CN216057574U - Multistage switch step-down circuit and LED lamps and lanterns - Google Patents
Multistage switch step-down circuit and LED lamps and lanterns Download PDFInfo
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- CN216057574U CN216057574U CN202122498233.7U CN202122498233U CN216057574U CN 216057574 U CN216057574 U CN 216057574U CN 202122498233 U CN202122498233 U CN 202122498233U CN 216057574 U CN216057574 U CN 216057574U
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Abstract
The utility model discloses a multi-stage switch voltage reduction circuit and an LED lamp. The multistage switching step-down circuit comprises a voltage detection circuit, a step-down constant current switching power supply circuit and a light source selection circuit, wherein the voltage detection circuit is used for detecting the input voltage of the step-down constant current switching power supply circuit, the light source selection circuit is used for selecting first to M groups of light sources in N groups of light sources to be connected in series according to the detection result of the voltage detection circuit and then connecting the first to M groups of light sources to the output end of the step-down constant current switching power supply circuit, N is more than or equal to 2, M is less than or equal to N, and when M is less than N, the working voltage of the M groups of light sources after being connected in series is less than or equal to the working voltage of the step-down constant current switching power supply circuit after M +1 groups of light sources are connected in series; when M is equal to N, the working voltage of the M groups of light sources after being connected in series is less than or equal to the input voltage of the voltage-reducing constant-current switching power supply circuit. The utility model meets the harmonic requirement, has high PF, no limit on output voltage, high efficiency, low output current, low requirement on device type selection and low circuit cost.
Description
Technical Field
The utility model belongs to the technical field of circuits, and particularly relates to a multi-stage switch voltage reduction circuit and an LED lamp.
Background
A light Emitting diode (led), which is a solid semiconductor device capable of converting electrical energy into visible light, can directly convert electricity into light. The LED lamp has been widely used in various places due to its advantages of high efficiency, energy saving, long life, environmental protection, etc.
When the LED lamp is used, an LED driving circuit is required to be adopted for driving. The voltage-reducing constant current switch power circuit is a relatively common LED drive circuit. The principle of the buck constant-current switching power supply circuit is that the output voltage is smaller than the input voltage, when the input voltage is smaller than the output voltage, the IC does not work, and the LED supplies power through the output electrolytic capacitor, so that no input current is generated, and harmonic waves are generated.
Disclosure of Invention
The present invention is directed to a multi-stage switching step-down circuit for solving the above-mentioned problems.
In order to achieve the purpose, the utility model adopts the technical scheme that: a multi-section switch voltage reduction circuit comprises a voltage detection circuit, a voltage reduction type constant current switch power supply circuit and a light source selection circuit, wherein the voltage detection circuit is used for detecting the input voltage of the voltage reduction type constant current switch power supply circuit, the light source selection circuit is used for selecting first to M groups of light sources in N groups of light sources to be connected in series according to the detection result of the voltage detection circuit and then connecting the first to M groups of light sources to the output end of the voltage reduction type constant current switch power supply circuit, N is more than or equal to 2, M is less than or equal to N, and when M is less than N, the working voltage of the voltage reduction type constant current switch power supply circuit after the M groups of light sources are connected in series is less than or equal to the working voltage of the voltage reduction type constant current switch power supply circuit after the M +1 groups of light sources are connected in series; when M is equal to N, the working voltage of the M groups of light sources after being connected in series is less than or equal to the input voltage of the voltage-reducing constant-current switching power supply circuit.
Furthermore, the light source selection circuit comprises a comparison circuit, a control logic circuit and a switch selection circuit, wherein the input end of the comparison circuit is connected with the output end of the voltage detection circuit, the output end of the comparison circuit is connected with the input end of the control logic circuit, and the control logic circuit is used for controlling the switch selection circuit to select M groups of light sources to be connected in series with the output end of the voltage reduction type constant current switch power supply circuit.
