Boost lighting drive circuit and LED lighting device

Abstract

The utility model discloses a boost illumination driving circuit. The boost illumination driving circuit comprises an inductor, a switch element, a controller and an LED light-emitting element. The input end of the inductor is connected with the voltage input end of the illumination driving circuit, the output end of the inductor is connected to the common end between the input end of the LED light-emitting element and the input end of the switch element, and the output end of the LED light-emitting element is connected with the common ground end of the illumination driving circuit. The control end of the switch element is connected with the external transistor connection pin of the controller, and the output end of the switch element is connected with the common ground end of the illumination driving circuit. The input end of the controller is connected between the voltage input end and the inductor input end. When the switch element is turned off, the voltage at two ends of the LED light-emitting element is boosted and is greater than the input voltage through the input voltage and the voltage at two ends of the inductor. The LED light-emitting element is used for replacing a fly-wheel diode in a traditional booster circuit, energy loss of the fly-wheel diode in the booster circuit is avoided, and the use efficiency of the power supply is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, and particularly relates to a boost lighting driving circuit and an LED lighting device. BACKGROUND

[0002] Voltage matching is a key technology in lighting circuits. Its purpose is at least as follows:

[0003] 1. Ensure normal operation of lighting equipment. Each lighting equipment has its rated voltage range, which is the premise of normal operation of the lighting equipment. If the actual voltage is higher or lower than the rated voltage of the equipment, it may cause abnormal operation of the lighting equipment, or even damage.

[0004] 2. Improve the service life of lighting equipment. Voltage mismatch not only affects the normal operation of lighting equipment, but also accelerates the aging process of lighting equipment and shortens its service life. For example, if the actual voltage is higher than the rated voltage of the equipment, the internal components of the lighting equipment will be subjected to excessive current and voltage impact, resulting in component damage or performance degradation. Conversely, if the actual voltage is lower than the rated voltage of the equipment, the lighting equipment may not work properly, and the components may also be in a low-voltage state for a long time, accelerating their aging.

[0005] 3. Ensure circuit safety. Voltage mismatch may also cause circuit safety problems. When the actual voltage is higher than the rated voltage of the lighting equipment, it may cause overheating, short circuit or fire of the equipment, etc. This not only damages the equipment, but also poses a threat to personal safety.

[0006] As can be seen, voltage matching is very important in lighting circuits. It not only ensures normal operation of the equipment, improves the service life of the equipment and ensures the safety of the circuit, but also improves energy efficiency and energy saving effect, and meets relevant standards and specifications. CONTENT OF THE INVENTION

[0007] The present application provides a boost lighting driving circuit to solve the problem of low circuit efficiency caused by the voltage drop of the freewheeling diode itself and the loss of the switching element caused by the reverse recovery of the freewheeling diode in the existing boost circuit.

[0008] The application provides a boost lighting drive circuit, comprising an inductor, a switching element, a controller and an LED light emitting element. The inductor input end is connected with the voltage input end of the boost lighting drive circuit, the inductor output end is connected with the common end between the input end of the LED light emitting element and the input end of the switching element, and the output end of the LED light emitting element is connected with the common ground end of the boost lighting drive circuit. The control end of the switching element is connected with the external transistor connection pin of the controller, and the output end of the switching element is connected with the common ground end of the boost lighting drive circuit. The input end of the controller is connected between the voltage input end and the inductor input end. When the switching element is turned off, the input voltage and the voltage between the inductor are used to boost the voltage between the LED light emitting element, and the voltage is greater than the input voltage.

[0009] Optionally, the boost lighting drive circuit further comprises a voltage dividing circuit, which comprises a first resistor and a second resistor. The input end of the first resistor is connected with the output end of the LED light emitting element, and the output end of the first resistor is connected with the input end of the second resistor. The output end of the second resistor is connected with the common ground end GND of the boost lighting drive circuit. The output voltage feedback pin of the controller is connected between the output end of the first resistor and the input end of the second resistor.

[0010] Optionally, the boost lighting drive circuit further comprises an input capacitor. The output end of the input capacitor is connected between the input voltage and the inductor, and the input end of the input capacitor is connected with the common ground end of the boost lighting drive circuit.

[0011] Optionally, the boost lighting drive circuit further comprises a current detection circuit, which comprises a third resistor. The input end of the third resistor is connected with the output end of the LED light emitting element, the output end of the third resistor is connected with the common ground end of the boost lighting drive circuit, and the input end of the third resistor is further connected with the current sampling pin of the controller.

[0012] Optionally, the input end of the controller comprises a power supply pin VDD and an enable control pin EN, which are respectively connected between the voltage input end and the inductor input end.

[0013] Optionally, the boost lighting drive circuit comprises a fourth resistor. The input end of the fourth resistor is connected between the control end of the switching element and the external transistor connection pin of the controller, and the output end of the fourth resistor is connected with the common ground end of the boost lighting drive circuit.

