Light source driving circuit and light source apparatus

Abstract

The present disclosure relates to a light source driving circuit, comprising a power module, a first load connection end, a second load connection end, a switch module, a constant current control module and a current sampling module; the current sampling module is connected in series in a load driving loop, and a first end of the current sampling module connected with the switch module is a first sampling node; the constant current control module is connected with a controller, and the constant current control module receives and generates a switch driving signal according to a first pulse signal, a second pulse signal and a first sampling signal, and outputs the switch driving signal to a first controlled end of a first switch of the switch module, so as to trigger the first switch to turn on and make a load light source to be powered on and work in a constant current state, or trigger the first switch to turn off and make the load light source to be powered off and extinguished. The light source driving circuit, without using an integrated driving chip, combines conventional electronic components into a constant current control module, adjusts the amplitude of a pulse driving signal, so as to realize constant current driving of load light sources with different rated powers, and has wide adaptability.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of light source driving, and in particular to a light source driving circuit and a light source device. BACKGROUND

[0002] In the field of lighting, LED (Light-Emitting Diode) is gradually replacing traditional light sources such as incandescent lamps and fluorescent lamps as an energy-saving, environmentally friendly, long-life and small-volume light source product. In some special occasions, such as automobile LED light source driving or stage lighting driving, high-power LED light sources are needed, and high-power LED light sources need to be driven by a large current to be lit. In the LED dimming circuit driven by a large constant current, an integrated driving chip is usually used in combination with a synchronous buck (BUCK) power supply circuit to achieve constant current driving. However, in recent years, due to the shortage of integrated driving chips, the price of chips is getting higher and higher, which has made the implementation of the LED driving dimming circuit a difficult problem, increased the production cost, and seriously affected the production cycle of LED products.

[0003] Based on the above situation, some researchers try to use electronic circuits with conventional electronic components and conventional structures to achieve constant current driving of high-power LED light sources, such as sampling the current of the load circuit, and controlling the output of the driving current according to the size of the sampled current and a single pulse driving signal to achieve constant current driving.

[0004] The present disclosure found that if only the size of the sampled current and a single pulse driving signal are used to control the driving current, since the amplitude of the single pulse driving signal is constant, only LED light sources with a working current of a certain specific value or below can be driven to light up, and LED light sources with a larger working current cannot be driven to light up, such as a light source driving circuit with a working current of 7A cannot drive a light source with a working current greater than 7A to light up, which has the problems of less power adaptation of the light source and poor adaptability. SUMMARY

[0005] The present disclosure provides a light source driving circuit and a light source device, which can adaptively adjust the amplitude of the pulse driving signal to achieve constant current driving of loads with different rated powers without using an integrated driving chip, and has wide adaptability.

[0006] The technical solutions of the embodiments of the present disclosure are described below.

[0007] In a first aspect, the present disclosure provides a light source driving circuit, comprising:

[0008] a power supply module, a first load connection end, a second load connection end, a switch module, a constant current control module, and a current sampling module.

[0009] The first load connection end is used to connect to a first end of a load light source, and the second load connection end is used to connect to a second end of the load light source;

[0010] The switch module includes a first switch having a first signal terminal, a second signal terminal and a first controlled terminal;

[0011] When a load light source is connected between the first load connection terminal and the second load connection terminal, the output terminal of the power module, the first load connection terminal, the second load connection terminal, the first signal terminal of the switch module, the second signal terminal of the switch module, and the ground terminal of the power module are connected in sequence to form a load driving loop;

[0012] The current sampling module is connected in series in the load driving circuit, and the connection between the current sampling module and the first switch forms a first sampling node;

[0013] The constant current control module has a first sampling terminal, a first driving input terminal, a second driving input terminal and a current regulating terminal. The first sampling terminal of the constant current control module is connected to the first sampling node and is used to receive a first sampling signal. The first driving input terminal is used to be connected to the first pulse signal output terminal of the controller, and the second driving input terminal is used to be connected to the second pulse signal output terminal of the controller. The current regulating terminal is connected to the first controlled terminal of the switch module;

[0014] The constant current control module is used to receive the first pulse signal and the second pulse signal output by the controller, and receive the first sampling signal, and generate a switch drive signal according to the first pulse signal, the second pulse signal and the first sampling signal, and output it to the first controlled end of the first switch of the switch module, triggering the first switch to turn on so that the load light source is powered and operates in a constant current state, or triggering the first switch to turn off so that the load light source loses power and extinguishes.

