A power supply circuit and LED driving system using the same

Abstract

The present invention proposes a power supply circuit and an LED driving system using the same. The power supply circuit includes a linear conversion circuit, a first capacitor and a DC-DC conversion circuit. The AC input is rectified to obtain a first rectified voltage. The linear conversion circuit receives the first rectified voltage, and the output end is connected to the first capacitor. After the power supply circuit is started, the linear conversion circuit controls the first rectified voltage to charge the first capacitor during a time period when the first rectified voltage is near the valley position; the DC-DC conversion circuit receives the first capacitor voltage and performs power conversion to output the power supply voltage. In the LED driving system using the power supply circuit, the linear conversion circuit and at least part of the circuits in the DC-DC conversion circuit can be integrated with the LED driving circuit in the same chip or the same single base island package, so that the system is more concise. The power supply circuit of the present invention has high conversion efficiency, can realize single base island package integration, and is conducive to high frequency of the system, reduces the volume of energy storage devices, can improve integration, and reduce costs.

Description

Technical Field

[0001] The present invention relates to the field of electronic circuits, and in particular to a power supply circuit and an LED driving system using the same. Background Art

[0002] One of the existing intelligent lighting power supply solutions is the single-stage Buck power supply solution, such as Figure 1 As shown, the power supply part is the Buck circuit 2. The AC input of the AC power supply is rectified and filtered by the rectifier circuit 1 to output the rectified voltage VIN. The Buck circuit 2 converts the rectified voltage VIN into the power supply voltage Vo required by the wireless module 3. Figure 2 FIG2 shows a circuit structure of a Buck circuit 2. Another power supply scheme is a single-stage linear power supply scheme, such as Figure 3 As shown, the power supply part is a linear conversion circuit 5, the AC input output by the AC power supply is rectified by the rectifier circuit 1 and outputs the rectified voltage VIN, and the linear conversion circuit 5 converts the rectified voltage VIN into the power supply voltage Vo required by the wireless module 3. Figure 1 The single-stage Buck power supply scheme shown is different from the Figure 3 The single-stage linear power supply solution shown has the advantage of higher conversion efficiency, but its circuit structure is relatively complex, and it is difficult to further improve the integration level, which is not conducive to miniaturization and limits some application scenarios, such as the use of internal lamp drivers. The reasons why it is difficult to further improve the integration level are: 1. The input-output voltage difference is large. Under a certain minimum on-time requirement, it is difficult to further increase the switching frequency. The switching frequency is very low, which is not conducive to high frequency. The volume of energy storage devices such as inductor L1 will be relatively large; 2. Figure 2 As shown, the switch Q1 is on the high side and does not share a common ground with the output terminal. Due to packaging limitations, it is difficult to further integrate it with the subsequent LED driver circuit. On the other hand, the Buck circuit 2 in the single-stage Buck power supply solution generally needs to adopt the following Figure 2 In the dual-chip solution shown, the reference ground GND1 of the first chip 21 is the ground of the buck circuit 2, and the reference ground GND2 of the second chip 22 is the switch node SW. When the first chip 21 and the second chip 22 are packaged in the same package, a packaging frame with at least two base islands is required, which results in a high packaging cost. Figure 3 The single-stage linear power supply solution shown has the advantage of a very simple circuit structure, but it has low efficiency and is generally suitable for applications with output currents below 20mA, limiting its application in higher current scenarios. Therefore, it is necessary to propose an optimized power supply solution that can achieve high efficiency at a lower cost while further improving integration. Summary of the Invention

[0003] In view of this, an object of the present invention is to provide a power supply circuit and an LED driving system using the same, so as to solve the technical problem that the power supply circuit in the prior art cannot simultaneously meet the requirements of high conversion efficiency and high integration.

[0004] The technical solution of the present invention is to provide a power supply circuit for providing a power supply voltage to a load, wherein the power supply circuit includes a linear conversion circuit, a first capacitor and a DC-DC conversion circuit, and the AC input is rectified to obtain a first rectified voltage, wherein:

[0005] The linear conversion circuit receives the first rectified voltage, and an output end thereof is connected to the first capacitor. After the power supply circuit is started, the linear conversion circuit controls the first rectified voltage to charge the first capacitor during a time period when the first rectified voltage is near a valley position;

[0006] The DC-DC conversion circuit receives the first capacitor voltage and performs power conversion to output the supply voltage.

[0007] Optionally, the linear conversion circuit controls the first capacitor to start charging when the first rectified voltage sampling signal drops to a first threshold; or,

[0008] When the first rectified voltage sampling signal drops to a first threshold or the first capacitor voltage sampling signal is less than a third threshold, the first capacitor is controlled to start charging.

[0009] Optionally, the linear conversion circuit controls the first capacitor to cut off charging when the first capacitor voltage sampling signal rises to a second threshold;

[0010] Adjust the first threshold value according to the first rectified voltage sampling signal when charging of the first capacitor is cut off; or,

[0011] The first threshold is adjusted according to a first capacitor voltage sampling signal when the first capacitor starts to charge.

[0012] Optionally, the linear conversion circuit controls the first capacitor to stop charging when the first rectified voltage sampling signal rises to a fourth threshold;

[0013] Adjust the first threshold value according to a first capacitor voltage sampling signal when the first capacitor starts to charge; or,

[0014] The first threshold is adjusted according to a first capacitor voltage sampling signal when charging of the first capacitor is cut off.

