LED drive circuit and electronic equipment

Abstract

The utility model relates to an LED drive circuit and an electronic device. The LED driving circuit comprises a power supply input end, a power supply output end, a boost constant current unit, a turn-back temperature setting unit and a ripple offset unit, the power input end is used for connecting commercial power input to provide power input to supply power to the driving circuit; the power output end is used for being connected with the LED module and providing power output to drive the LED module to work; the boost constant-current unit is connected with the power input end and the power output end and is used for performing voltage conversion on power supply input to obtain power output; the turn-back temperature setting unit is connected with the boost constant current unit, and the boost constant current unit is configured to set the turn-back temperature according to the turn-back temperature setting unit; and the ripple offset unit is connected with the power supply output end and is used for performing power frequency ripple offset elimination on the power supply output. According to the utility model, LED constant current power supply can be realized, LED stroboflash can be eliminated, and user experience can be improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to LED power supply technical field more specifically, relate to a kind of LED drive circuit and electronic equipment. BACKGROUND

[0002] In traditional Boost LED drive circuit, input power frequency ripple (100Hz / 120Hz) can be transmitted to the both ends of LED light-emitting circuit, resulting in the current fluctuation of LED in LED light-emitting circuit, causing the video flicker of human eye, and causing the user to have bad use experience. For the video flicker that can be caused, the current common solution is to increase the output capacitor in the drive circuit or to increase the switching frequency, the cost of the whole circuit design is high, at the same time, it will make the size of the circuit become larger, and in some cases, it will bring the problem of increasing EMI. Moreover, the elimination effect of power frequency ripple cannot be optimal. In some other solutions, a linear constant current circuit can be added in the rear stage of the drive circuit, which will also make the whole circuit become complex and the cost is higher. UTILITY MODEL CONTENT

[0003] The technical problem to be solved by the utility model is to provide a kind of LED drive circuit and electronic equipment for the above-mentioned part of the technical defects of prior art.

[0004] The technical scheme adopted by the utility model to solve its technical problem is: a kind of LED drive circuit is constructed and includes: power input end, power output end, boost constant current unit, foldback temperature setting unit and ripple cancellation unit;

[0005] The power input end is used to connect the mains input to provide power input to the drive circuit for power supply;

[0006] The power output end is used to connect LED module to provide power output to the LED module;

[0007] The boost constant current unit is connected with the power input end and the power output end, and is used to convert the voltage of the power supply input to obtain the power output;

[0008] The foldback temperature setting unit is connected with the boost constant current unit, wherein the boost constant current unit is configured to set the foldback temperature according to the foldback temperature setting unit;

[0009] The ripple cancellation unit is connected with the power output end and the LED module, and is used to cancel the power frequency ripple of the power output.

[0010] Preferably, in the embodiment of the LED drive circuit of the utility model, the ripple cancellation unit includes a first capacitor, a voltage stabilizing tube and a PMOS tube;

[0011] The first end of the first capacitor is connected to the power output end, wherein the power output end is used for connecting the positive electrode of the LED module.

[0012] The second end of the first capacitor is connected to the cathode of the voltage stabilizing tube and the gate of the PMOS tube, and the source of the PMOS tube is used for connecting the negative electrode of the LED module.

[0013] The anode of the voltage stabilizing tube and the drain of the PMOS tube are grounded respectively.

[0014] Preferably, in the embodiment of the LED driving circuit, the boost constant current unit comprises a boost constant current chip, an input sampling circuit, an output sampling circuit, a driving switch circuit and a boost circuit.

[0015] The input sampling circuit is connected to the power input end and is used for sampling the power input to obtain an input sampling voltage.

[0016] The under-voltage protection pin of the boost constant current chip is connected to the input sampling circuit and is used for receiving the input sampling voltage to output a driving level through the driving signal output pin of the boost constant current chip and triggering under-voltage protection when the power input is under-voltage.

[0017] The output sampling circuit is connected to the power output end and is used for sampling the power output to obtain an output sampling voltage.

[0018] The over-voltage protection pin of the boost constant current chip is connected to the output sampling circuit and is used for receiving the output sampling circuit to trigger over-voltage protection when the power output is over-voltage.

