Dimming control circuit and LED lamp

Abstract

The utility model provides a dimming control circuit and an LED lamp, the dimming control circuit comprises a constant voltage output circuit and an AC detection dimming circuit, the constant voltage output circuit comprises a rectifier, a power factor corrector and a power conversion isolator, the AC detection dimming circuit comprises a dimmer and an AC detection circuit, the AC detection circuit comprises a first resistor, a second resistor and a first capacitor, and the first resistor is connected with the second resistor. The light modulator comprises a light modulation unit and a field effect transistor. When the dimming control circuit is powered on, voltage exists at the detection end of the dimming unit, and the dimming unit works normally after detecting the voltage; when no alternating current is input into the dimming control circuit, the dimming unit still keeps working normally, at the moment, the voltage generated by the first capacitor completes a power-down action through the first resistor and the second resistor before the dimming unit is not powered down, then the dimming unit detects that the voltage of the detection end is zero, and the reset function is completed within the set time. Therefore, the scheme does not need to depend on an optocoupler, the cost is reduced, and the circuit space is saved.

Description

Technical Field

[0001] The present disclosure relates to the field of lighting technology, and in particular to a dimming control circuit and an LED lamp. Background Art

[0002] At present, the market demand for dimming products is increasing. Dimming products are widely used in many occasions such as hotels, offices, homes, shopping malls, etc. Dimming drivers play an indispensable and important role.

[0003] Currently, most isolated power supplies achieve this function by detecting voltage drops on the AC (alternating current) side of the transformer's primary side. Since the dimming module in most isolated power supplies is located on the transformer's secondary side, detecting the signal from the transformer's primary AC side often requires an optocoupler for isolation before the signal can be transmitted to the dimming module on the secondary side. This is reflected in existing patents CN101572972A and CN206993456U. While this approach allows the dimming module to implement AC detection, it is relatively expensive and relies on an optocoupler for isolation, making this circuit unsuitable for cost- or space-constrained applications.

[0004] Therefore, a circuit is needed that can enable the MCU to complete the reset function within a specified time after AC power failure without the need for optocoupler isolation, thereby solving the space limitation and cost issues. Utility Model Content

[0005] The purpose of the present disclosure is to overcome the shortcomings of the prior art and provide a dimming control circuit and LED lamp that can complete the reset function within a specified time after the AC end loses power and can solve the problems of space limitation and cost.

[0006] The purpose of this disclosure is achieved through the following technical solutions:

[0007] A dimming control circuit, comprising:

[0008] A constant voltage output circuit includes a rectifier, a power factor corrector, and a power conversion isolator, wherein the input end of the rectifier is used to connect to an AC power supply, the output end of the rectifier is electrically connected to the input end of the power conversion isolator through the power factor corrector, the positive output end of the power conversion isolator is used to connect to an LED load circuit, and the negative output end of the power conversion isolator is grounded;

[0009] An AC detection dimming circuit includes a dimmer and an AC detection circuit. The AC detection circuit includes a first resistor, a second resistor, and a first capacitor. The dimmer includes a dimming unit and a field-effect transistor. The first end of the first resistor is respectively connected to the positive output end of the power conversion isolator and the upper half end of the first capacitor. The second end of the first resistor is respectively connected to the first end of the second resistor and the detection end of the dimming unit. The second end of the second resistor is connected to the lower half end of the first capacitor. The lower half end of the first capacitor is grounded. The first end of the field-effect transistor is connected to the negative output end of the power conversion isolator. The second end of the field-effect transistor is used to connect to the LED load circuit. The control end of the field-effect transistor is connected to the pulse width modulation enable end of the dimming unit.

[0010] In one embodiment, the field effect transistor is an N-type MOS transistor.

[0011] In one embodiment, the AC detection circuit further includes a zener diode, a positive terminal of the zener diode is connected to the second end of the second resistor, and a negative terminal of the zener diode is connected to the pulse width modulation terminal of the dimming unit.