[0014] Optionally, the boost lighting drive circuit comprises an eighth resistor. The input end of the eighth resistor is connected with the enable control pin of the controller, and the output end of the eighth resistor is connected with the common ground end of the boost lighting drive circuit.

[0015] Optionally, the LED lighting device further comprises a dimming driving circuit. The dimming driving circuit comprises a filter circuit and a control unit. The filter circuit comprises a sixth resistor, a seventh resistor and a first capacitor. The input end of the sixth resistor is connected to the output end of the LED light emitting element and the common end of the current sampling pin of the controller, the output end of the sixth resistor is connected to the input end of the seventh resistor, and the output end of the seventh resistor is connected to the control unit. The input end of the first capacitor is connected between the output end of the sixth resistor and the input end of the seventh resistor, and the output end of the first capacitor is connected to the common ground end of the boost lighting driving circuit. The control unit is a single-chip microcomputer, which guides the controller to adjust the current by outputting a PWM waveform, so as to control the brightness of the LED light emitting element.

[0016] Optionally, the switching element is a field effect transistor with low on-resistance.

[0017] The application further provides another LED lighting device comprising the above boost lighting driving circuit.

[0018] By using the LED light emitting element to replace the freewheeling diode in the conventional boost circuit, on one hand, the energy loss on the original freewheeling diode can be reduced, so that the energy loss of the non-energy consumption end in the circuit loop is reduced, thereby improving the circuit efficiency and the use efficiency of the power supply. On the other hand, the use of the freewheeling diode and the output capacitor in the conventional boost circuit is reduced, so that the number of components in the circuit is reduced, and the circuit structure is simplified. At the same time, the reduction of components in the circuit brings convenience to the layout design of the printed circuit board, which is conducive to the layout optimization of the printed circuit board.

[0019] The LED boost lighting driving circuit of the embodiment of the application can freely set the limiting current. The output current is limited by connecting a current detection resistor between the current sampling pin of the controller and the ground pin, so as to limit the energy of the entire circuit loop, thereby limiting the maximum brightness of the LED light emitting element. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a circuit schematic diagram of a boost lighting driving circuit provided by the application.

[0021] Figure 2 is a structural schematic diagram of an embodiment of the boost lighting driving circuit provided by the application. DETAILED DESCRIPTION

[0022] In the following description, many specific details are set forth in order to provide a thorough understanding of the application. However, the application can be practiced without the specific details set forth in this description, in other manners that are consistent with the spirit of the application. Those skilled in the art can make similar substitutions to those disclosed in the following without departing from the scope of the application, and therefore the application is not limited to the specific implementations disclosed below.

[0023] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting thereof. Descriptions such as "a", "first", and "second" are used merely to distinguish one type of information from another type of information, and do not imply a quantity or a sequence order.

[0024] Based on the above background art, the present application concept is derived from how to avoid the problem of circuit energy consumption and low use efficiency in the scenario where the voltage at the output end of the LED light emitting element matches the voltage across the LED light emitting element.

[0025] In the prior art, there are three common variable voltage circuits: current-limiting resistor step-down circuit, DCDC_Buck step-down circuit and DCDC_Boost step-up circuit. Among them, in the current-limiting resistor step-down circuit, assuming that the current is a ternary polymer lithium battery, the battery voltage is 3.7V, the output current is 1A, and the current-limiting resistor is 1Ω. According to Ohm's law 1Ω*1A=1W, it means that 1W of energy will be lost on the current-limiting resistor, a total of 3.7V*1A=3.7W of energy, 1W / 3.7W=0.27, so it can be determined that 27% of the energy will be lost during current transmission. Therefore, in the case of large energy consumption in the current-limiting resistor, it will inevitably lead to a decrease in the use efficiency of the power supply. In the DCDC_Buck step-down circuit and the DCDC_Boost step-up circuit, when there is a large current in the circuit, the components in the circuit, such as resistors, freewheeling diodes, capacitors, etc., will produce a certain voltage drop when conducting, such as the freewheeling diode which usually produces a voltage drop of at least 0.3V, which will cause part of the electrical energy to be lost in the form of heat, thereby reducing the efficiency of the circuit. This loss is usually referred to as conduction loss. On the other hand, if the reverse recovery time of the freewheeling diode is long, the residual charge in the freewheeling diode may be discharged through the switching element when the switching element is turned on, thereby generating additional switching loss, which also reduces the efficiency of the circuit.

[0026] Based on the above problems in the prior art, the present application provides a step-up lighting driving circuit, which removes the freewheeling diode in the step-up lighting driving circuit and uses the set LED light emitting diode (also referred to as a light emitting element or a load) to realize the function of the freewheeling diode in the Boost step-up circuit. The LED light emitting diode not only can replace the freewheeling diode to realize the function of voltage matching, but also can realize the lighting function of the LED light emitting diode as a load. Therefore, compared with the existing step-up lighting driving circuit, the step-up lighting driving circuit provided by the present application avoids the problem of reducing the efficiency of the circuit caused by the circuit loss due to the existence of the freewheeling diode.