[0019] The driving switch circuit is connected to the driving signal output pin of the boost constant current chip and is configured to be turned on or turned off according to the driving level.

[0020] The boost circuit is connected to the power input end, the power output end and the driving switch circuit and is used for providing the power output according to the on or off time of the driving switch circuit.

[0021] Preferably, in the embodiment of the LED driving circuit, the boost constant current chip is internally provided with a first switch and a second switch.

[0022] The first switch is connected to the under-voltage protection pin of the boost constant current chip and the power supply input pin of the boost constant current chip and is configured to be in an on state within a preset time length of power-on of the boost constant current chip.

[0023] The second switch connects an overvoltage protection pin of the boost constant current chip and a ground pin of the boost constant current chip, and is configured to be in an on state within a preset time length of power-on of the boost constant current chip.

[0024] The boost constant current chip is configured to obtain a voltage of an undervoltage protection pin of the boost constant current chip when the first switch and the second switch are on, so as to set the turn-back temperature according to the voltage.

[0025] Preferably, in the embodiment of the LED driving circuit, the turn-back temperature setting unit comprises a first resistor and a first diode.

[0026] The first end of the first resistor is connected to the undervoltage protection pin of the boost constant current chip, the second end of the first resistor is connected to the anode of the first diode, and the cathode of the first diode is connected to the overvoltage protection pin of the boost constant current chip.

[0027] Preferably, in the embodiment of the LED driving circuit, the input sampling circuit comprises a second resistor and a third resistor.

[0028] The first end of the second resistor is connected to the power input end, the second end of the second resistor is connected to the first end of the third resistor and the undervoltage protection pin of the boost constant current chip, and the second end of the third resistor is grounded.

[0029] Preferably, in the embodiment of the LED driving circuit, the output sampling circuit comprises a fourth resistor and a fifth resistor.

[0030] The first end of the fourth resistor is connected to the power output end, the second end of the fourth resistor is connected to the first end of the fifth resistor and the overvoltage protection pin of the boost constant current chip, and the second end of the fifth resistor is grounded.

[0031] Preferably, in the embodiment of the LED driving circuit, the boost circuit comprises a transformer, a second diode, a third diode, a fourth diode and a sixth resistor.

[0032] The first end of the transformer is connected to the anode of the second diode, the cathode of the second diode is connected to the first end of the sixth resistor, and the second end of the sixth resistor is connected to the power supply input pin of the boost constant current chip.

[0033] The second end of the transformer is grounded, the third end of the transformer is connected to the anode of the third diode and the driving switch circuit, and the cathode of the third diode is connected to the power output end.

[0034] The fourth end of the transformer is connected with the power input end and the anode of the fourth diode.

[0035] Preferably, in the embodiment of the LED driving circuit of the utility model, the driving switch circuit comprises a first MOS tube and a seventh resistor.

[0036] The gate of the first MOS tube is connected with the driving signal output pin of the boost constant current chip, the source of the first MOS tube is connected with the current detection pin of the boost constant current chip and the first end of the seventh resistor, and the drain of the first MOS tube is connected with the anode of the third diode.

[0037] The utility model discloses still a kind of electronic equipment, including LED module, and the LED driving circuit as described above, wherein, the LED driving circuit is powered to the LED module by power output end.

[0038] The utility model discloses a kind of LED driving circuit and electronic equipment, with following beneficial effects: it can realize LED constant current power supply while eliminating LED stroboscopic, improve user experience. BRIEF DESCRIPTION OF DRAWINGS

[0039] The utility model will be further described below in conjunction with drawings and embodiment, and in the drawings:

[0040] Figure 1 It is the structure schematic diagram of an embodiment of the utility model one kind of LED driving circuit;

[0041] Figure 2 It is the circuit schematic diagram of an embodiment of the utility model one kind of LED driving circuit;

[0042] Figure 3 It is the logic block diagram of the first embodiment of the partial circuit diagram of the utility model one kind of LED driving circuit in boost constant current chip;

[0043] Figure 4 It is the partial circuit diagram of the utility model one kind of LED driving circuit in boost constant current chip;

[0044] Figure 5 It is the partial circuit diagram of existing boost constant current chip. DETAILED DESCRIPTION

[0045] In order to have more clear understanding to the technical features, object and effect of the utility model, now detailed description of the specific implementation mode of the utility model is made by comparing with drawings.