[0012] In one embodiment, the AC detection circuit further includes a first diode, wherein a positive end of the first diode is connected to the positive output end of the power conversion isolator, and a negative end of the first diode is respectively connected to the first end of the first resistor and the upper half end of the first capacitor.

[0013] In one embodiment, at least one of the first resistor and the second resistor is a variable resistor.

[0014] In one embodiment, the constant voltage output circuit further includes a second capacitor, wherein the upper half of the second capacitor is connected to the positive input terminal of the power conversion isolator, the lower half of the second capacitor is connected to the negative input terminal of the power conversion isolator, and the lower half of the second capacitor is grounded.

[0015] In one embodiment, the constant voltage output circuit further includes a third capacitor, wherein the upper half of the third capacitor is connected to the positive output terminal of the power conversion isolator, the lower half of the third capacitor is connected to the negative output terminal of the power conversion isolator, and the lower half of the third capacitor is grounded.

[0016] In one embodiment, the constant voltage output circuit further includes a second diode, a positive end of the second diode is connected to the first end of the first resistor, and a negative end of the second diode is connected to the upper half end of the third capacitor.

[0017] In one embodiment, the first capacitor is a high-frequency filter capacitor.

[0018] An LED lamp comprises the dimming control circuit described in any one of the above embodiments.

[0019] Compared with the prior art, the present disclosure has at least the following advantages:

[0020] When the dimming control circuit is powered, the output part of the power conversion isolator generates a voltage through the first capacitor. After the voltage is divided by the first resistor and the second resistor, a voltage is present at the detection end of the dimming unit. The dimming unit works normally after detecting the voltage. When there is no AC input to the dimming control circuit, the dimming unit still maintains normal operation. At this time, the voltage generated by the first capacitor completes the power-off action through the first resistor and the second resistor before the dimming unit is powered off. Subsequently, the dimming unit detects that the voltage at the detection end is 0 and completes the reset function within the specified time. Therefore, this solution completes AC detection and dimming unit reset through the output part of the power conversion isolator without relying on an optocoupler, thereby reducing costs and saving circuit space. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 1 is a schematic diagram of an overall circuit of a dimming control circuit in one embodiment;

[0023] Figure 2 for Figure 1 The circuit diagram of the dimming control circuit is shown.

[0024] Figure numerals: 10, dimming control circuit; 100, constant voltage output circuit; 200, AC detection dimming circuit; 210, dimmer; 220, AC detection circuit; BD1, rectifier; U1, power factor corrector; U2, dimming unit; T1, power conversion isolator; R1, first resistor; R2, second resistor; C1, second capacitor; C2, third capacitor; C3, first capacitor; D1, first diode; D2, second diode; ZD1, Zener diode; Q1, field effect transistor. DETAILED DESCRIPTION

[0025] To facilitate understanding of the present disclosure, a more comprehensive description of the present disclosure will be provided below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present disclosure. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure.

[0026] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure pertains. The terms used herein in the specification of this disclosure are intended only to describe specific embodiments and are not intended to limit this disclosure. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] In order to better understand the technical solutions and beneficial effects of the present disclosure, the present disclosure is further described in detail below with reference to specific embodiments:

[0029] See also Figures 1 to 2 , which is a dimming control circuit 10 according to an embodiment of the present invention, includes a constant voltage output circuit 100 and an AC detection dimming circuit 200 .

[0030] The constant voltage output circuit 100 includes a rectifier BD1, a power factor corrector U1 and a power conversion isolator T1. The input end of the rectifier BD1 is used to connect to an AC power supply. The output end of the rectifier BD1 is electrically connected to the input end of the power conversion isolator T1 through the power factor corrector U1. The positive output end of the power conversion isolator T1 is used to connect to an LED load circuit, and the negative output end of the power conversion isolator T1 is grounded. The AC detection dimming circuit 200 includes a dimmer 210 and an AC detection circuit 220. The AC detection circuit 220 includes a first resistor R1, a second resistor R2 and a first capacitor C3. The device 210 includes a dimming unit U2 and a field-effect transistor Q1. The first end of the first resistor R1 is respectively connected to the positive output terminal of the power conversion isolator T1 and the upper half of the first capacitor C3. The second end of the first resistor R1 is respectively connected to the first end of the second resistor R2 and the detection terminal of the dimming unit U2. The second end of the second resistor R2 is connected to the lower half of the first capacitor C3, and the lower half of the first capacitor C3 is grounded. The first end of the field-effect transistor Q1 is connected to the negative output terminal of the power conversion isolator T1. The second end of the field-effect transistor Q1 is used to connect to the LED load circuit. The control end of the field-effect transistor Q1 is connected to the pulse width modulation enable terminal of the dimming unit U2.