Furthermore, the switch selection circuit is composed of N switches, N groups of light sources are sequentially connected end to end, the positive end of the first group of light sources is the positive end of the N groups of light sources which are connected in series and is connected with the positive output end of the voltage reduction type constant current switch power supply circuit, and the N switches are respectively connected between the negative ends of the N groups of light sources and the negative output end of the voltage reduction type constant current switch power supply circuit.
Furthermore, the switch is realized by adopting a MOS tube.
Further, the operating voltage of the first group of light sources is 30-60V.
Furthermore, a power switch tube of the voltage reduction type constant current switch power supply circuit is shared with a switch selected by the control logic circuit.
Further, the comparison circuit is implemented by using a multi-way comparator.
Further, the voltage detection circuit comprises a resistance voltage division circuit and a capacitor C2, the resistance voltage division circuit is connected between the input ends of the voltage reduction type constant current switch power supply circuit, and the capacitor C2 is connected between the output end of the resistance voltage division circuit and the input negative end of the voltage reduction type constant current switch power supply circuit.
The utility model also provides an LED lamp which comprises the multi-section switch voltage reduction circuit and N groups of light sources, wherein the N groups of light sources are LED light sources.
The utility model has the beneficial technical effects that:
the utility model not only meets the harmonic requirement, has high PF, but also has no limitation on output voltage, higher driving efficiency, lower output current, low requirement on device type selection and low circuit cost.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a circuit block diagram of a first embodiment of the present invention;
FIG. 2 is a circuit diagram according to a first embodiment of the present invention;
fig. 3 is a circuit diagram of a light source selection circuit and a constant current control unit according to a first embodiment of the utility model.
Detailed Description
To further illustrate the various embodiments, the utility model provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the utility model and, together with the description, serve to explain the principles of the embodiments. Those skilled in the art will appreciate still other possible embodiments and advantages of the present invention with reference to these figures. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.
The utility model will now be further described with reference to the accompanying drawings and detailed description.
Example one
As shown in fig. 1-3, a multi-stage switching buck circuit includes a voltage detection circuit 11, a buck constant-current switching power supply circuit 12, and a light source selection circuit 13, where the voltage detection circuit 11 is configured to detect an input voltage of the buck constant-current switching power supply circuit 12, and the light source selection circuit 13 is configured to select first to M groups of light sources in N groups of light sources 14 to be connected in series according to a detection result of the voltage detection circuit 11, and then connect to an output terminal of the buck constant-current switching power supply circuit 12, and is driven by the buck constant-current switching power supply circuit 12, where N is greater than or equal to 2, and M is less than or equal to N, and when M is less than N, a working voltage after the M groups of light sources are connected in series is less than or equal to an input voltage of the buck constant-current switching power supply circuit 12 and a working voltage after the M +1 groups of light sources are connected in series; when M is equal to N, the working voltage of the M groups of light sources connected in series is less than or equal to the input voltage of the buck-type constant current switching power supply circuit 12.
In this embodiment, the light source is preferably an LED light source, but not limited thereto. N is 4, and the 4 groups of light sources are light source LED1, light source LED2, light source LED3 and light source LED4, respectively, but not limited thereto, and in some embodiments, the number of light sources may be set according to actual situations, such as N is 2, 3, 5, 6, and so on.
In this embodiment, the voltage detection circuit 11 includes a resistor voltage-dividing circuit and a capacitor C2, the resistor voltage-dividing circuit is connected between the input terminals of the buck-type constant-current switching power supply circuit 12, the first terminal of the capacitor C2 is connected to the output terminal of the resistor voltage-dividing circuit, and the second terminal is connected to the input negative terminal GND of the buck-type constant-current switching power supply circuit 12. More specifically, the resistance voltage dividing circuit includes resistors R4 and R5, a first end of the resistor R4 is connected to the positive input terminal Vbus of the buck-type constant current switching power supply circuit 12, a second end of the resistor R4 is connected in series with the resistor R5 and is connected to the negative input terminal GND of the buck-type constant current switching power supply circuit 21, and a node between the resistors R4 and R5 is an output end of the resistance voltage dividing circuit.