[0046] As Figure 1 Shown, it shows an embodiment of the utility model one kind of LED driving circuit.In Figure 1In an embodiment of the LED driving circuit shown in the utility model, the LED driving circuit comprises: a power input end 110, a power output end 130, a boost constant current unit 120, a foldback temperature setting unit 140 and a ripple cancellation unit 150; the power input end 110 is used for connecting the mains input to provide power input for the driving circuit; the power output end 130 is used for connecting the LED module 200 to provide power output to the LED module 200; the boost constant current unit 120 is connected to the power input end 110 and the power output end 130 and is used for converting the voltage of the power input to obtain the power output; the foldback temperature setting unit 140 is connected to the boost constant current unit 120, wherein the boost constant current unit 120 is configured to set the foldback temperature according to the foldback temperature setting unit 140; the ripple cancellation unit 150 is connected to the power output end 130 and the LED module 200 and is used for canceling the power frequency ripple of the power output.

[0047] Specifically, in the LED driving circuit, the mains input is connected through the power input end 110 to provide the power input through the mains input, which is used to provide power for the LED driving circuit. The internal circuit of the LED driving circuit converts the power input to provide the power output through the power output end 130 to supply power to the LED module 200 through the power output, so that the LED module 200 works normally, and finally the LED driving circuit drives the LED module 200. Here, the LED module 200 can be understood as an LED light-emitting module, which contains one or more LED lights. The boost constant current unit 120 is connected to the power input end 110 and the power output end 130 to convert the voltage of the power input to obtain the power output. The boost constant current unit 120 can be understood as providing constant current output for the LED module 200. The foldback temperature setting unit 140 is used to set the foldback temperature of the boost constant current unit 120, that is, when the boost constant current unit 120 works, it will be internally configured according to the setting of the foldback temperature setting unit 140 to obtain the foldback temperature when the boost constant current unit 120 works. When the circuit operating temperature or the ambient temperature reaches the foldback temperature, the boost constant current unit 120 will automatically adjust the output current, which can also be understood as adjusting the power output to suppress the continuous rise of the circuit temperature, realizing the temperature protection function. The process of adjusting the power output or the output current of the boost constant current unit 120 according to the foldback temperature can be obtained according to the existing working process of the boost constant current unit 120, which is not described here and is not limited as protection. In the working process of the driving circuit, the power output of the boost constant current unit 120 is subjected to power frequency ripple cancellation through the ripple cancellation unit 150 to avoid video flicker when the LED module 200 works, improving the user experience.

[0048] As Figure 2As shown, in one embodiment, the ripple cancellation unit 150 includes a first capacitor, a Zener diode, and a PMOS transistor; the first terminal of the first capacitor is connected to a power output terminal 130, wherein the power output terminal 130 is used to connect to the positive terminal of the LED module 200; the second terminal of the first capacitor is connected to the cathode of the Zener diode and the gate of the PMOS transistor, and the source of the PMOS transistor is used to connect to the negative terminal of the LED module 200; the anode of the Zener diode and the drain of the PMOS transistor are respectively grounded. Specifically, in the ripple cancellation unit 150... The first capacitor may include capacitor C1, the Zener diode may include Zener diode Z1, and the PMOS transistor may include MOSFET Q1. Capacitor C1 is used to couple the power frequency ripple of the power supply output (powering the positive terminal of LED module 200) to the gate of MOSFET Q1. The drain of MOSFET Q1 is grounded, and the source of MOSFET Q1 is connected to the negative terminal of LED module 200. MOSFET Q1 forms a common drain-source follower, which is used to transmit the power frequency ripple of the gate of MOSFET Q1 to the follower terminal (corresponding to the negative terminal of LED module 200), so that the positive and negative terminals of LED module 200 have ripples that are mutually opposite, and the voltages reaching the positive and negative terminals of LED module 200 are constant.