[0031] In this embodiment, when the dimming control circuit 10 is powered on, the output part of the power conversion isolator T1 generates a voltage through the first capacitor C3. After the voltage is divided by the first resistor R1 and the second resistor R2, a voltage is present at the detection end of the dimming unit U2. The dimming unit U2 operates normally after detecting the voltage. When there is no AC power input to the dimming control circuit 10, the dimming unit U2 still maintains normal operation. At this time, the voltage generated by the first capacitor C3 completes the power-off action through the first resistor R1 and the second resistor R2 before the dimming unit U2 is powered off. Subsequently, the dimming unit U2 detects that the voltage at the detection end is 0 and completes the reset function within the specified time. Therefore, this solution completes AC detection and resets the dimming unit U2 through the output part of the power conversion isolator T1 without relying on an optocoupler, thereby reducing costs and saving circuit space.

[0032] It can be understood that when the lamp is connected to AC power, the input AC power is rectified by the rectifier BD1, and then outputs the transformed voltage through the power factor corrector U1 and the power conversion isolator T1. At this time, the current at the positive output terminal of the power conversion isolator T1 passes through the first capacitor C3 to generate a voltage VO1+. After the voltage VO1+ is divided by the first resistor R1 and the second resistor R2, a voltage is generated at the detection terminal of the dimming unit U2. When the dimming unit U2 detects that there is a voltage at its detection terminal AC, it outputs a pulse width modulation signal from its pulse width modulation enable terminal PWM-Out, turns on the field effect transistor Q1, and performs The LED load circuit is energized to perform lighting operations. When there is no AC input, the dimming unit U2 needs to meet the dimming protocol, and the dimming module often has a maintenance time requirement. During a period of time when the power is disconnected, the dimming unit U2 still operates. The voltage VO1+ generated by the current passing through the first capacitor C3 will be powered down through the first resistor R1 and the second resistor R2 before the dimming unit U2 is powered down, causing the current voltage to become 0V. When the dimming unit U2 detects that there is no voltage at its detection terminal AC, it performs a reset operation, at which time the field effect transistor Q1 is turned off, and the LED load circuit is powered off. The first resistor R1 and the second resistor R2 are used for voltage division to provide a suitable detection voltage for the detection terminal AC pin of the dimming unit U2.

[0033] In this embodiment, the field effect transistor Q1 is an N-type MOS transistor, a first terminal of which is a source, a second terminal of which is a drain, and a control terminal of which is a gate.

[0034] like Figure 2As shown, in one embodiment, the AC detection circuit 220 further includes a Zener diode ZD1, with the positive terminal of the Zener diode ZD1 connected to the second terminal of the second resistor R2, and the negative terminal of the Zener diode ZD1 connected to the pulse width modulation terminal of the dimming unit U2. It will be understood that the Zener diode ZD1 is used to stabilize the voltage at the detection terminal of the dimmer 210, that is, the voltage at the detection terminal AC of the dimming unit U2. Specifically, the Zener diode ZD1 provides a stable detection voltage to protect the detection terminal AC pin of the dimming unit U2, preventing damage to the detection terminal AC pin due to large voltage fluctuations.