[0027] The following will be described in conjunction withFigure 1 This application provides a detailed description of the circuit principle of a boost lighting driver circuit.

[0028] Figure 1 The diagram shows the circuit schematic of the boost circuit in a boost lighting driver circuit provided in this application. Figure 1 As shown, the boost lighting driver circuit provided in this application can be used to achieve lighting using LEDs as light-emitting elements. Specifically, the boost lighting driver circuit may include: an inductor L, a light-emitting element D, a switching element NMOS, and a controller U. The switching element NMOS is a field-effect transistor, and in this embodiment, it is an N-channel enhancement-mode metal-oxide-semiconductor field-effect transistor. The controller U is a boost-type DC / DC controller. The LED light-emitting element is a light-emitting diode, which may include an LED array composed of multiple LED beads.

[0029] The inductor L input terminal is connected to the voltage input terminal V of the boost lighting driver circuit. IN Connections: The output terminal of the inductor L is connected to the common terminal between the input terminal of the LED light-emitting element D and the input terminal of the switching element NMOS; the output terminal of the LED light-emitting element D is connected to the common ground terminal GND of the boost lighting driver circuit; the control terminal of the switching element NMOS is connected to the external transistor connection pin EXT of the controller U; the output terminal of the switching element NMOS is connected to the common ground terminal GND of the boost lighting driver circuit; the input terminal of the controller U is connected to the voltage input terminal V. IN A boost lighting driver circuit is thus formed between the input terminal of the inductor L and the input terminal. In this boost lighting driver circuit, when the switching element is turned off, the voltage across the LED light-emitting element will be boosted due to the input voltage and the voltage across the inductor, and will be greater than the input voltage. The specific working principle is as follows:

[0030] When the input voltage V IN When power is supplied to the LED boost lighting driver circuit, the controller U starts working. Current enters from the input terminal of inductor L and flows out from the output terminal of inductor L. The controller U controls the voltage at the gate (control terminal) of the NMOS switching element to exceed the threshold voltage, thus turning the NMOS switching element on. At this time, a conductive channel is formed between the drain and source of the NMOS switching element, and current flows from the output terminal (drain) of the NMOS switching element to ground, thereby forming a closed loop. The input voltage V... INCharging the inductor L. When the switch element NMOS is in the on state, due to the unidirectional conductivity of the LED light emitting element, the LED light emitting element is in the off state, i.e. not working. At the same time, because the switch element NMOS is in the on state, the input voltage charges the inductor L, i.e. the current in the inductor L increases linearly, and the energy stored in the inductor also increases. The induced electromotive force of the inductor is "+" at the input end and "-" at the output end.

[0031] When the input voltage V IN When the LED boost lighting drive circuit is powered, the controller U starts to work. When the controller U controls the voltage at the control end (i.e. the gate) of the switch element NMOS to be less than the threshold voltage, the switch element NMOS is in the off state, the current enters from the input end of the inductor L, flows out from the output end of the inductor L, and enters the input end of the LED light emitting element D, and then enters the ground through the output end of the LED light emitting element D, forming a closed loop. At this time, due to the fact that the switch element NMOS is in the on state, the energy stored in the inductor L, and the self-induction effect of the inductor after the switch element NMOS is turned off, the voltage across the LED light emitting element D is the superposition of the input voltage and the voltage of the inductor L, i.e. the voltage across the LED light emitting element D is higher than the input voltage, thereby realizing the boost function of the LED light emitting element D, and achieving the purpose of matching the input voltage and the voltage across the LED light emitting element D. At the same time, because of the boost function, the normal lighting function of the LED light emitting element D is also ensured.

[0032] As can be understood from the above, the boost lighting drive circuit provided by the present application removes the freewheeling diode in the existing boost circuit and the capacitor connected to the output end of the freewheeling diode, thereby reducing the freewheeling diode and the capacitor connected to the output end of the freewheeling diode in the boost lighting drive circuit of the present application. Based on the cooperation of the light emitting diode, the switch element and the inductor in the boost lighting drive circuit provided by the present application, the boost control can still be realized, and the LED light emitting element can not only serve as one of the components for realizing the boost function in the boost circuit, but also realize the lighting function.

[0033] In the process of executing the above functions, the LED light-emitting element can avoid the problem of reduced circuit efficiency caused by energy loss of the freewheeling diode in the prior art. For electronic components in the circuit, some components have energy loss problems. In the boost lighting driving circuit provided by the application, the LED light-emitting element can emit the energy released by itself in the form of photons, thereby realizing energy conversion, i.e., conversion from electrical energy to optical energy, and further realizing the lighting function. Compared with the freewheeling diode, which loses a lot of energy in the process of realizing boost, the LED light-emitting element can utilize the energy released by itself to realize lighting after replacing the freewheeling diode, thereby reducing energy loss. Therefore, the circuit efficiency of the boost lighting driving circuit can be improved, and the problem of reduced circuit efficiency caused by energy loss of the freewheeling diode can be effectively avoided.