[0049] A more specific understanding is that the power frequency ripple ΔV in the power output (corresponding to the positive input of LED module 200) LED+ The voltage is transferred to the gate of MOSFET Q1 through capacitor C1, causing the gate voltage fluctuation of MOSFET Q1 to be ΔGate≈ΔV. LED+ Simultaneously, MOSFET Q1 transmits gate fluctuations to the source, causing the power frequency ripple ΔV corresponding to the negative terminal of LED module 200 to... LED- ≈ΔGate≈ΔV LED+ The voltage difference ΔV between the positive and negative electrodes of LED module 200 LED =V LED+ -V LED- ≈(V LED+_avg +ΔV LED+ )-(V LED-_avg +Δ VLED- ) = V LED+_avg -V LED-_avg =A constant value, thereby eliminating current ripple and visible flicker. Where V LED+_avg This refers to the average positive voltage (DC value) of the LED module, V. LED-_avg This refers to the average value (DC value) of the negative electrode voltage of the LED module.

[0050] In the ripple cancellation unit 150, the voltage stabilizing tube Z1 is used to protect the MOS tube Q1. For example, the gate voltage (Vgate) of the MOS tube Q1 is limited to be less than a preset value, and then the drain voltage of the MOS tube Q1 is also limited to be Vgate+Vth, so as to prevent the drain voltage of the MOS tube Q1 from exceeding the VDS voltage resistance of the MOS. Vth refers to the conduction threshold of the MOS tube Q1, which is generally 2-4V. The preset value can be set according to the specification of the MOS tube Q1, and in a specific embodiment, the preset value can be set to 10V.

[0051] Optionally, the boost constant current unit 120 includes a boost constant current chip U1, an input sampling circuit 121, an output sampling circuit 124, a driving switch circuit 123, and a boost circuit 122; the input sampling circuit 121 is connected to the power input end 110, and is used to sample the power input to obtain an input sampling voltage; an under-voltage protection pin of the boost constant current chip is connected to the input sampling circuit 121, and is used to receive the input sampling voltage to output a driving level through a driving signal output pin of the boost constant current chip U1, and trigger under-voltage protection when the power input is under-voltage; the output sampling circuit 124 is connected to the power output end 130, and is used to sample the power output to obtain an output sampling voltage; an over-voltage protection pin of the boost constant current chip U1 is connected to the output sampling circuit 124, and is used to receive the output sampling circuit 124 to trigger over-voltage protection when the power output is over-voltage; the driving switch circuit 123 is connected to the driving signal output pin of the boost constant current chip U1, so as to be turned on or turned off according to the driving level; the boost circuit 122 is connected to the power input end 110, the power output end 130, and the driving switch circuit 123, and is used to provide the power output according to the on or off time of the driving switch circuit 123.

[0052] Specifically, in the boost constant current unit 120, the boost constant current chip U1 samples the power input (corresponding to the input sampling circuit 121) and the power output (corresponding to the output sampling circuit 124) through the input sampling circuit 121 and the output sampling circuit 124, respectively, and then outputs a driving level through the driving signal output pin according to the input sampling voltage and the output sampling voltage. Figure 2The input detection is performed to the input detection result to perform the corresponding operation. Based on the working characteristics of the general boost constant current chip, taking the chip LZC6200 as an example, the boost constant current chip U1 can output the driving signal to control the driving switch circuit 123 to act, so as to realize the synchronization of the envelope of the output current of the power supply output and the sampled sine wave signal, so as to obtain good PF and THD, and provide the control effect of the LED module 200. At the same time, the boost constant current chip U1 can also realize the input under-voltage protection through the input detection result. The above processes can be realized according to the current chip function, for example, the input sampling and input over-voltage protection circuit inside the chip is realized. The specific processing process is not limited and protected here, and the emphasis here is to emphasize the connection relationship based on the boost constant current chip U1. For example, the input sampling and input over-voltage protection circuit inside the chip can refer to the circuit structure of the existing chip. In addition, the boost constant current chip U1 can also perform output detection on the power supply output through the output sampling circuit 124, so as to perform the corresponding operation according to the output detection result. For example, according to the general working characteristics of the boost constant current corresponding chip, the over-voltage protection is realized according to the output detection result by the internal functional unit of the chip, for example, the output over-voltage protection circuit inside the chip. The process can also be realized according to the current chip function, and the specific processing process is not limited and protected here, and the emphasis here is to emphasize the connection relationship based on the boost constant current chip U1. For example, the output over-voltage protection circuit inside the chip can refer to the circuit structure of the existing chip.