[0035] like Figure 2 As shown, in one embodiment, the AC detection circuit 220 further includes a first diode D1. The positive terminal of the first diode D1 is connected to the positive output terminal of the power conversion isolator T1, and the negative terminal of the first diode D1 is connected to the first terminal of the first resistor R1 and the upper half of the first capacitor C3, respectively. It will be understood that the first diode D1 is used to ensure that the output current of the power conversion isolator T1 flows unidirectionally to the AC detection circuit 220, preventing current backflow and damage to circuit components. Furthermore, the first diode D1 and the first capacitor C3 form the rectification and filtering circuit of the AC detection circuit 220, which is used to ensure unidirectional flow and filtering of the input signal, thereby reducing interference from unwanted signals.

[0036] In one embodiment, at least one of the first resistor R1 and the second resistor R2 is a variable resistor. In this embodiment, when one or both of the first resistor R1 and the second resistor R2 are variable resistors, the resistance ratio of the first resistor R1 to the second resistor R2 can be adjusted by adjusting the resistance value of the first resistor R1 and / or the second resistor R2, thereby adjusting the voltage value provided to the detection terminal AC of the dimming unit U2.

[0037] like Figure 1 or Figure 2As shown, in one embodiment, the constant voltage output circuit 100 further includes a second capacitor C1, the upper half of the second capacitor C1 being connected to the positive input terminal of the power conversion isolator T1, the lower half of the second capacitor C1 being connected to the negative input terminal of the power conversion isolator T1, and the lower half of the second capacitor C1 being grounded. In this embodiment, the output terminal of the rectifier BD1 is electrically connected to the input terminal of the power factor corrector U1, the output terminal of the power factor corrector U1 is electrically connected to the input terminal of the power conversion isolator T1, the upper half of the second capacitor C1 is respectively connected to the positive input terminal of the power conversion isolator T1 and the positive output terminal of the power factor corrector U1, and the lower half of the second capacitor C1 is respectively connected to the negative input terminal of the power conversion isolator T1 and the negative output terminal of the power factor corrector U1. It can be understood that the current after rectification and power factor correction will pass through the second capacitor C1 for signal filtering to stabilize the voltage at the input terminal of the power conversion isolator T1 and prevent voltage fluctuations from causing the voltage output to the LED load circuit to follow the fluctuations.

[0038] like Figure 1 As shown, in one embodiment, the constant voltage output circuit 100 further includes a third capacitor C2. The upper half of the third capacitor C2 is connected to the positive output terminal of the power conversion isolator T1, and the lower half of the third capacitor C2 is connected to the negative output terminal of the power conversion isolator T1. The lower half of the third capacitor C2 is grounded. It will be appreciated that after the input voltage is converted and output by the power conversion isolator T1, the output signal is filtered by the third capacitor C2 to stabilize the voltage output to the LED load circuit and prevent voltage fluctuations.

[0039] like Figure 2 As shown, in one embodiment, the constant voltage output circuit 100 further includes a second diode D2, with the positive terminal of the second diode D2 connected to the first terminal of the first resistor R1, and the negative terminal of the second diode D2 connected to the upper half of the third capacitor C2. It will be understood that the second diode D2 is used to rectify the output current, ensuring that the output current flows unidirectionally to the LED load circuit, and preventing the output current from flowing back and damaging circuit components. In this embodiment, the second diode D2 and the third capacitor C2 form a rectifier and filter circuit to ensure that the output current can be signal filtered by the third capacitor C2 and output unidirectionally to the LED load circuit.

[0040] In one embodiment, the first capacitor C3 is a high-frequency filter capacitor. It is understood that since the capacity of the first capacitor C3 is relatively small, generally in the nanofarad level, it can be used to filter high-frequency signals to ensure the normal operation of the entire circuit. At the same time, in the event of a power outage, the first capacitor C3 also makes it easier for the voltage VO1+ generated by the first diode D1 and the first capacitor C3 to complete the power-off operation through the first resistor R1 and the second resistor R2 when the dimming unit U2 is not powered off, thereby facilitating the reset function of the dimming unit U2.

[0041] The present disclosure further provides an LED lamp, comprising the dimming control circuit 10 of any of the above embodiments.

