010] In the control circuit of the described LED yellow light tube, the feedback part includes a fourth resistor R4, an eleventh resistor R11, a fourteenth resistor R14, and a fifteenth resistor R15. One end of the fourth resistor R4 is connected to pin 1 of the first control chip U1. The other end of the fourth resistor R4 is respectively connected to one end of the eleventh resistor R11, the source of the first field effect transistor Q1, one end of the fourteenth resistor R14, and one end of the fifteenth resistor R15. The other end of the eleventh resistor R11 is connected to the gate of the first field effect transistor Q1. The other ends of the fourteenth resistor R14 and the fifteenth resistor R15 are respectively grounded.

[0011] In the control circuit of the described LED yellow light tube, the constant voltage unit further includes a protection part. One end of the protection part is connected to the voltage dividing part, and the other end of the protection part is connected to pin 4 of the first control chip U1.

[0012] In the control circuit of the described LED yellow light tube, the protection part includes a second reactor T2, a sixth diode D6, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. One end of the fifth resistor R5 is connected to the voltage dividing part. The other end of the fifth resistor R5 is connected to the negative electrode of the sixth diode D6. The positive electrode of the sixth diode D6 is respectively connected to one end of the sixth resistor R6 and one end of the second reactor T2. The other end of the sixth resistor R6 is respectively connected to one end of the seventh resistor R7 and pin 4 of the first control chip U1. The other ends of the second reactor T2 and the seventh resistor R7 are respectively grounded.

[0013] In the control circuit of the described LED yellow light tube, the buck constant current unit includes a signal input part, an adjustment part, and an output part. The input end of the signal input part is connected to the output end of the filtering unit. The output end of the signal input part is connected to the input end of the adjustment part. The output end of the adjustment part is connected to the input end of the output part. The output end of the output part is used to connect to the lighting component. The adjustment part is used to achieve buck constant current.

[0014] In the control circuit of the described LED yellow light tube, the adjustment part includes a second control chip U2. Pin 1, pin 2, and pin 3 of the second control chip U2 are respectively connected to the output end of the signal input part. Pin 5 and pin 6 of the second control chip U2 are respectively connected to the input end of the output part.

[0015] The present utility model also correspondingly provides a PCB board, on which the control circuit of the LED yellow light tube as described in any one of the above is printed.

[0016] The present utility model also correspondingly provides an LED yellow light tube, and the LED yellow light tube uses the control circuit of the LED yellow light tube as described in any one of the above to achieve working control.

[0017] Beneficial effects:

[0018] The present utility model provides a control circuit of an LED yellow light tube, which realizes constant voltage and constant current through the cooperation of a constant voltage unit and a buck constant current unit. When the input voltage provided by an external power supply device drops to the bottom within a cycle, through the effective transformation of the front-stage circuit, a constant output voltage is always maintained. At the same time, in a wide range of input voltages, the rear-stage circuit provides a stable current output for the lighting component through an accurate transformation mechanism, meeting the performance requirements when the voltage drop exceeds the A-level standard, improving the stability and reliability of the LED yellow light tube during operation, and increasing the applicable range of the LED yellow light tube. Brief description of the drawings

[0019] Figure 1 It is a circuit block diagram of the control circuit provided by the present utility model;

[0020] Figure 2 It is a circuit schematic diagram of the rectification unit, constant voltage unit, and filtering unit provided by the present utility model;

[0021] Figure 3 It is a circuit schematic diagram of the buck constant current unit provided by the present utility model.

[0022] Description of main component symbols: 1 - Rectification unit, 2 - Constant voltage unit, 21 - Voltage division part, 22 - Boost - buck part, 23 - Feedback part, 24 - Protection part, 3 - Filter unit, 4 - Step - down constant current unit, 41 - Signal input part, 42 - Adjustment part, 43 - Output part. Detailed implementation manners

[0023] The present utility model provides an LED yellow lamp tube, a PCB board and a control circuit. To make the purpose, technical solution and effect of the present utility model clearer and more definite, the following takes examples with reference to the attached drawings and further elaborates on the present utility model in detail.