[0053] At the same time, based on the foldback temperature setting function of the boost constant current chip U1, the foldback temperature setting is performed through the identification process of the foldback temperature setting unit 140. In some embodiments, the connection relationship between the foldback temperature setting unit 140 and the boost constant current chip U1 can be set according to the setting of the boost constant current chip to realize the foldback temperature setting process.

[0054] In an embodiment, the boost constant current chip U1 is provided with a first switch and a second switch; the first switch is connected to the under-voltage protection pin of the boost constant current chip U1 and the power supply input pin of the boost constant current chip U1, and is configured to be in an on state within a preset time length of the power-on of the boost constant current chip U1; the second switch is connected to the over-voltage protection pin of the boost constant current chip U1 and the ground pin of the boost constant current chip U1, and is configured to be in an on state within a preset time length of the power-on of the boost constant current chip U1; the boost constant current chip U1 is configured to obtain the voltage of the under-voltage protection pin of the boost constant current chip U1 when the first switch and the second switch are turned on to set the foldback temperature according to the voltage.

[0055] Specifically, as shown in FIG. 1, the boost constant current chip U1 is connected to the input sampling circuit 120 and the output sampling circuit 124, and is connected to the foldback temperature setting unit 140. Figure 3As shown, based on the structure of the existing boost constant current chip U1, for example, based on the internal structure of chip LZC6200, switches S1 (corresponding to the first switch) and S2 (corresponding to the second switch) are added inside the boost constant current chip U1, wherein the switch S1 is used to control the conduction or turn-off of the UVS pin (corresponding to the under-voltage protection pin of the boost constant current chip U1) of the boost constant current chip U1 and the VCC pin (corresponding to the power supply input pin of the boost constant current chip U1) of the boost constant current chip U1, the switch S2 is used to control the conduction or turn-off of the FB pin (corresponding to the over-voltage protection pin of the boost constant current chip U1) of the boost constant current chip U1 and the ground, and at the same time, the voltage of the UVS pin of the boost constant current chip U1 is obtained by the temperature setting circuit inside the boost constant current chip U1 when the switches S1 and S2 are turned on, so as to set the foldback temperature according to the voltage result. Here, it is emphasized that the temperature setting circuit inside the boost constant current chip U1 is an existing circuit, that is, the process of setting the foldback temperature according to the voltage result of the boost constant current chip U1 can adopt the existing technical process, and the software processing process is not protected here. In this application, it is emphasized that by adding switches S1 and S2 to the existing chip, the connection relationship is constructed to realize the pin borrowing of the existing chip, that is, the UVS pin and the FB pin of the boost constant current chip U1 are borrowed to realize the identification process of the foldback temperature setting unit 140. The structure of the temperature setting circuit inside the boost constant current chip can refer to the existing temperature setting circuit in the boost constant current chip as shown in Figure 5 The comparison circuit can include at least one or more comparators, and the boost constant current chip can output a comparison result through the comparison circuit according to the obtained voltage. The boost constant current chip inside the software sets the foldback temperature according to the comparison result.

[0056] Optionally, the return temperature setting unit 140 comprises a first resistor and a first diode; a first end of the first resistor is connected to the under-voltage protection pin of the boost constant current chip U1, a second end of the first resistor is connected to the anode of the first diode, and the cathode of the first diode is connected to the over-voltage protection pin of the boost constant current chip U1. Specifically, in the return temperature setting unit 140, the first resistor comprises a resistor R1, and the first diode comprises a diode D1. In the specific return temperature setting process, when the switch S1 and the switch S2 are turned on, the FB pin of the boost constant current chip U1 is pulled low, and the voltage of the UVS pin of the boost constant current chip U1 is pulled low through the diode D1 connected between the UVS pin of the boost constant current chip U1 and the FB pin of the boost constant current chip U1, at the same time, the UVS pin of the boost constant current chip U1 is provided with a preset value such as 30uA of current from the VCC pin of the boost constant current chip U1 to load on the resistor R1, and the temperature setting circuit inside the boost constant current chip U1 processes to obtain the set temperature return gear according to the voltage value of the UVS pin of the boost constant current chip U1 through detecting the voltage value.