[0034] The boost lighting driving circuit provided by the application removes the freewheeling diode in the existing boost circuit and the capacitor connected to the output end of the freewheeling diode, so that the boost lighting driving circuit has fewer components, the circuit design is more simple, the energy loss is reduced, and the circuit efficiency is improved. In other words, in the boost lighting driving circuit provided by the application, the LED light-emitting element not only bears the load function but also bears the boost function in the boost circuit. The energy loss of the boost lighting driving circuit is also reduced due to the reduction of components, thereby making the entire circuit more efficient.

[0035] Based on the above, the embodiment can further include an input capacitor C IN , an output end of the input capacitor C IN is connected between the input voltage and the inductor L, and an input end of the input capacitor C IN is connected to the common ground end of the boost lighting driving circuit. The input capacitor C IN can improve the circuit efficiency by reducing the power impedance and input current averaging. In the embodiment, the input voltage can be provided by a battery or commercial power.

[0036] To protect the stability and reliability of the boost lighting driving circuit, the boost lighting driving circuit provided by the application can further include a voltage dividing circuit. In the embodiment, the voltage dividing circuit includes a first resistor R1 and a second resistor R2.

[0037] An input end of the first resistor R1 is connected to an output end of the LED light-emitting element D, an output end of the first resistor R1 is connected to an input end of the second resistor R2, an output end of the second resistor R2 is connected to the common ground end of the boost lighting driving circuit, and an output voltage feedback pin of the controller is connected between the output end of the first resistor R1 and the input end of the second resistor R2.

[0038] The output voltage feedback pin FB of the step-up DC / DC controller U detects the output voltage by detecting the voltage of the second resistor R2, V OUT The output voltage Vout can be calculated according to the following formula:

[0039]

[0040] Based on the above, in the embodiment, the controller U can be a step-up DC / DC controller U. Specifically, the step-up DC / DC controller U can include a controller power supply pin VDD, an enable control pin EN, a ground pin VSS, a current sampling pin VSE, an output voltage feedback pin FB, and an external transistor connection pin EXT.

[0041] The power supply pin VDD is connected to the input end of the input capacitor C IN , the input end of the inductor L, the input voltage, and the common end of the enable control pin EN. The power supply pin VDD can be used to power the step-up DC / DC controller U.

[0042] The power supply pin and the enable control pin EN are connected between the voltage input end and the inductor input end, respectively. Based on the above, it can be understood that the enable control pin EN is connected to the input end of the input capacitor C IN , the input end of the inductor L, the input voltage, and the common end of the controller power supply pin VDD. The enable control pin EN is used to control the conduction and shutdown of the input power supply of the step-up DC / DC controller U. When conducting, the step-up DC / DC controller U is powered on and in normal working state. When turned off, the step-up DC / DC controller U is in standby state. When the enable control pin EN is set to "L" potential, the voltage of the external transistor connection pin EXT is fixed at 0V, and the external transistor and internal circuit stop working, so the consumption current can be greatly suppressed. When using the EN function in a floating state, it will cause an increase in consumption current.

[0043] The ground pin VSS can be grounded and used as a reference ground for the step-up DC / DC controller U.

[0044] The current sampling pin VSE is connected to the output end of the LED light emitting element D and is used to detect the output current.

[0045] The output voltage feedback pin FB is connected between the first resistor output end and the second resistor input end, and is used to detect and feedback the output voltage.

[0046] The external transistor connection pin EXT is connected to the control end of the switching element NMOS. The external transistor connection pin EXT is used to control the conduction and shutdown of the switching element NMOS.

[0047] To ensure the stability and safety of the boost lighting driving circuit, the current can be detected by the current detection circuit, so as to determine whether the boost lighting driving circuit has a fault or optimize the circuit performance, and therefore further comprises a current detection circuit comprising a third resistor R3, wherein the input end of the third resistor R3 is connected with the output end of the LED light emitting element D, the output end of the third resistor R3 is connected with the common ground end of the boost lighting driving circuit, and the input end of the third resistor R3 is further connected with the current sampling pin of the controller.

[0048] The boost DC / DC controller U limits the output current by connecting a current detection resistor (R SENSE ) between the current sampling pin VSE and the ground pin VSS. Figure 1 In this embodiment, the third resistor R3 is the current detection resistor (R SENSE ). When the current sampling pin VSE reaches the typical value of the current limit detection voltage (V SENSE ), the voltage value is maintained by the current limit amplifier inside the boost DC / DC controller U. Therefore, the output current (I OUT ) can be kept stable without being affected by the output LED light emitting element. The limit current (I LIM ) can limit the output current (I OUT ), limit the energy of the entire circuit loop, and limit the maximum brightness of the LED light emitting element. The limit current (I SENSE ) can be set by R LIM . The limit current (I SENSE ) can be calculated according to the following formula:

[0049]

[0050] If the limit current detection voltage (V SENSE ) is lower than the typical value due to the decrease of the LED light emitting element current, the current limit state will automatically recover to the normal state.