[0015] Optionally, the linear conversion circuit

[0016] When the first threshold is greater than a first voltage, controlling the first threshold to decrease;

[0017] When the first threshold is less than a first voltage, controlling the first threshold to increase;

[0018] The first voltage is a first rectified voltage sampling signal when charging of the first capacitor is cut off.

[0019] Optionally, the DC-DC conversion circuit includes a switching circuit and a second control circuit, wherein the switching circuit includes a second switching tube located on the high side and a third switching tube located on the low side, and the second control circuit generates a second switching signal according to the output feedback signal of the DC-DC conversion circuit to control the conduction and shutdown of the second switching tube.

[0020] Optionally, the second control circuit and the second switch tube are integrated into the same chip or the same package using a single-island package frame.

[0021] Optionally, at least part of the linear conversion circuit is integrated into the same chip or the same package.

[0022] Optionally, the linear conversion circuit includes a first switch tube and a first control circuit, wherein:

[0023] The first power terminal of the first switch tube receives the first rectified voltage, and the second power terminal is connected to the first capacitor;

[0024] The first control circuit includes a first switch control circuit, which receives the first rectified voltage and the first capacitor voltage to generate a first switching signal. The first control circuit generates a first control signal based on the first switching signal. The control end of the first switching tube receives the first control signal, wherein the first control signal controls the conduction and shutdown of the first switching tube based on the first switching signal.

[0025] Optionally, the first switch control circuit includes:

[0026] an input voltage sampling circuit, sampling the first rectified voltage to output the first rectified voltage sampling signal and a first voltage, wherein the first voltage is the first rectified voltage sampling signal when the first switch tube starts to turn off;

[0027] a first threshold generating circuit, configured to output the first threshold, wherein the first threshold generating circuit adjusts the first threshold according to the first voltage;

[0028] a first comparison circuit, wherein a first input terminal receives the first threshold value, a second input terminal receives the first rectified voltage sampling signal, and generates a first conduction signal according to a comparison result of the first rectified voltage sampling signal and the first threshold value;

[0029] a first capacitor voltage sampling circuit, configured to sample the first capacitor voltage to output a first capacitor voltage sampling signal;

[0030] a second comparison circuit, wherein a first input terminal receives the first capacitor voltage sampling signal, a second input terminal receives the second threshold value, and generates a first shutdown signal according to a comparison result of the first capacitor voltage sampling signal and the second threshold value;

[0031] a first logic circuit, receiving the first on-signal and the first off-signal to output a first signal;

[0032] The first switch control circuit outputs the first signal as the first switch signal.

[0033] Optionally, the first switch control circuit further includes:

[0034] a third comparison circuit, wherein a first input terminal receives the third threshold value, a second input terminal receives the first capacitor voltage sampling signal, and generates a second signal according to a comparison result of the first capacitor voltage sampling signal and the third threshold value;

[0035] a first OR logic circuit, wherein a first input terminal receives the first signal, a second input terminal receives the second signal, and performs an OR logic operation on the first signal and the second signal;

[0036] The first switch control circuit outputs the output signal of the first OR logic circuit as the first switch signal.

[0037] Optionally, the first control circuit outputs the first switching signal as the first control signal.

[0038] Optionally, the first control circuit further includes a current limiting circuit for limiting the current when the first switching tube is turned on. The current limiting circuit samples the current of the first switching tube to obtain a first sampling signal, and outputs the first control signal based on the first sampling signal and the first switching signal.

[0039] Optionally, the DC-DC conversion circuit includes a switching circuit and a second control circuit, wherein the switching circuit includes a second switching tube located on the high side and a third switch located on the low side, and the second control circuit generates a second switching signal according to an output feedback signal of the DC-DC conversion circuit to control the on and off of the second switching tube;

[0040] The second control circuit, the second switch tube and the first switch tube are integrated into the same chip or the same package body using a single base island package frame.

[0041] Optionally, the DC-DC conversion circuit is a Buck circuit.

[0042] Optionally, the first capacitor voltage is 30-70V.

[0043] On the other hand, the present invention also provides an LED driving system, comprising a rectifier circuit, a wireless module, an LED driving circuit and the power supply circuit, wherein:

[0044] The rectifier circuit is connected to an AC input power supply, and outputs the first rectified voltage after rectifying the AC input;

[0045] The power supply circuit receives the first rectified voltage to output the power supply voltage, and the power supply voltage is used to power the wireless module;

[0046] The wireless module is used to output a dimming signal;

[0047] The LED driving circuit is used to provide a driving current to the LED load, and the LED driving circuit receives the dimming signal to adjust the magnitude of the driving current.

[0048] Optionally, the linear conversion circuit, at least part of the DC-DC conversion circuit, and at least part of the LED driving circuit are integrated into the same chip or the same package using a single island package frame.

[0049] Optionally, the second control circuit, the second switch tube, the first switch tube, and at least part of the LED driving circuit are integrated into the same chip or the same package using a single-island package frame.

[0050] Optionally, the rectifier circuit includes a rectifier bridge.

[0051] The rectifier bridge receives the AC input to output the first rectified voltage, and the input end of the LED driving circuit receives the first rectified voltage.

[0052] Optionally, the rectifier circuit includes a rectifier bridge and a unidirectional conducting device.