[0024] In the description of the present utility model, it should be understood that terms such as "installation" and "connection" should be understood in a broad sense. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0025] Please refer to Figures 1 to 3 , the present utility model provides a control circuit for an LED yellow lamp tube, including a rectification unit 1, a constant voltage unit 2, a filter unit 3 and a step - down constant current unit 4. The constant voltage unit 2 includes a boost - buck part 22; the input end of the rectification unit 1 is used to connect to an external power supply device, the output end of the rectification unit 1 is connected to the input end of the boost - buck part 22, the output end of the boost - buck part 22 is connected to the input end of the filter unit 3, the output end of the filter unit 3 is connected to the input end of the step - down constant current unit 4, and the output end of the step - down constant current unit 4 is used to connect to a lighting component; the constant voltage unit 2 is used to provide a stable output voltage to the filter unit 3, and the step - down constant current unit 4 is used to provide a stable output current to the lighting component.

[0026] This application discloses an LED yellow lamp tube, which realizes constant voltage and constant current through the cooperation of the constant voltage unit 2 and the step - down constant current unit 4. When the input voltage provided by the external power supply device drops to the bottom within a cycle, through the effective transformation of the pre - stage circuit, a constant output voltage is always maintained. At the same time, in a wide range of input voltages, the post - stage circuit provides a stable current output for the lighting component through an accurate transformation mechanism, meeting the performance requirements when the voltage drop exceeds the A - level standard, improving the stability and reliability of the LED yellow lamp tube during operation, and increasing the applicable range of the LED yellow lamp tube.

[0027] In this embodiment, the external power supply device can be an AC power supply device, and its voltage input range can be 100 - 277VAC. The LED yellow lamp tube disclosed in this application can achieve constant current and constant voltage under a wide range of inputs, providing a stable working current and working voltage for the lighting component; the lighting component can be an LED lamp board, and a plurality of LED lamp beads are arranged on the LED lamp board.

[0028] Further, please refer to Figure 1 and Figure 2 The constant voltage unit 2 further includes a voltage dividing part 21. The buck-boost part 22 includes a first control chip U1 and a first field effect transistor Q1. The pin 5 of the first control chip U1 is connected to the output end of the rectifying unit 1 through the voltage dividing part 21. The pin 6 of the first control chip U1 is connected to the gate of the first field effect transistor Q1. The drain of the first field effect transistor Q1 is connected to the input end of the filtering unit 3. The source of the first field effect transistor Q1 is connected to the pin 1 of the first control chip U1.

[0029] In this embodiment, the model of the first control chip U1 is DIO8850B. The first control chip U1 is a single-stage, PFC flyback constant voltage type LED controller. The buck-boost part 22 constitutes a buck-boost circuit. The pulsating direct current rectified by the rectifying unit 1 will be input into the buck-boost circuit. The Buck-Boost circuit realizes the regulation of the output voltage by controlling the on and off of the first field effect transistor Q1.

[0030] In this embodiment, please refer to Figure 2 The voltage dividing part 21 includes a second resistor R2, a third resistor R3 and a third filtering capacitor EC3. One end of the second resistor R2 is connected to the output end of the rectifying unit 1. The other end of the second resistor R2 is connected to the positive electrode of the third filtering capacitor EC3 through the third resistor R3 and is connected to the pin 5 of the first control chip U1. The negative electrode of the third filtering capacitor EC3 is grounded.