In this embodiment, the light source selection circuit 13 includes a comparison circuit, a control logic circuit U4 and a switch selection circuit, an input end of the comparison circuit is connected to an output end of the voltage detection circuit 11, an output end of the comparison circuit is connected to an input end of the control logic circuit U4, and the control logic circuit U4 is configured to control the switch selection circuit to select M groups of light sources to be connected in series to an output end of the buck-type constant current switch power supply circuit 12.
More specifically, in this embodiment, the switch selection circuit is composed of 4 switches Q1, Q2, Q3 and Q4, the light source LED1, the light source LED2, the light source LED3 and the light source LED4 are sequentially connected end to end in series, the positive terminal of the light source LED1 (the first group of light sources) is the positive terminal of the 4 groups of light sources after being connected in series, the positive terminal of the output of the buck-type constant current switch power circuit 12 is connected, and the switches Q1, Q2, Q3 and Q4 are respectively connected between the negative terminals of the light source LED1, the light source LED2, the light source LED3 and the light source LED4 and the negative terminal of the output of the buck-type constant current switch power circuit 12.
Preferably, in this embodiment, the switches Q1, Q2, Q3 and Q4 are implemented by MOS transistors, which have high sensitivity, large current tolerance and low loss, but are not limited thereto.
In this embodiment, the comparison circuit is implemented by using a multi-way comparator U2, an input end 3 of the multi-way comparator U2 is connected to an output end (a first end of a capacitor C2) of the voltage detection circuit 11, the multi-way comparator U2 is provided with three different reference voltages Vref1, Vref2 and Vref3, an output end of the multi-way comparator U2 is connected to an input end of the control logic circuit U4, and the control logic circuit U4 correspondingly controls the operation of the switches Q1, Q2, Q3 or Q4 according to a comparison result output by the multi-way comparator U2. The control logic circuit U4 can be implemented by a reference generator or a selection circuit, etc., which can be easily implemented by those skilled in the art and will not be described in detail. Of course, in some embodiments, the comparison circuit and the control logic circuit U4 may also be implemented by a single chip.
In this embodiment, the step-down constant current switch power supply circuit 12 includes an inductor T1, an output electrolytic capacitor EC1, a power switch tube, a sampling resistor R2, and a constant current control unit, preferably, in this embodiment, the power switch tube is shared with a switch selected by the control logic circuit U4, that is, the power switch tube is implemented by a switch Q1, a switch Q2, a switch Q3, or a switch Q4, the control logic circuit U4 correspondingly controls the switch Q1, a switch Q2, a switch Q3, or a switch Q4 to operate according to a comparison result output by the multi-path comparator U2, the switch is simultaneously controlled by the constant current control unit to implement constant current driving, the sampling resistor R2 is disposed between the switches Q1, Q2, a switch Q3, and a switch Q4 and an output negative terminal of the step-down constant current switch power supply circuit 12, and more specifically, see fig. 2 and 3. The power switch tube is shared with the switch selected by the control logic circuit U4, so that the number of switches is smaller, the circuit is simpler and more compact, and the cost is lower.
In this embodiment, the constant current control unit is implemented by using a comparator U3, a sampling terminal of the constant current control unit is connected to an output terminal of the sampling resistor R2, and the constant current control unit drives the corresponding switches Q1, Q2, Q3, or Q4 to operate through a control logic circuit U4, so as to implement constant current output. More specific constant current driving control can refer to the prior art, which is a well-established technology, and can be easily realized by a person skilled in the art, and is not described in detail. Of course, in some embodiments, the constant current control unit can also be implemented by using an existing constant current control chip.
In this embodiment, the buck constant-current switching power supply circuit 12 further includes a freewheeling diode D1, a negative terminal of the freewheeling diode D1 is connected to the negative terminal of the light source LED4, and a positive terminal of the freewheeling diode D1 is connected to an input terminal of the inductor T1. Of course, in some embodiments, the negative terminal of the freewheeling diode D1 may also be connected to the negative terminals of the light source LED1, LED2 and LED 3.