[0053] The rectifier bridge receives the AC input to output a second rectified voltage, and the input end of the LED driving circuit receives the second rectified voltage;

[0054] The anode of the unidirectional conductive device is connected to one end of the AC input power supply, the cathode of the unidirectional conductive device is connected to the first input end of the power supply circuit, and the second input end of the power supply circuit is grounded.

[0055] Optionally, the wireless module includes at least one of a Wi-Fi module, a Bluetooth module, and a ZigBee module.

[0056] Compared with the prior art, the power supply circuit of the present invention has the following advantages: conversion efficiency is close to or even higher than that of a single-stage Buck power supply solution; a single-island framework can be used for packaging and integration, resulting in lower packaging costs; it facilitates high-frequency system operation, and the volume of the energy storage device can be significantly reduced compared to a single-stage Buck power supply solution, thereby reducing costs, improving integration, and achieving miniaturization. Furthermore, in an LED driver system using this power supply circuit, the linear conversion circuit and at least part of the DC-DC conversion circuit can be integrated with the LED driver circuit on the same chip or within the same single-island package, resulting in a more concise system that can simultaneously meet the requirements of high conversion efficiency and high integration at a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a schematic diagram of the circuit structure of an LED driving system in the prior art;

[0058] Figure 2 for Figure 1 The circuit structure diagram of the Buck circuit in FIG;

[0059] Figure 3 Schematic diagram of the circuit structure of another LED driving system in the prior art;

[0060] Figure 4 Schematic diagram of the circuit structure of an LED driving system according to an embodiment of the present invention;

[0061] Figure 5 Schematic diagram of the circuit structure of a power supply circuit according to an embodiment of the present invention;

[0062] Figure 6 1 is a schematic diagram of the circuit structure of a first embodiment of the linear conversion circuit of the present invention;

[0063] Figure 7 2 is a schematic diagram of the circuit structure of a second embodiment of the linear conversion circuit of the present invention;

[0064] Figure 8 1 is a schematic diagram of the circuit structure of a third embodiment of the linear conversion circuit of the present invention;

[0065] Figure 9 The figure is a waveform diagram of a first rectified voltage sampling signal and a first capacitor voltage sampling signal according to an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments and covers any substitution, modification, equivalent method and solution made within the spirit and scope of the present invention.

[0067] In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without these detailed descriptions.

[0068] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are simplified and not to exact proportions, and are only used for the purpose of conveniently and clearly illustrating the embodiments of the present invention.

[0069] like Figure 4 As shown, an LED driving system according to an embodiment of the present invention includes a rectifier circuit 10, a power supply circuit 20, a wireless module 30, and an LED driving circuit 40. The rectifier circuit 10 is connected to an AC input power source, and outputs a first rectified voltage VIN after rectifying the AC input; the power supply circuit 20 receives the first rectified voltage VIN to output a power supply voltage Vo, which is used to power the wireless module 30; the wireless module 30 is used to output a dimming signal PWM; the LED driving circuit 40 is used to provide a driving current to the LED load, and the LED driving circuit 40 receives the dimming signal PWM to adjust the magnitude of the driving current. Specifically, in one embodiment, the rectifier circuit 10 includes a rectifier bridge 101, which receives an AC input to output a first rectified voltage VIN. The input end of the power supply circuit 20 and the input end of the LED driving circuit 40 both receive the first rectified voltage VIN. In this embodiment, the first rectified voltage VIN received at the input end of the power supply circuit 20 is a voltage obtained by full-wave rectification of the AC input. In another embodiment, the rectifier circuit includes a rectifier bridge 101 and a unidirectional conductive device, wherein the rectifier bridge 101 receives an AC input to output a second rectified voltage, and the input end of the LED driving circuit receives the second rectified voltage; the anode of the unidirectional conductive device is connected to one end of the AC input power supply, and the cathode is connected to the first input end of the power supply circuit 20, and the second input end of the power supply circuit 20 is grounded. For further example, the unidirectional conductive device can be Figure 4The first diode 102 or the second diode 103 is connected by a dotted line as shown in FIG. In this embodiment, the first rectified voltage VIN received at the input end of the power supply circuit 20 is a voltage obtained by half-wave rectification of the AC input. The power supply circuit 20 includes a linear conversion circuit 201, a first capacitor C01, and a DC-DC conversion circuit 202. The linear conversion circuit 201 receives the first rectified voltage VIN and has its output connected to the first capacitor C01. After the power supply circuit 20 is started, the linear conversion circuit 201 controls the first rectified voltage VIN to charge the first capacitor C01 during a period when the first rectified voltage VIN is near the bottom. The DC-DC conversion circuit 202 receives the first capacitor voltage VCC and performs power conversion to output the supply voltage Vo. The wireless module 30 may include at least one of a Wi-Fi module, a Bluetooth module, and a ZigBee module.