[0057] In a specific embodiment, as shown in Figure 4 the temperature setting circuit in the boost constant current chip U1 can perform the specific temperature setting process according to the comparison result of the comparison circuit therein during the specific working process. For example, when the switch S1 and the switch S2 are turned on, if the diode VF=0.7V, V 判定 =0.7V+30uA*R1. R1 is the resistance value of the resistor R1, which is different, and V 判定 voltage is different, and then different return temperatures can be corresponded according to different voltages. In the specific implementation process, V 判定 is compared with the reference voltage such as 1.5V and 3V through the comparison circuit, and different temperature conversion points are obtained. The specific process is as follows: when R1=0kΩ, V 判定 =0.7V+30uA*R1=0.7V, at this time V 判定 =0.7V<1.5V, and then the temperature conversion point is set to a preset value according to the judgment result, for example, 121℃. When R1=56kΩ, V 判定 =0.7V+30uA*R1=2.38V at this time 1.5V<V 判定 =2.38V<3V, and then the temperature conversion point can be set to another preset value according to the judgment result, for example, 132℃. When R1=100kΩ, 判定= 0.7V + 30uA * R1 = 3.7V At this time, Vjudge = 2.38V > 3V, so the temperature turning point can be set to other preset value according to the determination result, for example, 150℃. That is, through the process, the setting of the turn-back temperature according to the determination result of the setting unit 140 can be realized. It should be emphasized that the process of setting the turn-back temperature according to the detection voltage in the boost constant current chip in the embodiment can refer to the existing turn-back temperature setting process of the boost constant current chip, and the software processing process thereof is not limited here.

[0058] Among them, the on-off control of the switch S1 and the switch S2 can be set to be performed within the preset time length of the power-on of the boost constant current chip U1, so as to obtain the turn-back temperature corresponding to the current LED driving circuit when the boost constant current chip U1 starts to work.

[0059] Through the above process, compared with the traditional Boost LED driving circuit, the temperature turning point setting usually needs to occupy a separate pin. Generally, the LED driving chip is mostly small package (6pin or 8pin), and the pin resource is scarce. The more pin, the more difficult and costly the package will be. Through the process of the embodiment, the pin occupation of the boost constant current chip U1 can be reduced, so that the pin design can be reduced on the basis of the current general chip in the design process of the boost constant current chip U1, so as to realize the improvement of the chip.

[0060] In an embodiment, the input sampling circuit 121 includes a second resistor and a third resistor; the first end of the second resistor is connected to the power input end 110, the second end of the second resistor is connected to the first end of the third resistor and the under-voltage protection pin of the boost constant current chip U1, and the second end of the third resistor is grounded. Specifically, as shown in Figure 2 , in the input sampling circuit 121, the second resistor includes a resistor R2, and the third resistor includes a resistor R3. The resistor R2 and the resistor R3 constitute a voltage dividing circuit, divide the voltage of the power input, and obtain the corresponding voltage sampling result at the voltage dividing output end (the series connection node of the resistor R2 and the resistor R3) and input the voltage sampling result to the UVS pin of the boost constant current chip U1.

[0061] In an embodiment, the output sampling circuit 124 includes a fourth resistor and a fifth resistor; the first end of the fourth resistor is connected to the power output end 130, the second end of the fourth resistor is connected to the first end of the fifth resistor and the over-voltage protection pin of the boost constant current chip U1, and the second end of the fifth resistor is grounded. Specifically, as shown in Figure 2 , in the output sampling circuit 124, the fourth resistor includes a resistor R4, and the fifth resistor includes a resistor R5. The resistor R4 and the resistor R5 constitute a voltage dividing circuit, divide the voltage of the power output, and obtain the corresponding voltage sampling result at the voltage dividing output end (the series connection node of the resistor R4 and the resistor R5) and input the voltage sampling result to the FB pin of the boost constant current chip U1.