[0051] In this embodiment, the boost lighting driving circuit is used to switch the working state and the sleep state of the LED light emitting element. When the switch element NMOS is turned on, the LED light emitting element is short-circuited, the LED lamp bead is extinguished, and the LED light emitting element is in the sleep state. When the switch element NMOS is turned off, the LED light emitting element is lit and in the working state.

[0052] The input end of the inductor L is connected with the input capacitor C INThe common terminal of the input pin, input voltage, power supply pin VDD, and enable control pin EN of the inductor L is connected. The output terminal of the inductor L is connected to the common terminal of the input pin of the LED light-emitting element D and the input pin of the switching element NMOS. When the switching element NMOS is turned on, the input voltage charges the inductor L, and the LED light-emitting element is short-circuited. Current enters the inductor L from its input terminal, flows out of the inductor L from its output terminal, then enters the switching element NMOS from its input terminal, and flows to ground from its output terminal, forming a closed loop. After the switching element NMOS is turned on, the current in the inductor L increases linearly, and the energy stored in the inductor L also increases (i.e., the inductor begins to store energy), converting electrical energy into magnetic field energy. During this process, the current gradually increases, and the magnetic flux inside the inductor L also increases accordingly. The induced electromotive force of the inductor L is positive at the input terminal and negative at the output terminal. When the NMOS switching element is turned off, current flows from the input terminal of inductor L to the output terminal of inductor L, then into the input terminal of LED light-emitting element D, and finally from the output terminal of LED light-emitting element D through the third resistor R3 to ground, forming a closed loop. After the NMOS switching element is turned off, due to the self-inductance of inductor L, the current in inductor L cannot change abruptly. Instead, it gradually converts the released magnetic field energy into electric field energy and transfers it to the input terminal of LED light-emitting element D. Therefore, an induced voltage is generated across inductor L, with the input terminal being "-" and the output terminal being "+". At this time, the voltage across LED light-emitting element D is the superposition of the input voltage and the induced voltage generated by inductor L, meaning the voltage across LED light-emitting element D is higher than the input voltage. This achieves the purpose of using a boost lighting driver circuit to boost the voltage and match the input voltage with the voltage across LED light-emitting element D.

[0053] The input terminal of the NMOS switching element is connected to the common terminal of the output terminal of the inductor L and the input terminal of the LED light-emitting element D. The output terminal of the NMOS switching element is grounded, and the control terminal of the NMOS switching element is connected to the external transistor connection pin EXT. The boost DC / DC controller U can control the switching element NMOS to turn on and off through the external transistor connection pin EXT. The boost lighting drive circuit of the embodiments of this application uses an N-channel enhancement-mode metal-oxide-semiconductor field-effect transistor (NMOS) with low on-resistance, which is suitable for application circuits requiring high efficiency and high output current. Preferably, an ON resistor (R) is used. ON Low input capacity (C) ISS Smaller N-channel enhancement-mode metal-oxide-semiconductor field-effect transistors.

[0054] The input terminal of LED light-emitting element D is connected to the common terminal of the output terminal of inductor L and the input terminal of the switching element NMOS. The output terminal is connected to the common terminal of the input terminals of the first resistor R1, the third resistor R3, and the current sampling pin VSE. LED light-emitting element D, i.e., LED light-emitting element, is used for lighting.

[0055] The controller U continuously samples the voltage at its output voltage feedback pin FB. Based on the sampled voltage at FB, the controller U controls the switching element NMOS to turn on and off. When the voltage at FB is less than the controller U's internal reference voltage, the NMOS is turned off. When the voltage at FB reaches the controller U's internal reference voltage, the NMOS is turned on. By periodically controlling the on / off state of the N-channel enhancement-mode metal-oxide-semiconductor field-effect transistor (NMOS), pulse modulation of the input voltage is achieved, thereby realizing voltage conversion and maintaining a stable average output voltage across the LED light-emitting element D.

[0056] The following is combined Figure 2 The following describes in detail the exemplary embodiments of this application. Figure 2 This is a schematic diagram of a boost lighting driver circuit embodiment provided in this application.

[0057] like Figure 2 As shown, the boost lighting driver circuit provided in this application can be used to achieve lighting using LEDs as light-emitting elements. Specifically, the boost lighting driver circuit may include: an inductor L, a light-emitting element D, a switching element NMOS, and a controller U. The switching element NMOS is a field-effect transistor, and in this embodiment, it is an N-channel enhancement-mode metal-oxide-semiconductor field-effect transistor. The controller U is a boost-type DC / DC controller. The LED light-emitting element is a light-emitting diode, which may include an LED array composed of multiple LED beads.