[0031] In this embodiment, please refer to Figure 2, the rectifying unit 1 is used to convert alternating current into pulsating direct current. The rectifying unit 1 includes a first exciting coil L1, a varistor RV1, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first capacitor C1, a second inductor L2, a first resistor R1, and a second capacitor C2. One end of the first exciting coil L1 is used to connect to an external power supply device, the other end of the first exciting coil L1 is connected to the varistor RV1, one end of the varistor RV1 is connected to the positive electrode of the first diode D1 and the negative electrode of the second diode D2, the other end of the varistor RV1 is connected to the positive electrode of the third diode D3 and the negative electrode of the fourth diode D4, the negative electrodes of the first diode D1 and the third diode D3 are respectively connected to one end of the first capacitor C1, one end of the second inductor L2, and one end of the first resistor R1, the other end of the second inductor L2 and the other end of the first resistor R1 are respectively connected to one end of the second capacitor C2 and one end of the second resistor R2, the positive electrodes of the second diode D2, the fourth diode D4, the other end of the first capacitor C1, and the other end of the second capacitor C2 are respectively grounded.

[0032] In this embodiment, please refer to Figure 2 , the filtering unit 3 is used for smoothing the output to ensure the stability and safety of the output voltage. The filtering unit 3 includes a fifth diode D5, a first reactor T1, a second filtering capacitor EC2, a ninth resistor R9, a fourth capacitor C4, and a fifth capacitor C5. The drain of the first field effect transistor Q1 is respectively connected to one end of the first reactor T1 and the positive electrode of the fifth diode D5, one end of the second resistor R2 is respectively connected to the other end of the first reactor T1, the negative electrode of the second filtering capacitor EC2, the other end of the ninth resistor R9, the other end of the fourth capacitor C4, and one end of the fifth capacitor C5. The negative electrode of the fifth diode D5, the positive electrode of the second filtering capacitor EC2, and one end of the ninth resistor R9 are respectively connected to one end of the fourth capacitor C4. The fourth capacitor C4 is used to connect to a lighting component, and the other end of the fifth capacitor C5 is grounded.

[0033] Further, please refer to Figure 1 and Figure 2 , the constant voltage unit 2 further includes a feedback part 23. One end of the feedback part 23 is respectively connected to the source of the first field effect transistor Q1 and pin 1 of the first control chip U1, and the other end of the feedback part 23 is grounded.

[0034] In this embodiment, the feedback part 23 is used to detect the output voltage of the buck-boost part 22 to ensure a constant output voltage and improve the stability and reliability when the control circuit is working.

[0035] Further, please refer to Figure 2 , the feedback unit 23 includes a fourth resistor R4, an eleventh resistor R11, a fourteenth resistor R14, and a fifteenth resistor R15. One end of the fourth resistor R4 is connected to pin 1 of the first control chip U1, and the other end of the fourth resistor R4 is respectively connected to one end of the eleventh resistor R11, the source electrode of the first field-effect transistor Q1, one end of the fourteenth resistor R14, and one end of the fifteenth resistor R15. The other end of the eleventh resistor R11 is connected to the gate electrode of the first field-effect transistor Q1, and the other ends of the fourteenth resistor R14 and the fifteenth resistor R15 are respectively grounded.

[0036] Further, please refer to Figure 1 and Figure 2 , the constant voltage unit 2 further includes a protection unit 24. One end of the protection unit 24 is connected to the voltage dividing unit 21, and the other end of the protection unit 24 is connected to pin 4 of the first control chip U1.

[0037] In this embodiment, the protection unit 24 is used to keep the current of the first control chip U1 at zero when conducting, and reduce the current to zero before turning off, so as to realize the soft start of the first control chip U1 and reduce the conduction loss of the first control chip U1.

[0038] Further, please refer to Figure 2 , the protection unit 24 includes a second reactor T2, a sixth diode D6, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. One end of the fifth resistor R5 is connected to the voltage dividing unit 21, the other end of the fifth resistor R5 is connected to the cathode of the sixth diode D6, the anode of the sixth diode D6 is respectively connected to one end of the sixth resistor R6 and one end of the second reactor T2, the other end of the sixth resistor R6 is respectively connected to one end of the seventh resistor R7 and pin 4 of the first control chip U1, and the other ends of the second reactor T2 and the seventh resistor R7 are respectively grounded.