[0062] In an embodiment, the boost circuit 122 comprises a transformer, a second diode, a third diode, a fourth diode and a sixth resistor; a first end of the transformer is connected to an anode of the second diode, a cathode of the second diode is connected to a first end of the sixth resistor, a second end of the sixth resistor is connected to a power supply input pin of the boost constant current chip U1; a second end of the transformer is grounded, a third end of the transformer is connected to an anode of the third diode and the driving switch circuit 123, a cathode of the third diode is connected to the power supply output end 130; a fourth end of the transformer is connected to the power supply input end 110 and an anode of the fourth diode. Specifically, as shown in the figure, in the boost circuit 122, the transformer comprises a transformer T1, the second diode comprises a diode D2, the third diode comprises a diode D3, the sixth resistor comprises a resistor R6, and the fourth diode comprises a diode D4. Among them, the capacitor C2, the transformer T1, the diode D3, the capacitor C1 and the driving switch circuit together constitute the main power loop of the boost circuit, the auxiliary winding of the transformer T1 supplies power to the VCC of the boost constant current chip U1 through the diode D2 and the resistor R6, and the diode D4 is used for initial bypassing of the transformer T1 during power-on to prevent causing power-on LC oscillation. Figure 2

[0063] Optionally, the driving switch circuit 123 comprises a first MOS tube and a seventh resistor; a gate of the first MOS tube is connected to a driving signal output pin of the boost constant current chip U1, a source of the first MOS tube is connected to a current detection pin of the boost constant current chip U1 and a first end of the seventh resistor, a drain of the first MOS tube is connected to an anode of the third diode, and a second end of the seventh resistor is grounded. Specifically, as shown in the figure, in the driving switch circuit 123, the first MOS tube comprises a MOS tube Q2, and the seventh resistor comprises a resistor R7. The MOS tube Q2 is turned on or turned off according to the driving signal output by the DRV pin (corresponding to the driving signal output pin of the boost constant current chip U1) of the boost constant current chip U1. At the same time, the resistor R7 is used as a current sampling resistor to obtain a current sampling result input to the CS pin (corresponding to the current detection pin of the boost constant current chip U1) of the boost constant current chip U1. The boost constant current chip U1 performs an internal control process according to the current sampling result. The process can refer to the specific working principle of the corresponding boost constant current chip, which can be specifically set according to the specific application scenario, and here it is not limited and protected. Figure 2

[0064] ​​Further, the utility model provides a kind of electronic equipment, including LED module 200, and the LED driving circuit as above, wherein, LED driving circuit is powered to LED module 200 by power output terminal 130. Specifically, LED driving circuit is powered to LED module 200 by power output terminal 130, by eliminating the power frequency ripple of power supply to LED module 200, reach the purpose of eliminating the video flash of LED lamp in LED module 200, improve user experience. Wherein LED module 200 can include one or more LED lamps, multiple LED lamps can be connected by series or parallel and series-parallel combination combined way form connection relationship.

[0065] It can be understood that the above embodiments only express the preferred embodiments of the utility model, and the description is more specific and detailed, but it cannot be understood as the limitation of the scope of the utility model patent;It should be pointed out that for ordinary skilled person in the art, the above technical features can be freely combined without departing from the concept of the utility model, and some modifications and improvements can be made, which belong to the protection scope of the utility model;Therefore, any equivalent transformation and modification within the scope of the claims of the utility model should belong to the scope of the claims of the utility model.

Claims

1. An LED driving circuit, characterized by, The application relates to a power supply device for LED module, which comprises the following parts: a power input end, a power output end, a voltage-boosting constant-current unit, a foldback temperature setting unit and a ripple cancellation unit; the power input end is used for connecting a commercial power input to provide power input for the driving circuit; the power output end is used for connecting an LED module to provide power output to the LED module; the voltage-boosting constant-current unit is connected with the power input end and the power output end and is used for voltage conversion of the power input to obtain the power output; the foldback temperature setting unit is connected with the voltage-boosting constant-current unit, wherein the voltage-boosting constant-current unit is configured to set a foldback temperature according to the foldback temperature setting unit; the ripple cancellation unit is connected with the power output end and the LED module and is used for power frequency ripple cancellation of the power output.

2. The LED driving circuit according to claim 1, characterized in that, The ripple cancellation unit comprises a first capacitor, a voltage stabilizing tube and a PMOS tube. The first end of the first capacitor is connected with the power output end, wherein the power output end is used for connecting the positive pole of the LED module; the second end of the first capacitor is connected with the cathode of the voltage stabilizing tube and the gate of the PMOS tube, and the source of the PMOS tube is used for connecting the negative pole of the LED module; the anode of the voltage stabilizing tube and the drain of the PMOS tube are grounded.