[0070] To improve conversion efficiency after the power supply circuit 20 is started, the linear conversion circuit 201 controls the first rectified voltage VIN to charge the first capacitor C01 during a period when the first rectified voltage VIN is near a valley position. In one embodiment, the linear conversion circuit 201 can control the first capacitor C01 to begin charging when the first rectified voltage sampling signal drops to a first threshold. In another embodiment, the linear conversion circuit can also control the first capacitor C01 to begin charging when the first rectified voltage sampling signal drops to the first threshold or when the first capacitor voltage sampling signal is less than a third threshold. In one embodiment, the linear conversion circuit 201 can control the first capacitor C01 to stop charging when the first capacitor voltage sampling signal rises to a second threshold. In another embodiment, the linear conversion circuit can control the first capacitor C01 to stop charging when the first rectified voltage sampling signal rises to a fourth threshold. Furthermore, the first threshold can be dynamically adjusted to achieve more efficient charging of the first capacitor C01, further improving the conversion efficiency of the linear conversion circuit 201. For example, in an embodiment of the linear conversion circuit that controls the first capacitor to be charged and cut off when the first capacitor voltage sampling signal rises to a second threshold, the first threshold can be adjusted according to the first rectified voltage sampling signal when the first capacitor C01 is charged and cut off. Specifically, when the first threshold is greater than the first voltage, the first threshold can be controlled to decrease; when the first threshold is less than the first voltage, the first threshold can be controlled to increase; wherein, the first voltage is the first rectified voltage sampling signal when the first capacitor is charged and cut off.

[0071] In one embodiment, the first capacitor voltage VCC is 30-70V. Preferably, the first capacitor voltage VCC is 40-60V. In one embodiment, the DC-DC conversion circuit is a Buck circuit, which performs power conversion on the first capacitor voltage VCC to output a power supply voltage Vo of, for example, 5V or 3.3V. Figure 1 Compared with the Buck circuit 2 in the prior art shown in FIG, the maximum input voltage of the DC-DC conversion circuit 202 in the power supply circuit 20 of the present invention is greatly reduced. Therefore, the DC-DC conversion circuit 202 does not need to adopt a high-cost high-voltage manufacturing process and can be prepared using a lower-cost manufacturing process. On the other hand, the maximum input-output voltage difference of the DC-DC conversion circuit 202 is also greatly reduced, and the switching frequency and conversion efficiency of the DC-DC conversion circuit 202 can be improved. The volume of the energy storage device can be greatly reduced, thereby reducing costs, improving integration, and achieving miniaturization; and single-island packaging can be achieved, reducing packaging costs. In addition, compared with Figure 3 Compared to the linear conversion circuit 5 of the prior art shown, the linear conversion circuit 201 of the present invention reduces the input-output voltage difference, and the first rectified voltage VIN charges the first capacitor C01 during the period when the first rectified voltage VIN is near its valley, thereby improving conversion efficiency. In addition, if the linear conversion circuit 201 adopts a method of dynamically adjusting the first threshold, the conversion efficiency can be further improved. Combining the high conversion efficiency of the DC-DC conversion circuit 202 of the present invention with the relatively high conversion efficiency of the linear conversion circuit 201, the overall conversion efficiency of the power supply circuit 20 can be close to or even higher than that of the single-stage Buck power supply solution of the prior art.

[0072] refer to Figure 5 In one embodiment, the linear conversion circuit 201 includes a first switch tube Q01 and a first control circuit 2011, wherein the first power terminal of the first switch tube Q01 receives a first rectified voltage VIN, and the second power terminal is connected to a first capacitor C01; the first control circuit 2011 receives the first rectified voltage VIN and the first capacitor voltage VCC to generate a first control signal gate1, and the control terminal of the first switch tube Q01 receives the first control signal gate1. The DC-DC conversion circuit 202 includes a switching circuit and a second control circuit 2021, wherein the switching circuit includes a second switch tube Q02 located on the high side, a third switch tube Q03 located on the low side, a first inductor L01, and a second capacitor C02. The second control circuit 2021 generates a second switching signal gate2 based on the output feedback signal FB of the DC-DC conversion circuit 202 to control the conduction and shutdown of the second switch tube Q02. In one embodiment, the third switch tube Q03 can be as follows Figure 5The synchronous rectifier MOS transistor shown in FIG2 can also be a freewheeling diode in another embodiment. In one embodiment, the second control circuit 2021 and the second switch transistor Q02 in the DC-DC converter circuit 202 can be integrated into the same chip. In another embodiment, the second control circuit 2021 and the second switch transistor Q02 can also be integrated on different chips and then packaged in the same package, wherein a single-island package frame can be used for the package. When the third switch transistor Q03 is a synchronous rectifier MOS transistor, in one embodiment, the second control circuit 2021, the second switch transistor Q02, and the third switch transistor Q03 can be integrated into the same chip. In another embodiment, the second control circuit 2021, the second switch transistor Q02, and the third switch transistor Q03 can also be integrated on different chips and then packaged in the same package, wherein a single-island package frame can be used for the package. When the third switch transistor Q03 is a freewheeling diode, in one embodiment, the second control circuit 2021 and the second switch transistor Q02 can be integrated into the same chip and then packaged together with the third switch transistor Q03 in the same package, wherein a single-island package frame can be used for the packaging. In another embodiment, the second control circuit 2021 and the second switch transistor Q02 can be integrated onto separate chips and then packaged together with the third switch transistor Q03 in the same package, wherein a single-island package frame can be used for the packaging. In addition, all or part of the linear converter circuit 201 can also be integrated with at least part of the DC-DC converter circuit 202. For example, in one embodiment, the second control circuit 2021, the second switch transistor Q02, and the first switch transistor Q01 can be integrated into the same chip. In another embodiment, the second control circuit 2021, the second switch transistor Q02, and the first switch transistor Q01 can also be integrated onto separate chips and then packaged together in the same package, wherein a single-island package frame can be used for the packaging. It is understandable that in some other embodiments, the entire linear conversion circuit 201 and at least a portion of the DC-DC conversion circuit 202 may be integrated, that is, the first control circuit 2011 and the first switch tube Q01 and at least a portion of the DC-DC conversion circuit 202 may be integrated, and examples are not given here one by one. Figure 4 and Figure 5In the LED driver system of the present invention, the linear conversion circuit 201, at least a portion of the DC-DC conversion circuit 202, and at least a portion of the LED driver circuit 40 can be integrated into the same chip, or integrated onto different chips and then packaged together in the same package, wherein a single-island package frame can be used for the packaging. For example, in one embodiment, the second control circuit 2021, the second switch transistor Q02, and at least a portion of the LED driver circuit can be integrated into the same chip; in another embodiment, the second control circuit 2021, the second switch transistor Q02, and at least a portion of the LED driver circuit can be integrated onto different chips and then packaged together in the same package, wherein a single-island package frame can be used for the packaging. In one embodiment, the second control circuit 2021, the second switch transistor Q02, the first switch transistor Q01, and at least a portion of the LED driver circuit can be integrated into the same chip. In another embodiment, the second control circuit 2021, the second switch transistor Q02, the first switch transistor Q01, and at least a portion of the LED driver circuit can be integrated onto separate chips and then packaged together within the same package. A single-island package frame can be used for packaging. Using a single-island package frame can reduce packaging costs. The LED driver system of the present invention is more concise and can simultaneously meet the requirements of high conversion efficiency and high integration at a lower cost.