[0015] In a second aspect, an embodiment of the present disclosure provides a light source device, including a controller, an LED light source, and a light source driving circuit as described in any one of the above embodiments;

[0016] The LED light source is connected in series to the light source driving circuit to form a load driving loop.

[0017] The controller is used to output a pulse signal to the light source driving circuit to control the LED light source to light up and operate in a constant current state or to turn it off.

[0018] In the above embodiment of the present disclosure, the load light source is powered by a power supply module. Without using an integrated driver chip, a constant current control module is formed by combining conventional electronic components. The constant current control module receives the first pulse signal and the second pulse signal sent by the controller, and controls the controlled end of the switch module in combination with the first sampling signal, that is, the amplitude and duty cycle of the drive signal and the sampling signal are combined to achieve constant current drive of the load light source. The brightness of the load light source can be determined according to the duty cycle of the pulse signal, and the operating current of the load light source can be determined according to the amplitude of the pulse signal. The amplitude of the pulse drive signal can be adaptively adjusted by the controller, and it can be backward compatible with load light sources of various operating currents to achieve constant current drive of load light sources with different rated powers, and has wide adaptability.

[0019] For better understanding and implementation, the present disclosure is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a structural block diagram of a light source driving circuit according to an embodiment of the present disclosure;

[0021] Figure 2 A circuit schematic diagram of a constant current control module according to an embodiment of the present disclosure;

[0022] Figure 3 A schematic diagram of an amplitude adaptation circuit according to an embodiment of the present disclosure;

[0023] Figure 4 A circuit schematic diagram of a constant voltage control module according to an embodiment of the present disclosure;

[0024] Figure 5 A schematic diagram of a reference voltage circuit according to an embodiment of the present disclosure;

[0025] Figure 6 A schematic diagram of a bias voltage source module according to an embodiment of the present disclosure;

[0026] Figure 7 A circuit schematic diagram of a voltage feedback circuit according to an embodiment of the present disclosure;

[0027] Figure 8 This is a circuit schematic diagram of a power module according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0029] It should be clear that the embodiments described are only a part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the embodiments of the present disclosure.

[0030] The terms used in the embodiments of the present disclosure are for the purpose of describing specific embodiments only and are not intended to limit the embodiments of the present disclosure. The singular forms "a," "the," and "the" used in the embodiments of the present disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0031] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are merely examples of devices and circuits consistent with some aspects of the present disclosure as detailed in the appended claims. In the description of the present disclosure, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances.

[0032] In addition, in the description of this disclosure, unless otherwise specified, "several" refers to two or more. "And / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0033] The present disclosure discloses a light source driving circuit that can be applied to high-power LED light source equipment. Without using an integrated driver chip, conventional electronic components are combined into various functional modules to achieve constant current drive of the LED load, which reduces the difficulty of implementing the LED driver circuit and reduces production costs.

[0034] The various parts of the embodiments of the present disclosure are described below in conjunction with the accompanying drawings.

[0035] In each embodiment of the present disclosure, in the driving of the LED light source load, the constant voltage function is: it can limit the maximum value of the output voltage, and ensure constant voltage and voltage-limited output when there is no load or light load, thereby ensuring the safety of the light source; the constant current function is: it can limit the maximum value of the output current and keep it constant, meeting the constant current working characteristics of the LED light source, and can ensure the consistency of the current passing through when the voltage of the light source itself changes slightly.

[0036] The present disclosure provides a light source driving circuit. Figure 1 , Figure 1 This is a structural block diagram of a light source driving circuit according to an embodiment of the present disclosure.

[0037] The light source driving circuit includes a power supply module 10 , a first load connection terminal 20 , a second load connection terminal 30 , a switch module 40 , a constant current control module 50 and a current sampling module 60 .

[0038] The first load connection terminal 20 is used to connect the first end of the load light source 70. If the first load connection terminal 20 is a DC current output terminal, the first end of the load light source 70 can be the positive pole of the load light source 70, otherwise it is the negative pole. The second load connection terminal 30 is used to connect the second end of the load light source 70. If the second load connection terminal 30 is a DC current ground terminal, the second end of the load light source 70 can be the negative pole of the load light source 70, otherwise it is the positive pole.

[0039] In this embodiment, the first end of the load light source 70 can be the positive pole of the load light source 70, and the first end of the load light source 70 is connected to the output end of the power module 10. The second end of the load light source 70 can be the negative pole of the load light source 70, and the second end of the load light source 70 can be connected to the reference ground GND through the switch module 40. The reference ground GND is connected to the ground terminal GND of the power module 10 so as to form a load driving loop when the load light source 70 is connected.