[0058] The inductor L input terminal is connected to the voltage input terminal V of the boost lighting driver circuit. IN Connections: The output terminal of the inductor L is connected to the common terminal between the input terminal of the LED light-emitting element D and the input terminal of the switching element NMOS; the output terminal of the LED light-emitting element D is connected to the common ground terminal GND of the boost lighting driver circuit; the control terminal of the switching element NMOS is connected to the external transistor connection pin EXT of the controller U; the output terminal of the switching element NMOS is connected to the common ground terminal GND of the boost lighting driver circuit; the power supply pin of the controller U is connected to the voltage input terminal V. INThus, the boost lighting driving circuit is formed. In the boost lighting driving circuit, when the switch element NMOS is turned off, the voltage across the LED light emitting element is boosted due to the input voltage and the voltage across the inductor, and is greater than the input voltage. The specific working principle can be referred to the working principle of the boost lighting driving circuit shown in Figure 1 and will not be described in detail here.

[0059] Based on the above, in the embodiment, the controller U can be a boost type DC / DC controller U. Specifically, the boost type DC / DC controller U can include a controller power supply pin VDD, a current sampling pin VSE, an output voltage feedback pin FB, an external transistor connection pin EXT, a ground pin VSS, and an enable control pin EN.

[0060] The power supply pin VDD is connected with the input voltage V IN . The power supply pin VDD can be used to power the boost type DC / DC controller U.

[0061] The current sampling pin VSE is connected with the output end of the LED light emitting element D, and is used to detect the output current.

[0062] The output voltage feedback pin FB is connected between the output end of the first resistor and the input end of the second resistor, and is used to detect and feedback the output voltage.

[0063] The external transistor connection pin EXT is connected with the control end of the switch element NMOS. The external transistor connection pin EXT is used to control the conduction and turn-off of the switch element NMOS.

[0064] The ground pin VSS can be grounded and can be used as a reference ground of the boost type DC / DC controller U.

[0065] The enable control pin EN is connected with the LED EN. The enable control pin EN is used to control the conduction and turn-off of the input power supply of the boost type DC / DC controller U. When it is turned on, the boost type DC / DC controller U is connected to the power supply and is in a normal working state. When it is turned off, the boost type DC / DC controller U is in a standby state. When the enable control pin EN is set to "L" potential, the voltage of the external transistor connection pin EXT is fixed to 0V, and the external transistor and the internal circuit stop working, so the consumption current can be greatly suppressed. When the EN function is used in a floating state, the consumption current will increase.

[0066] In this embodiment, a boost lighting driver circuit is used to switch the LED light-emitting element between its working and sleep states. When the NMOS switching element is turned on, the LED light-emitting element is short-circuited, the LED is off, and the LED light-emitting element is in a sleep state. When the NMOS switching element is turned off, the LED light-emitting element is lit and is in the working state.

[0067] The input terminal of inductor L and the input capacitor C IN The input terminal and input voltage V IN The common terminal of the inductor L is connected, and the output terminal of the inductor L is connected to the common terminal of the input terminal of the LED light-emitting element D and the input terminal of the switching element NMOS. In this embodiment, the function of the inductor L is as follows: Figure 1 The inductor L in the boost lighting driver circuit shown has the same function, which will not be described in detail here.

[0068] The input terminal of the NMOS switching element is connected to the common terminal of the output terminal of the inductor L and the input terminal of the LED light-emitting element D. The output terminal of the NMOS switching element is grounded, and the control terminal of the NMOS switching element is connected to the external transistor connection pin EXT of the controller U. In this embodiment, the function of the NMOS switching element is as follows: Figure 1 The NMOS switching element in the boost lighting drive circuit shown has the same function, and will not be described in detail here.

[0069] The input terminal of LED light-emitting element D is connected to the common terminal of the output terminal of inductor L and the input terminal of the switching element NMOS. The output terminal is connected to the common terminal of the first resistor R1, the third resistor R3, the fifth resistor R5, and the current sampling pin VSE. LED light-emitting element D, i.e., LED light-emitting element, is used for lighting.

[0070] Based on the above, this embodiment may further include: an input capacitor C IN The input capacitor C IN The output terminal is connected between the input voltage and the inductor L, and the input capacitor C IN The input terminal is connected to the common ground terminal of the boost lighting driver circuit. Input capacitor C IN Circuit efficiency can be improved by reducing power supply impedance and averaging input current. In this embodiment, the input voltage can be provided by a battery or by AC power.

[0071] To protect the stability and reliability of the boost lighting driver circuit, this application provides a boost lighting driver circuit that may further include a voltage divider circuit. In this embodiment, the voltage divider circuit includes a first resistor R1 and a second resistor R2.

[0072] The input end of the first resistor R1 is connected with the output end of the LED light emitting element D, and the output end of the first resistor R1 is connected with the input end of the second resistor R2; the output end of the second resistor R2 is connected with the common ground end of the boost lighting driving circuit; the output voltage feedback pin of the controller is connected between the output end of the first resistor R1 and the input end of the second resistor R2.