[0073] Below is Figure 6-Figure 8 The three embodiments of the linear conversion circuit are shown as examples, and combined with Figure 9 , the circuit structure and working principle of the linear conversion circuit 201 are introduced. Figure 6-Figure 8 In the embodiment, the first control circuit 2011 in the linear conversion circuit 201 includes a first switch control circuit 20111, which receives a first rectified voltage VIN and a first capacitor voltage VCC to generate a first switch signal, and the first control circuit 2011 generates a first control signal gate1 according to the first switch signal.

[0074] Figure 6The circuit structure diagram of the first embodiment of the linear conversion circuit is shown. In this embodiment, the first control circuit 2011 includes: a first switch control circuit 20111, and the first switch control circuit 20111 includes: an input voltage sampling circuit 201111 sampling the first rectified voltage VIN to output a first rectified voltage sampling signal VIN′ and a first voltage V1, wherein the first voltage V1 is the first rectified voltage sampling signal when the charging of the first capacitor is cut off. In this embodiment, the first voltage V1 corresponds to the first rectified voltage sampling signal when the first switch tube Q01 starts to turn off; a first threshold generating circuit 201112 is used to output a first threshold value Vref1, and the first threshold generating circuit 201112 adjusts the first threshold value Vref1 according to the first voltage V1; a first input terminal of the first comparison circuit U01 receives the first threshold value Vref1, and a second input terminal receives the first rectified voltage sampling signal VIN′, and compares the first rectified voltage sampling signal VIN′ with the first threshold value Vref1. The result generates a first on-signal S1_ON for controlling the on-state of the first switch transistor Q01. The first capacitor voltage sampling circuit 201113 samples the first capacitor voltage VCC to output a first capacitor voltage sampling signal VCC′. The second comparison circuit U02 receives the first capacitor voltage sampling signal VCC′ at its first input terminal and a second threshold value Vref2 at its second input terminal. Based on the comparison result of the first capacitor voltage sampling signal VCC′ and the second threshold value Vref2, the circuit generates a first off-signal S1_OFF for controlling the off-state of the first switch transistor Q01. The first logic circuit 201114 receives the first on-signal S1_ON and the first off-signal S1_OFF to output a first signal S1. When the first threshold value Vref1 is greater than the first voltage V1, the first threshold generation circuit 201112 controls the first threshold value Vref1 to decrease; when the first threshold value Vref1 is less than the first voltage V1, the first threshold generation circuit 201112 controls the first threshold value Vref1 to increase. In one embodiment, the input voltage sampling circuit 201111 can generate the first voltage V1 based on the first off-signal S1_OFF. The first switch control circuit 20111 outputs the first signal S1 as the first switch signal, and the first control circuit 2011 outputs the first switch signal as the first control signal gate1.

[0075] refer to Figure 6 and Figure 9 In this embodiment, when the first rectified voltage sampling signal VIN′ drops to the first threshold value Vref1, Figure 6The first conduction signal S1_ON output by the first comparison circuit U01 in the circuit is reversed, and the first logic circuit 201114 controls the first signal S1 to jump from invalid to valid according to the first conduction signal S1_ON. Accordingly, the first control signal gate1 jumps from invalid to valid, controlling the first switch Q01 to turn on, and the first capacitor C01 starts to charge. At this time, the corresponding Figure 9 At time t1 and time t4; when the first capacitor voltage sampling signal VCC′ rises to the second threshold value Vref2, Figure 6 The first turn-off signal S1_OFF output by the second comparison circuit U02 in the circuit is flipped, and the first logic circuit 201114 controls the first signal S1 to jump from valid to invalid according to the first turn-off signal S1_OFF. Accordingly, the first control signal gate1 jumps from valid to invalid, controlling the first switch Q01 to turn off, and the charging of the first capacitor C01 is cut off. At this time, the corresponding Figure 9 Time t3 and time t5 in . Figure 9 , wherein, time t1 and time t4 are the times when the first capacitor C01 starts to charge, time t2 is the time when the first rectified voltage VIN is at the bottom, and time t3 and time t5 are the times when the first capacitor C01 stops charging. In one embodiment, in the corresponding Figure 9 At t3, Figure 6 The first threshold generating circuit 201112 outputs the first voltage V1. After comparing and finding that the first threshold Vref1 is greater than the first voltage V1, the first threshold generating circuit 201112 controls the first threshold Vref1 to decrease. Figure 9 In the next charging cycle shown in , the first threshold corresponding to the moment when the first capacitor starts charging (time t4) will be smaller than the first threshold corresponding to time t1. Accordingly, in this charging cycle, the first voltage output by the first threshold generating circuit 201112 at the moment when the first capacitor charging is cut off (time t5) is equal to or closer to the first threshold, and the charging efficiency is improved.