[0039] Further, please refer to Figure 1 and Figure 3 , the buck constant current unit 4 includes a signal input part 41, an adjustment part 42, and an output part 43. The input end of the signal input part 41 is connected to the output end of the filtering unit 3, the output end of the signal input part 41 is connected to the input end of the adjustment part 42, the output end of the adjustment part 42 is connected to the input end of the output part 43, and the output end of the output part 43 is used to connect to the lighting component; the adjustment part 42 is used to realize buck constant current.

[0040] Further, please refer to Figure 3, the adjustment unit 42 includes a second control chip U2. The pin 1, pin 2, and pin 3 of the second control chip U2 are respectively connected to the output end of the signal input unit 41, and the pin 5 and pin 6 of the second control chip U2 are respectively connected to the input end of the output unit 43.

[0041] In this embodiment, the model of the second control chip U2 is HI7000. HI7000 is a multi-functional average current type LED constant current driver with a simple peripheral circuit, applicable to the field of non-isolated high-power constant current LED driving in a wide voltage range. Its pin PWM supports PWM dimming with an ultra-small duty cycle, can respond to a pulse width as small as 60 ns, and its pin D is used to implement the analog dimming function; the second control chip U2 internally integrates an average current control algorithm, and the output current constant current accuracy ≤ ±3%, and the output current is less affected by the input and output voltages and the system inductor; the chip internally integrates loop compensation, the peripheral circuit is simple, and the system is more stable and reliable.

[0042] In this embodiment, please refer to Figure 3 , the signal input unit 41 is used to further filter the signal output by the filtering unit 3 and then feedback it to the PWM pin of the second control chip U2; the signal input unit 41 includes a fourth filter capacitor EC4, a third excitation coil L3, a fifth filter capacitor EC5, a sixteenth resistor R16, a seventeenth resistor R17, an eighth capacitor C8, and a ninth capacitor C9; the fourth filter capacitor EC4, the third excitation coil L3, and the fifth filter capacitor EC5 are connected in parallel; the positive pole of the fifth filter capacitor EC5 is respectively connected to one end of the sixteenth resistor R16 and one end of the seventeenth resistor R17, and the other end of the sixteenth resistor R16 and the other end of the seventeenth resistor R17 are respectively connected to one end of the eighth capacitor C8, one end of the ninth capacitor C9, and the pin 1, pin 2, and pin 3 of the second control chip U2; the negative pole of the fifth filter capacitor EC5, the other end of the eighth capacitor C8, and the other end of the ninth capacitor C9 are respectively grounded.

[0043] In this embodiment, please refer to Figure 3, the output unit 43 is used to smoothly adjust the output signal of the adjustment unit 42; the output unit 43 includes a seventh diode D7, a twenty-second resistor R22, a tenth capacitor C10, a sixth filter capacitor EC6, an eleventh capacitor C11, and a fourth exciting coil L4; the negative electrode of the seventh diode D7, one end of the twenty-second resistor R22, the positive electrode of the sixth filter capacitor EC6, and one end of the eleventh capacitor C11 are respectively connected to one end of the seventeenth resistor R17, the other end of the twenty-second resistor R22 is connected to one end of the tenth capacitor C10, the positive electrode of the seventh diode D7, the other end of the tenth capacitor C10, the negative electrode of the sixth filter capacitor EC6, and the other end of the eleventh capacitor C11 are respectively connected to the other end of the third reactor T3; the eleventh capacitor C11 is connected to one end of the fourth exciting coil L4, and the other end of the fourth exciting coil L4 is used to connect a lighting element.

[0044] The present utility model also correspondingly provides a PCB board, on which a control circuit of the LED yellow light tube as described in any one of the above is printed.

[0045] The present utility model also correspondingly provides an LED yellow light tube, and the operation control of the LED yellow light tube is realized by using the control circuit of the LED yellow light tube as described in any one of the above.

[0046] It can be understood that for those of ordinary skill in the art, equivalent substitutions or changes can be made according to the technical solution of the present utility model and its inventive concept, and all such changes or substitutions should fall within the protection scope of the present utility model.