In some embodiments, the buck constant current switching power supply circuit 12 may also be implemented by other existing buck constant current switching power supply circuits.
Preferably, in this embodiment, the operating voltage of the light source LED1 is 30-60V, so that there is input current in the whole sinusoidal cycle, increasing the time for the LED light source to be lit, increasing the utilization of the LED light source and improving the power factor, so that the harmonics meet the requirements.
In this specific embodiment, the input circuit further includes an input circuit, an output terminal of the input circuit is connected to an input terminal of the buck-type constant current switching power supply circuit 12, the input circuit includes a rectification circuit DB and a filter circuit, the filter circuit includes an inductor L1, a resistor R1, and a capacitor C1, and the specific circuit connection is shown in fig. 2.
In this embodiment, the light source selection circuit 13 and the constant current control unit are integrated into a control module U1, so that the structure is more compact.
The working process is as follows:
the voltage detection circuit 11 detects the input voltage of the buck constant current switch power supply circuit 12 and transmits the input voltage to the multi-path comparator U2, when the working voltage of the light source LED1 < the input voltage of the buck constant current switch power supply circuit 12 < the working voltage of the series connection of the light source LED1 and the LED2, the detection voltage is smaller than a reference voltage Vref1, the control logic circuit U4 selects the switch Q1 to work, the light source LED1 is driven by a constant current, and when the switch Q1 is switched on, a conduction loop is as follows: vbus → inductor T1 → light source LED1 → switch Q1 → sampling resistor R2 → GND, and the turn-off loop is: vbus → inductor T1 → light source LED1 → light source LED2 → light source LED3 → light source LED4 → freewheeling diode D1 → Vbus.
When the working voltage of the series connection of the light source LED1 and the LED2 < the input voltage of the series connection of the light source LED1, the LED2 and the LED3 < the working voltage of the series connection of the light source LED 3938, the LED2 and the LED3, the detection voltage is between the reference voltages Vref1 and Vref2, the control logic circuit U4 selects the switch Q2 to work, the series connection of the light source LED1 and the LED2 is driven by constant current, and when the switch Q2 is turned on, the turn-on loop is as follows: vbus → inductor T1 → light source LED1 → light source LED2 → switch Q2 → sampling resistor R2 → GND, and the turn-off loop is: vbus → inductor T1 → light source LED1 → light source LED2 → light source LED3 → light source LED4 → freewheeling diode D1 → Vbus.
When the working voltage of the series connection of the light source LED1, the LED2 and the LED3 < the input voltage of the buck constant current switch power supply circuit 12 < the working voltage of the series connection of the light source LED1, the LED2, the LED3 and the LED4, the detection voltage is between the reference voltages Vref2 and Vref3, the control logic circuit U4 selects the switch Q3 to work, the series connection of the light source LED1, the LED2 and the LED3 is driven by constant current, and when the switch Q3 is turned on, the turn-on loop is as follows: vbus → inductor T1 → light source LED1 → light source LED2 → light source LED3 → switch Q3 → sampling resistor R2 → GND, and the turn-off loop is: vbus → inductor T1 → light source LED1 → light source LED2 → light source LED3 → light source LED4 → freewheeling diode D1 → Vbus.
When the working voltage of the light source LED1, LED2, LED3 and LED4 in series is < the input voltage of the buck constant current switching power supply circuit 12, the detection voltage is greater than Vref3 when the reference voltage is greater than Vref, the control logic circuit U4 selects the switch Q4 to work, the light source LED1, LED2, LED3 and LED4 in series are driven by constant current, and when the switch Q4 is turned on, the turn-on loop is: vbus → inductor T1 → light source LED1 → light source LED2 → light source LED3 → light source LED4 → switch Q4 → sampling resistor R2 → GND, and the turn-off circuit is: vbus → inductor T1 → light source LED1 → light source LED2 → light source LED3 → light source LED4 → freewheeling diode D1 → Vbus.