[0076] In this embodiment, the first control circuit 2011 controls the first switch to conduct when the first rectified voltage sampling signal drops to a first threshold, thereby controlling the first capacitor to begin charging. When the first capacitor voltage sampling signal rises to a second threshold, the first switch is turned off, thereby stopping the charging of the first capacitor. This allows the first rectified voltage to charge the first capacitor during the period when the first rectified voltage is near its valley. By dynamically adjusting the first threshold, charging efficiency is optimized, further improving the conversion efficiency of the linear conversion circuit 201.

[0077] Figure 7A schematic diagram of the circuit structure of a second embodiment of a linear conversion circuit is shown. In this embodiment, the circuit structure of the first control circuit 2011 is substantially the same as that of the first control circuit in the first embodiment and will not be further described here. The difference is that the first switch control circuit 20111 of this embodiment further includes a third comparison circuit U03 and a first OR logic circuit U04. The third comparison circuit U03 receives a third threshold value Vref3 at its first input terminal and a first capacitor voltage sampling signal VCC′ at its second input terminal, and generates a second signal S2 based on the comparison result between the first capacitor voltage sampling signal VCC′ and the third threshold value Vref3. The first OR logic circuit U04 receives a first signal S1 at its first input terminal and a second signal S2 at its second input terminal, and performs an OR logic operation on the first signal S1 and the second signal S2. The first switch control circuit 20111 outputs the output signal of the first OR logic circuit U04 as the first switch signal. Similarly, the first control circuit 2011 outputs the first switch signal as the first control signal gate1.

[0078] In this embodiment, when the first capacitor voltage sampling signal VCC′ is less than the third threshold value Vref3, the second signal S2 output by the third comparison circuit U03 is in an active state. Accordingly, the first control signal gate1 is also in an active state, the first switch Q01 is turned on, and the first capacitor C01 begins charging. Therefore, unlike the first embodiment, in this embodiment, the first control circuit 2011 controls the first switch to turn on when the first rectified voltage sampling signal drops to the first threshold value or when the first capacitor voltage sampling signal is less than the third threshold value, thereby controlling the first capacitor to begin charging. Compared to the first embodiment, during the startup phase, the first capacitor voltage in this embodiment is lower, enabling the first capacitor to begin charging immediately upon power-up, achieving a rapid startup of the first capacitor voltage VCC, thereby enabling the power supply circuit to output the effective supply voltage Vo earlier. In this embodiment, after the power supply circuit is started, the first capacitor voltage VCC is higher than the third threshold value, and the first control circuit 2011 will switch to controlling the first capacitor to start charging when the first rectified voltage sampling signal drops to the first threshold value, and controlling the first capacitor to stop charging when the first capacitor voltage sampling signal rises to the second threshold value; the first rectified voltage is used to charge the first capacitor during the time period when the first rectified voltage is near the valley position, and the charging efficiency is optimized by dynamically adjusting the first threshold value, thereby further improving the conversion efficiency of the linear conversion circuit.

[0079] Figure 8This is a schematic diagram of the circuit structure of a third embodiment of the linear conversion circuit according to the present invention. In this embodiment, the first control circuit 2011 includes a first switch control circuit 20111 and a current limiting circuit 20112. The circuit structure of the first switch control circuit 20111 is identical to that of the first switch control circuit in the second embodiment and is not further described here. In this embodiment, the current limiting circuit 20112 is used to limit the current when the first switch transistor Q01 is turned on. The current limiting circuit 20112 samples the current of the first switch transistor Q01 to generate a first sampling signal Vcs, and outputs a first control signal gate1 based on the first sampling signal Vcs and the first switching signal gate′ output by the first switch control circuit 20111. For example, in one embodiment, the current limiting circuit 20112 includes a sampling resistor Rcs, a current sampling circuit 201121, a selection switch K01, and a first operational amplifier U05, wherein the sampling resistor Rcs and the first switching tube Q01 are connected in series; the current sampling circuit 201121 is connected across the sampling resistor Rcs to output a first sampling signal Vcs representing the current of the first switching tube Q01; a first input terminal of the first operational amplifier U05 is connected to the output terminal of the selection switch K01, and the first input terminal receives the first sampling signal Vcs; the first input terminal of the selection switch K01 receives a reference voltage VrefA, a second input terminal is grounded, and a control terminal is connected to the output terminal of the first switch control circuit 20111 to receive the first switching signal gate′.