[0073] The output voltage feedback pin FB of the boost DC / DC controller U detects the output voltage by detecting the voltage of the second resistor R2, V OUT The output voltage Vout of the boost lighting driving circuit can be calculated by the following formula:

[0074]

[0075] In order to ensure the stability and safety of the boost lighting driving circuit, the current detection circuit can be used to detect the current, so as to judge whether the boost lighting driving circuit has a fault or optimize the circuit performance, and therefore, the boost lighting driving circuit further comprises a current detection circuit. In the embodiment, the current detection circuit comprises a third resistor R3 and a fifth resistor R5.

[0076] In order to ensure the stability and safety of the boost lighting driving circuit, the current detection circuit can be used to detect the current, so as to judge whether the boost lighting driving circuit has a fault or optimize the circuit performance, and therefore, the boost lighting driving circuit further comprises a current detection circuit. In the embodiment, the current detection circuit comprises a third resistor R3 and a fifth resistor R5. The input end of the third resistor R3 is connected with the common end of the output end of the LED light emitting element D, the input end of the first resistor R1 and the input end of the fifth resistor R5, and the output end of the third resistor R3 is grounded. The input end of the fifth resistor R5 is connected with the common end of the output end of the LED light emitting element D, the input end of the first resistor R1 and the input end of the third resistor R3, and the output end of the fifth resistor R5 is connected with the common end of the input end of the sixth resistor R6 and the current sampling pin VSE. In the embodiment, the current detection circuit has the same effect as the current detection circuit shown in Figure 1 The current detection circuit has the same effect as the current detection circuit shown in

[0077] The input end of the fourth resistor R4 is connected with the common end of the control end of the switch element NMOS and the external transistor connection pin EXT, and the output end of the fourth resistor R4 is grounded. The fourth resistor R4 is used to prevent the uncontrolled conduction and turn-off of the switch element NMOS caused by the noise signal, improve the reliability and stability of the switch element NMOS, and prevent the damage of the switch element NMOS caused by the shutdown of the boost DC / DC controller U.

[0078] As shown in Figure 2 The boost lighting driving circuit further comprises a dimming driving circuit. The dimming driving circuit comprises an RC filter circuit and a control unit.

[0079] The RC filter circuit comprises a sixth resistor R6, a seventh resistor R7 and a first capacitor C1. The control unit can be a single-chip microcomputer.

[0080] An input end of the sixth resistor R6 is connected to a common end of an output end of the fifth resistor R5 and a current sampling pin VSE, and an output end of the sixth resistor R6 is connected to a common end of an input end of the seventh resistor R7 and an input end of the first capacitor C1.

[0081] An input end of the seventh resistor R7 is connected to a common end of an output end of the sixth resistor R6 and the input end of the first capacitor C1, and an output end of the seventh resistor R7 is connected to the control unit of the light-emitting element of the dimming circuit.

[0082] An input end of the first capacitor C1 is connected to a common end of the output end of the sixth resistor R6 and the input end of the seventh resistor R7, and an output end of the first capacitor C1 is grounded. The sixth resistor R6, the seventh resistor R7 and the first capacitor C1 together constitute an RC filter circuit.

[0083] The single-chip microcomputer outputs a pulse width modulation (PWM) waveform, and the RC filter circuit filters the PWM waveform output by the single-chip microcomputer to make it smooth into a stable direct current (DC) output waveform. The DC output waveform after the RC filter circuit influences the feedback voltage of the boost DC / DC controller U through the current sampling pin VSE, thereby guiding the boost DC / DC controller U to adjust the current, achieving the purpose of dimming the LED light-emitting element.

[0084] An input end of the eighth resistor R8 is connected to a common end of an enable control pin EN and an LED EN, and an output end of the eighth resistor R8 is grounded. The LED EN is connected to a driving device of the controller U, and the LED EN can be connected to the single-chip microcomputer. When the single-chip microcomputer gives a high-level signal, the boost DC / DC controller U is turned on to be in a normal working state. When the single-chip microcomputer gives a low-level signal, the boost DC / DC controller U is turned off to be in a standby state. The eighth resistor R8 is used to prevent noise signals, and when there is no signal input, the enable control pin EN is in a standby state, improving the reliability and stability of the boost DC / DC controller U.

[0085] An input end of the second capacitor C2 is connected to a power supply pin VDD, and an output end of the second capacitor C2 is grounded. The second capacitor C2 is used to improve the stability of the input voltage for powering the boost DC / DC controller U.

[0086] The working state of the LED boost lighting driving circuit (for example, the LED boost lighting driving circuit as shown in Figure 2 Fig. 1) of the embodiment of the present application is the same as Figure 1The working states of the illustrated boost lighting driving circuits are the same, and will not be described in detail here.

[0087] The application also provides an LED lighting device comprising the above boost lighting driving circuit.