Claims

1. A control circuit for an LED yellow light tube, characterized in that, It includes a rectifying unit, a constant voltage unit, a filtering unit, and a step-down constant current unit. The constant voltage unit includes a buck-boost section. The input end of the rectifying unit is used to connect to an external power supply device. The output end of the rectifying unit is connected to the input end of the buck-boost section. The output end of the buck-boost section is connected to the input end of the filtering unit. The output end of the filtering unit is connected to the input end of the step-down constant current unit. The output end of the step-down constant current unit is used to connect to a lighting component. The constant voltage unit is used to provide a stable output voltage to the filtering unit, and the step-down constant current unit is used to provide a stable output current to the lighting component.

2. The control circuit of an LED yellow light tube according to claim 1, characterized in that, The constant voltage unit further includes a voltage dividing section. The buck-boost section includes a first control chip U1 and a first field effect transistor Q1. The pin 5 of the first control chip U1 is connected to the output end of the rectifying unit through the voltage dividing section. The pin 6 of the first control chip U1 is connected to the gate of the first field effect transistor Q1. The drain of the first field effect transistor Q1 is connected to the input end of the filtering unit. The source of the first field effect transistor Q1 is connected to the pin 1 of the first control chip U1.

3. The control circuit of an LED yellow lamp tube according to claim 2, characterized in that, The constant voltage unit further includes a feedback section. One end of the feedback section is respectively connected to the source of the first field effect transistor Q1 and the pin 1 of the first control chip U1, and the other end of the feedback section is grounded.

4. The control circuit of an LED yellow lamp tube according to claim 3, wherein, The feedback section includes a fourth resistor R4, an eleventh resistor R11, a fourteenth resistor R14, and a fifteenth resistor R15. One end of the fourth resistor R4 is connected to the pin 1 of the first control chip U1. The other end of the fourth resistor R4 is respectively connected to one end of the eleventh resistor R11, the source of the first field effect transistor Q1, one end of the fourteenth resistor R14, and one end of the fifteenth resistor R15. The other end of the eleventh resistor R11 is connected to the gate of the first field effect transistor Q1. The other ends of the fourteenth resistor R14 and the fifteenth resistor R15 are respectively grounded.

5. The control circuit of an LED yellow lamp tube according to claim 2, characterized in that, The constant voltage unit further includes a protection section. One end of the protection section is connected to the voltage dividing section, and the other end of the protection section is connected to the pin 4 of the first control chip U1.

6. The control circuit of an LED yellow light tube according to claim 5, characterized in that, The protection section includes a second reactor T2, a sixth diode D6, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. One end of the fifth resistor R5 is connected to the voltage dividing section. The other end of the fifth resistor R5 is connected to the cathode of the sixth diode D6. The anode of the sixth diode D6 is respectively connected to one end of the sixth resistor R6 and one end of the second reactor T2. The other end of the sixth resistor R6 is respectively connected to one end of the seventh resistor R7 and the pin 4 of the first control chip U1. The other ends of the second reactor T2 and the seventh resistor R7 are respectively grounded.

7. The control circuit of an LED yellow light tube according to claim 1, characterized in that, The step-down constant current unit includes a signal input part, an adjustment part and an output part. The input end of the signal input part is connected to the output end of the filtering unit. The output end of the signal input part is connected to the input end of the adjustment part. The output end of the adjustment part is connected to the input end of the output part. The output end of the output part is used to connect to the lighting element; The adjustment part is used to achieve step-down constant current.

8. The control circuit of an LED yellow lamp tube according to claim 7, wherein The adjustment part includes a second control chip U2. Pin 1, pin 2 and pin 3 of the second control chip U2 are respectively connected to the output end of the signal input part. Pin 5 and pin 6 of the second control chip U2 are respectively connected to the input end of the output part.

9. A PCB board, characterized in that, The control circuit of the LED yellow light tube as described in any one of claims 1-8 is printed on the PCB board.

10. An LED yellow lamp tube, characterized in that, The LED yellow light tube adopts the control circuit of the LED yellow light tube as described in any one of claims 1-8 to realize working control.

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