[0080] In this embodiment, when the first switch signal gate′ is active, the selector switch K01 connects the reference voltage VrefA to the first input terminal of the first op amp U05. At this time, the first control signal gate1 output by the first op amp U05 is active, the first switch Q01 is turned on, and the first capacitor C01 is charged. The first op amp U05 adjusts the magnitude of the first control signal gate1 based on the reference voltage VrefA and the first sampling signal Vcs to limit the current flowing through the first switch Q01, thereby limiting the current charging the first capacitor C01. When the first switch signal gate′ is inactive, the selector switch K01 connects ground to the first input terminal of the first op amp U05. At this time, the first control signal gate1 output by the first op amp U05 is inactive, and the first switch Q01 is turned off. Compared to the second embodiment, in this embodiment, the current limiting circuit 20112 is used to limit the current charging the first capacitor, thereby improving input current harmonics.

[0081] It should be noted that, in order to facilitate public understanding, this article uses Figure 6-Figure 8The three embodiments of the linear conversion circuit shown are used as examples to describe the circuit structure and operating principle of the linear conversion circuit. In the above three embodiments, the linear conversion circuit controls the first capacitor to stop charging when the first capacitor voltage sampling signal rises to the second threshold, and adjusts the first threshold based on the first rectified voltage at the time when the first capacitor charging is stopped to further improve conversion efficiency. It is understood that in another embodiment, the linear conversion circuit can control the first capacitor to stop charging when the first capacitor voltage sampling signal rises to the second threshold, and adjust the first threshold based on the first capacitor voltage sampling signal when the first capacitor starts charging; or control the first capacitor to stop charging when the first rectified voltage sampling signal rises to a fourth threshold, and adjust the first threshold based on the first capacitor voltage sampling signal when the first capacitor starts charging; or control the first capacitor to stop charging when the first rectified voltage sampling signal rises to a fourth threshold, and adjust the first threshold based on the first capacitor voltage sampling signal when the first capacitor charging is stopped. By way of further example, if the first threshold is adjusted based on the first capacitor voltage sampling signal when the first capacitor starts charging, the first threshold can be controlled to decrease when the first capacitor voltage sampling signal when the first capacitor starts charging is greater than a predetermined value; and the first threshold can be controlled to increase when the first capacitor voltage sampling signal when the first capacitor starts charging is less than the predetermined value. If the first threshold is adjusted based on the first capacitor voltage sampling signal when the first capacitor stops charging, the first threshold can be controlled to decrease when the first capacitor voltage sampling signal when the first capacitor stops charging is greater than a predetermined value; and the first threshold can be controlled to increase when the first capacitor voltage sampling signal when the first capacitor stops charging is less than the predetermined value. Those skilled in the art can easily obtain the specific circuit structure of the above scheme based on the content of this article, and will not be described in detail here.

[0082] The above-described embodiments do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the above-described embodiments shall be included in the scope of protection of this technical solution.

Claims

1. A power supply circuit for providing a power supply voltage to a load, characterized in that: It includes a linear conversion circuit, a first capacitor and a DC-DC conversion circuit, and the AC input is rectified to obtain a first rectified voltage, wherein: The linear conversion circuit receives the first rectified voltage, and the output end is connected to the first capacitor. After the power supply circuit is started, the linear conversion circuit controls the first rectified voltage to charge the first capacitor in a time period when the first rectified voltage is near a valley bottom position; The DC-DC conversion circuit receives the first capacitor voltage and performs power conversion to output the supply voltage; Among them, the voltage of the first capacitor is 30-70V, the DC-DC conversion circuit includes a switching circuit and a second control circuit, wherein the switching circuit includes a second switching tube located on the high side and a third switching tube located on the low side, the second control circuit generates a second switching signal according to the output feedback signal of the DC-DC conversion circuit to control the conduction and shutdown of the second switching tube, and the second control circuit and the second switching tube are integrated in the same chip or in the same package body using a single base island packaging frame.

2. The power supply circuit according to claim 1, characterized in that: The linear conversion circuit When the first rectified voltage sampling signal drops to a first threshold, the first capacitor is controlled to start charging; or, When the first rectified voltage sampling signal drops to the first threshold or the first capacitor voltage sampling signal is less than the third threshold, the first capacitor is controlled to start charging.

3. The power supply circuit according to claim 2, characterized in that: The linear conversion circuit controls the first capacitor to stop charging when the first capacitor voltage sampling signal rises to a second threshold value; adjusting the first threshold value according to the first rectified voltage sampling signal when the charging of the first capacitor is cut off, controlling the first threshold value to decrease when the first threshold value is greater than the first voltage, and controlling the first threshold value to increase when the first threshold value is less than the first voltage, wherein the first voltage is the first rectified voltage sampling signal when the charging of the first capacitor is cut off; or, The first threshold is adjusted according to a first capacitor voltage sampling signal when the first capacitor starts to charge. When the first capacitor voltage sampling signal when the first capacitor starts to charge is greater than a first predetermined value, the first threshold is controlled to decrease. When the first capacitor voltage sampling signal when the first capacitor starts to charge is less than the first predetermined value, the first threshold is controlled to increase.

4. The power supply circuit according to claim 2, characterized in that: The linear conversion circuit controls the first capacitor to stop charging when the first rectified voltage sampling signal rises to a fourth threshold value; The first threshold is adjusted according to a first capacitor voltage sampling signal when the first capacitor starts to charge, and the first threshold is controlled to decrease when the first capacitor voltage sampling signal when the first capacitor starts to charge is greater than a first predetermined value, and the first threshold is controlled to increase when the first capacitor voltage sampling signal when the first capacitor starts to charge is less than the first predetermined value; or The first threshold is adjusted according to the first capacitor voltage sampling signal when the first capacitor charging is cut off. When the first capacitor voltage sampling signal when the first capacitor charging is cut off is greater than a second predetermined value, the first threshold is controlled to decrease. When the first capacitor voltage sampling signal when the first capacitor charging is cut off is less than the second predetermined value, the first threshold is controlled to increase.