[0042] Compared with the prior art, the present disclosure has at least the following advantages:

[0043] When the dimming control circuit 10 is powered on, the output part of the power conversion isolator T1 generates a voltage through the first capacitor C3. After the voltage is divided by the first resistor R1 and the second resistor R2, a voltage is present at the detection end of the dimming unit U2. The dimming unit U2 operates normally after detecting the voltage. When there is no AC input to the dimming control circuit 10, the dimming unit U2 still maintains normal operation. At this time, the voltage generated by the first capacitor C3 completes the power-off action through the first resistor R1 and the second resistor R2 before the dimming unit U2 is powered off. Subsequently, the dimming unit U2 detects that the voltage at the detection end is 0 and completes the reset function within the specified time. Therefore, this solution completes AC detection and resets the dimming unit U2 through the output part of the power conversion isolator T1 without relying on an optocoupler, thereby reducing costs and saving circuit space.

[0044] The above-described embodiments merely represent several implementation methods of the present disclosure. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the disclosed patent. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the scope of the present disclosure, all of which fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the disclosed patent shall be determined by the appended claims.

Claims

1. A dimming control circuit, characterized in that: include: A constant voltage output circuit includes a rectifier, a power factor corrector, and a power conversion isolator, wherein the input end of the rectifier is used to connect to an AC power supply, the output end of the rectifier is electrically connected to the input end of the power conversion isolator through the power factor corrector, the positive output end of the power conversion isolator is used to connect to an LED load circuit, and the negative output end of the power conversion isolator is grounded; An AC detection dimming circuit includes a dimmer and an AC detection circuit. The AC detection circuit includes a first resistor, a second resistor, and a first capacitor. The dimmer includes a dimming unit and a field-effect transistor. The first end of the first resistor is respectively connected to the positive output end of the power conversion isolator and the upper half end of the first capacitor. The second end of the first resistor is respectively connected to the first end of the second resistor and the detection end of the dimming unit. The second end of the second resistor is connected to the lower half end of the first capacitor. The lower half end of the first capacitor is grounded. The first end of the field-effect transistor is connected to the negative output end of the power conversion isolator. The second end of the field-effect transistor is used to connect to the LED load circuit. The control end of the field-effect transistor is connected to the pulse width modulation enable end of the dimming unit.

2. The dimming control circuit according to claim 1, wherein: The field effect tube is an N-type MOS tube.

3. The dimming control circuit according to claim 1, wherein: The AC detection circuit further includes a voltage-stabilizing diode, a positive terminal of the voltage-stabilizing diode is connected to the second terminal of the second resistor, and a negative terminal of the voltage-stabilizing diode is connected to the pulse width modulation terminal of the dimming unit.

4. The dimming control circuit according to claim 1, wherein: The AC detection circuit further includes a first diode, wherein a positive end of the first diode is connected to the positive output end of the power conversion isolator, and a negative end of the first diode is respectively connected to the first end of the first resistor and the upper half end of the first capacitor.

5. The dimming control circuit according to claim 1, wherein: At least one of the first resistor and the second resistor is a variable resistor.

6. The dimming control circuit according to claim 1, wherein: The constant voltage output circuit also includes a second capacitor, the upper half of the second capacitor is connected to the positive input terminal of the power conversion isolator, the lower half of the second capacitor is connected to the negative input terminal of the power conversion isolator, and the lower half of the second capacitor is grounded.

7. The dimming control circuit according to claim 1, wherein: The constant voltage output circuit also includes a third capacitor, the upper half of the third capacitor is connected to the positive output terminal of the power conversion isolator, the lower half of the third capacitor is connected to the negative output terminal of the power conversion isolator, and the lower half of the third capacitor is grounded.

8. The dimming control circuit according to claim 7, wherein: The constant voltage output circuit further includes a second diode, a positive end of the second diode is connected to the first end of the first resistor, and a negative end of the second diode is connected to the upper half end of the third capacitor.

9. The dimming control circuit according to claim 1, wherein: The first capacitor is a high-frequency filter capacitor.

10. An LED lamp, characterized in that: The invention comprises the dimming control circuit according to any one of claims 1 to 9.

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