Example two
The utility model also provides an LED lamp which comprises the multi-stage switch voltage reduction circuit and N groups of light sources, wherein the N groups of light sources are LED light sources.
The utility model not only meets the harmonic requirement, has high PF, but also has no limitation on output voltage (the output voltage does not need to be fixedly set to be lower and can be adjusted along with the change of the input voltage), has higher driving efficiency, low output current, low requirement on device type selection and low circuit cost.
While the utility model has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the utility model as defined by the appended claims.
Claims (9)
1. A multistage switching step-down circuit which is characterized in that: the light source selection circuit is used for selecting first to M groups of light sources in N groups of light sources to be connected in series according to the detection result of the voltage detection circuit and then connecting the light sources to the output end of the voltage reduction type constant current switch power circuit, wherein N is more than or equal to 2, M is less than or equal to N, and when M is less than N, the working voltage of the M groups of light sources after being connected in series is less than or equal to the working voltage of the voltage reduction type constant current switch power circuit after being connected in series and is less than or equal to the working voltage of the M +1 groups of light sources after being connected in series; when M is equal to N, the working voltage of the M groups of light sources after being connected in series is less than or equal to the input voltage of the voltage-reducing constant-current switching power supply circuit.
2. The multi-stage switching buck circuit of claim 1, wherein: the light source selection circuit comprises a comparison circuit, a control logic circuit and a switch selection circuit, wherein the input end of the comparison circuit is connected with the output end of the voltage detection circuit, the output end of the comparison circuit is connected with the input end of the control logic circuit, and the control logic circuit is used for controlling the switch selection circuit to select M groups of light sources to be connected in series with the output end of the voltage reduction type constant current switch power supply circuit.
3. The multi-stage switching buck circuit of claim 2, wherein: the switch selection circuit is composed of N switches, N groups of light sources are sequentially connected end to end, the positive end of the first group of light sources is the positive end of the N groups of light sources which are connected in series and is connected with the positive output end of the voltage reduction type constant current switch power supply circuit, and the N switches are respectively connected between the negative ends of the N groups of light sources and the negative output end of the voltage reduction type constant current switch power supply circuit.
4. The multi-stage switching buck circuit of claim 3, wherein: the switch is realized by adopting an MOS tube.
5. The multi-stage switching buck circuit of claim 3, wherein: the working voltage of the first group of light sources is 30-60V.
6. The multi-segment switching buck circuit of claim 3 or 4, wherein: and a power switch tube of the voltage reduction type constant current switch power supply circuit is shared with a switch selected by the control logic circuit.
7. The multi-stage switching buck circuit of claim 2, wherein: the comparison circuit is realized by adopting a multi-path comparator.
8. The multi-stage switching buck circuit of claim 1, wherein: the voltage detection circuit comprises a resistance voltage division circuit and a capacitor C2, the resistance voltage division circuit is connected between the input ends of the voltage reduction type constant current switch power supply circuit, and the capacitor C2 is connected between the output end of the resistance voltage division circuit and the input negative end of the voltage reduction type constant current switch power supply circuit.
9. An LED lamp, characterized in that: comprising the multi-segmented switched buck circuit of any one of claims 1 to 8 and N groups of light sources, the N groups of light sources being LED light sources.
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| CN202122498233.7U CN216057574U (en) | 2021-10-18 | 2021-10-18 | Multistage switch step-down circuit and LED lamps and lanterns |
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| CN202122498233.7U CN216057574U (en) | 2021-10-18 | 2021-10-18 | Multistage switch step-down circuit and LED lamps and lanterns |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113811047A (en) * | 2021-10-18 | 2021-12-17 | 厦门阳光恩耐照明有限公司 | Multi-stage switch voltage reduction circuit, driving method thereof and LED lamp |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113811047A (en) * | 2021-10-18 | 2021-12-17 | 厦门阳光恩耐照明有限公司 | Multi-stage switch voltage reduction circuit, driving method thereof and LED lamp |
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