[0088] As the use of the LED light emitting element replaces the freewheeling diode in the conventional boost circuit, the use of the freewheeling diode and the output capacitor in the conventional boost circuit is reduced, so that the number of components in the circuit is reduced. This change not only simplifies the circuit structure, but also reduces the energy loss on the freewheeling diode, so that the energy loss of the non-energy consumption end in the circuit loop is reduced, thereby realizing the improvement of the circuit efficiency, and the use efficiency of the power supply is also improved.

[0089] At the same time, the reduction of components in the circuit facilitates the layout design of the printed circuit board, and is conducive to the layout optimization of the printed circuit board.

[0090] The boost lighting driving circuit adopting the embodiment of the application can freely set the limiting current. The output current is limited by connecting a current detection resistor between the current sampling pin of the controller and the ground pin, the energy of the entire circuit loop is limited, and thus the maximum brightness of the LED light emitting element is limited.

[0091] Although the preferred embodiments of the embodiments of the application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the application.

[0092] Finally, it should also be noted that in this document, relational terms such as first and second and the like can only be used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations exist in any such actual relationship or order. Moreover, the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed or inherent to such a process, method, article or terminal device. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or terminal device including the element.

[0093] Although the present application is disclosed with reference to the preferred embodiments above, it is not intended to limit the present application, and any person skilled in the art who learns the present application can make possible changes and modifications without departing from the spirit and scope of the present application, and the protection scope of the present application should be defined by the scope of the claims of the present application.

Claims

1. A boost lighting drive circuit, characterized by, Comprising: an inductor, a switching element, a controller and an LED light emitting element; the inductor input end is connected with the voltage input end of the step-up lighting driving circuit; the inductor output end is connected with the common end between the input end of the LED light emitting element and the switching element input end; the output end of the LED light emitting element is connected with the common ground end of the step-up lighting driving circuit; the control end of the switching element is connected with the external transistor connection pin of the controller; the output end of the switching element is connected with the common ground end of the step-up lighting driving circuit; the input end of the controller is connected between the voltage input end and the inductor input end; when the switching element is off, the input voltage and the voltage across the inductor control the voltage across the LED light emitting element to be boosted and greater than the input voltage.

2. The boost lighting drive circuit of claim 1, wherein Further comprising: a voltage dividing circuit; the voltage dividing circuit comprises a first resistor and a second resistor; the input end of the first resistor is connected with the output end of the LED light emitting element, the output end of the first resistor is connected with the input end of the second resistor, the output end of the second resistor is connected with the common ground end of the step-up lighting driving circuit, and the output end of the first resistor and the input end of the second resistor are connected with the output voltage feedback pin of the controller.

3. The boost lighting drive circuit of claim 1, wherein, Comprising: an input capacitor, the output end of the input capacitor is connected between the input voltage and the inductor, and the input end of the input capacitor is connected with the common ground end of the step-up lighting driving circuit.

4. The boost lighting drive circuit of claim 1, wherein, Further comprising: a current detection circuit, comprising a third resistor, the input end of the third resistor is connected with the output end of the LED light emitting element, the output end of the third resistor is connected with the common ground end of the step-up lighting driving circuit, and the input end of the third resistor is also connected with the current sampling pin of the controller.

5. The boost lighting drive circuit of claim 1, wherein, The input end of the controller comprises a power supply pin and an enable control pin, which are respectively connected between the voltage input end and the inductor input end.

6. The boost lighting drive circuit of claim 1, wherein, Comprising a fourth resistor, the input end of the fourth resistor is connected between the control end of the switching element and the external transistor connection pin of the controller, and the output end of the fourth resistor is connected with the common ground end of the step-up lighting driving circuit.

7. The boost lighting drive circuit of claim 1, wherein, Comprising an eighth resistor, the input end of the eighth resistor is connected with the enable control pin of the controller, and the output end of the eighth resistor is connected with the common ground end of the step-up lighting driving circuit.

8. The boost lighting drive circuit of claim 5, wherein, Further comprising a dimming driving circuit; the dimming driving circuit comprises a filter circuit and a control unit; the filter circuit comprises a sixth resistor, a seventh resistor and a first capacitor; the input end of the sixth resistor is connected with the common end of the output end of the LED light emitting element and the current sampling pin of the controller, the output end of the sixth resistor is connected with the input end of the seventh resistor, and the output end of the seventh resistor is connected with the control unit; the input end of the first capacitor is connected between the output end of the sixth resistor and the input end of the seventh resistor, and the output end of the first capacitor is connected with the common ground end of the step-up lighting driving circuit; The control unit is a single-chip microcomputer, which guides the controller to adjust the current by outputting a PWM waveform, thereby controlling the brightness of the LED light-emitting element.

9. The boost lighting drive circuit of claim 1, wherein, The switching element is a field effect transistor with low on-resistance.

10. An LED lighting device, characterized by The LED lighting device comprises the boost lighting drive circuit according to any one of claims 1-9.

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