3. The LED driving circuit of claim 1, wherein, The voltage-boosting constant-current unit comprises a voltage-boosting constant-current chip, an input sampling circuit, an output sampling circuit, a driving switch circuit and a voltage-boosting circuit. The input sampling circuit is connected with the power input end and is used for input sampling of the power input to obtain an input sampling voltage; the under-voltage protection pin of the voltage-boosting constant-current chip is connected with the input sampling circuit and is used for receiving the input sampling voltage to output a driving level through the driving signal output pin of the voltage-boosting constant-current chip and triggering under-voltage protection when the power input is under-voltage; the output sampling circuit is connected with the power output end and is used for output sampling of the power output to obtain an output sampling voltage; the over-voltage protection pin of the voltage-boosting constant-current chip is connected with the output sampling circuit and is used for receiving the output sampling circuit to trigger over-voltage protection when the power output is over-voltage; the driving switch circuit is connected with the driving signal output pin of the voltage-boosting constant-current chip and is used for conduction or cut-off according to the driving level; the voltage-boosting circuit is connected with the power input end, the power output end and the driving switch circuit and is used for providing the power output according to the conduction or cut-off time of the driving switch circuit.

4. The LED driving circuit of claim 3, wherein, The voltage-boosting constant-current chip is provided with a first switch and a second switch; the first switch is connected with the under-voltage protection pin of the voltage-boosting constant-current chip and the power input pin of the voltage-boosting constant-current chip and is configured to be in a conduction state within a preset time length of power-on of the voltage-boosting constant-current chip; the second switch is connected with the over-voltage protection pin of the voltage-boosting constant-current chip and the grounding pin of the voltage-boosting constant-current chip and is configured to be in a conduction state within a preset time length of power-on of the voltage-boosting constant-current chip; the voltage-boosting constant-current chip is configured to obtain the voltage of the under-voltage protection pin of the voltage-boosting constant-current chip when the first switch and the second switch are in conduction to set the foldback temperature according to the voltage.

5. The LED driving circuit of claim 4, wherein, The turn-back temperature setting unit comprises a first resistor and a first diode; The first end of the first resistor is connected to the under-voltage protection pin of the boost constant current chip, and the second end of the first resistor is connected to the anode of the first diode; the cathode of the first diode is connected to the over-voltage protection pin of the boost constant current chip.

6. The LED driving circuit of claim 3, wherein, The input sampling circuit comprises a second resistor and a third resistor; The first end of the second resistor is connected to the power input end, and the second end of the second resistor is connected to the first end of the third resistor and the under-voltage protection pin of the boost constant current chip; the second end of the third resistor is grounded.

7. The LED driving circuit of claim 3, wherein, The output sampling circuit comprises a fourth resistor and a fifth resistor; The first end of the fourth resistor is connected to the power output end, and the second end of the fourth resistor is connected to the first end of the fifth resistor and the over-voltage protection pin of the boost constant current chip; the second end of the fifth resistor is grounded.

8. The LED driving circuit of claim 3, wherein, The boost circuit comprises a transformer, a second diode, a third diode, a fourth diode and a sixth resistor; The first end of the transformer is connected to the anode of the second diode, and the cathode of the second diode is connected to the first end of the sixth resistor; the second end of the sixth resistor is connected to the power supply input pin of the boost constant current chip. The second end of the transformer is grounded, the third end of the transformer is connected to the anode of the third diode and the driving switch circuit, and the cathode of the third diode is connected to the power output end; The fourth end of the transformer is connected to the power input end and the anode of the fourth diode.

9. The LED driving circuit of claim 8, wherein, The driving switch circuit comprises a first MOS transistor and a seventh resistor; The gate of the first MOS transistor is connected to the driving signal output pin of the boost constant current chip, the source of the first MOS transistor is connected to the current detection pin of the boost constant current chip and the first end of the seventh resistor, the drain of the first MOS transistor is connected to the anode of the third diode, and the second end of the seventh resistor is grounded.

10. An electronic device, comprising: The LED driving circuit comprises an LED module, and the LED driving circuit supplies power to the LED module through the power output end.

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