5. The power supply circuit according to claim 1, characterized in that: At least part of the linear conversion circuit is integrated into the same chip or the same package.

6. The power supply circuit according to claim 2, characterized in that: The linear conversion circuit includes a first switch tube and a first control circuit, wherein: The first power end of the first switch tube receives the first rectified voltage, and the second power end is connected to the first capacitor; The first control circuit includes a first switch control circuit, which receives the first rectified voltage and the first capacitor voltage to generate a first switch signal. The first control circuit generates a first control signal according to the first switch signal. The control end of the first switch tube receives the first control signal, wherein the first control signal controls the conduction and shutdown of the first switch tube according to the first switch signal.

7. The power supply circuit according to claim 6, characterized in that: The first switch control circuit comprises: An input voltage sampling circuit samples the first rectified voltage to output the first rectified voltage sampling signal and a first voltage, wherein the first voltage is the first rectified voltage sampling signal when the first switch tube starts to turn off; a first threshold generating circuit, configured to output the first threshold, wherein the first threshold generating circuit adjusts the first threshold according to the first voltage, and when the first threshold is greater than the first voltage, the first threshold generating circuit controls the first threshold to decrease, and when the first threshold is less than the first voltage, the first threshold generating circuit controls the first threshold to increase; A first comparison circuit, wherein a first input terminal receives the first threshold value, a second input terminal receives the first rectified voltage sampling signal, and generates a first conduction signal according to a comparison result of the first rectified voltage sampling signal and the first threshold value; A first capacitor voltage sampling circuit, sampling the first capacitor voltage to output the first capacitor voltage sampling signal; a second comparison circuit, wherein a first input terminal receives the first capacitor voltage sampling signal, a second input terminal receives a second threshold, and generates a first shutdown signal according to a comparison result of the first capacitor voltage sampling signal and the second threshold; A first logic circuit receives the first on signal and the first off signal to output a first signal; The first switch control circuit outputs the first signal as the first switch signal.

8. The power supply circuit according to claim 7, characterized in that: The first switch control circuit further includes: a third comparison circuit, wherein a first input terminal receives the third threshold value, a second input terminal receives the first capacitor voltage sampling signal, and generates a second signal according to a comparison result of the first capacitor voltage sampling signal and the third threshold value; A first OR logic circuit, wherein a first input terminal receives the first signal, a second input terminal receives the second signal, and performs an OR logic operation on the first signal and the second signal; The first switch control circuit outputs the output signal of the first OR logic circuit as the first switch signal.

9. The power supply circuit according to claim 6, characterized in that: The first control circuit outputs the first switch signal as the first control signal.

10. The power supply circuit according to claim 6, characterized in that: The first control circuit also includes a current limiting circuit for limiting the current when the first switch tube is turned on. The current limiting circuit samples the current of the first switch tube to obtain a first sampling signal, and outputs the first control signal according to the first sampling signal and the first switch signal.

11. The power supply circuit according to claim 6, characterized in that: The first switch tube is integrated in the same chip or the same package.

12. The power supply circuit according to claim 1, characterized in that: The DC-DC conversion circuit is a Buck circuit.

13. An LED driving system, characterized in that: It comprises a rectifier circuit, a wireless module, an LED drive circuit and a power supply circuit as claimed in any one of claims 1 to 12, wherein: The rectifier circuit is connected to an AC input power supply, and outputs the first rectified voltage after rectifying the AC input; The power supply circuit receives the first rectified voltage to output the power supply voltage, and the power supply voltage is used to power the wireless module; The wireless module is used to output a dimming signal; The LED driving circuit is used to provide a driving current to an LED load, and the LED driving circuit receives the dimming signal to adjust the magnitude of the driving current.

14. The LED driving system according to claim 13, characterized in that: At least part of the circuit in the linear conversion circuit and at least part of the LED driving circuit are integrated in the same chip or the same package.

15. The LED driving system according to claim 13, characterized in that: The linear conversion circuit includes a first switch tube, a first power terminal of the first switch tube receives the first rectified voltage, and a second power terminal is connected to the first capacitor; The first switch tube and at least a part of the LED driving circuit are integrated in the same chip or the same package.

16. The LED driving system according to claim 13, characterized in that: The rectifier circuit comprises a rectifier bridge, The rectifier bridge receives the AC input to output the first rectified voltage, and the input end of the LED driving circuit receives the first rectified voltage.

17. The LED driving system according to claim 13, characterized in that: The rectifier circuit includes a rectifier bridge and a unidirectional conductive device. The rectifier bridge receives the AC input to output a second rectified voltage, and the input end of the LED driving circuit receives the second rectified voltage; The anode of the unidirectional conductive device is connected to one end of the AC input power source, the cathode of the unidirectional conductive device is connected to the first input end of the power supply circuit, and the second input end of the power supply circuit is grounded.

18. The LED driving system according to claim 13, characterized in that: The wireless module includes at least one of a wifi module, a bluetooth module and a ZigBee module.

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