[0040] In this embodiment, the load light source 70 can be a high-power LED light source, that is, the current flowing through the load light source 70 is large. The load light source 70 can be a single LED lamp or an LED lamp string composed of multiple LED lamps connected in series, or it can be other light-emitting elements, such as LCD lamps, etc., which is not limited in this embodiment.

[0041] The switch module 40 includes a first switch having a first signal terminal 411, a second signal terminal 412, and a first controlled terminal 413. When the voltage at the first controlled terminal 413 of the first switch is greater than the turn-on voltage of the first switch, the first switch is turned on to connect the second signal terminal 412 to the first signal terminal 411. The first signal terminal 411 can be a signal input terminal, and the second signal terminal 412 can be a signal output terminal.

[0042] The first switch may be a field effect transistor, a transistor or other switching devices, which is not limited in this embodiment.

[0043] When a load light source 70 is connected between the first load connection terminal 20 and the second load connection terminal 30, and the first switch is turned on, the output end of the power module 10, the first load connection terminal 20, the load light source 70, the second load connection terminal 30, the first signal end 411 of the switch module 40, the second signal end 412 of the switch module 40, and the ground end GND of the power module 10 are connected in sequence to form a load driving circuit, so that the load light source 70 connected in series in the load driving circuit can be lit.

[0044] The current sampling module 60 is connected in series to the load drive circuit. Optionally, the first end of the current sampling module 60 connected to the switch module 40 may be a first sampling node. The first sampling node is used to connect to the constant current control module 50 to sample the drive current, thereby facilitating better constant current control of the drive current and achieving dimming. In other embodiments, the first sampling node may also be other nodes in the load drive circuit.

[0045] The current sampling module 60 can be a sampling resistor or other sampling element. The sampling resistor is connected in series in the load driving circuit. Specifically, the current sampling module 60 can be connected in series between the negative electrode of the load light source 70 and the ground terminal GND. In this embodiment, the current sampling module 60 is connected in series between the switch module 40 and the reference ground GND.

[0046] The constant current control module 50 has a first sampling terminal 501 , a first driving input terminal 502 (as in 1 , for transmitting ADIM signals), a second driving input terminal 503 (as in 1 , for transmitting PDIM signals) and a current regulating terminal 504 .

[0047] The first sampling terminal 501 of the constant current control module 50 is connected to the first sampling node and is used to sample the driving current of the load light source 70 and receive a first sampling signal. The first driving input terminal 502 of the constant current control module 50 is used to connect to the first pulse signal output terminal 801 of the controller 80. The second driving input terminal 503 of the constant current control module 50 is used to connect to the second pulse signal output terminal 802 of the controller 80. The current regulating terminal 504 of the constant current control module 50 is connected to the first controlled terminal 413 of the switch module 40 and is used to output a switch driving signal with a constant amplitude to the first controlled terminal 413 of the switch module 40.

[0048] The constant current control module 50 receives the first pulse signal (ADIM) and the second pulse signal (PDIM) output by the controller 80, and receives the first sampling signal. The constant current control module 50 processes the first sampling signal, the first pulse signal (ADIM) and the second pulse signal (PDIM) to obtain a switch drive signal and outputs it to the first controlled end 413 of the switch module 40 to trigger the switch module 40 to turn on or off, thereby realizing constant current drive of the load light source 70.

[0049] When the switch module 40 is turned on and works in the amplification area, the load light source 70 is connected in series in the load driving circuit, that is, the positive pole of the load light source 70 is connected to the output end of the power module 10, and the negative pole is grounded, and the load light source 70 is powered and lit. When the switch module 40 is turned off, the load driving circuit cannot be formed, the load light source 70 loses power and is in an off state. When the frequency of the switch module 40 being turned on and off reaches a certain value, the brightness adjustment of the load light source 70 can be achieved.

[0050] Since the first sampling signal is a current signal flowing through the load light source 70, this embodiment can adjust the switch drive signal according to the size of the current signal, combined with the first pulse signal for determining the voltage amplitude, and the second pulse signal for determining the duty cycle, so as to ensure that the current flowing through the load light source 70 is constant and realize constant current drive.

[0051] In this embodiment, the first pulse signal can be a pulse modulation signal ADIM with a controllable duty cycle, which can control the current amplitude of the LED drive to prevent the operating current of the load light source 40 from exceeding the preset rated operating current, causing damage to the light source and the driving circuit.

[0052] The duty cycle of the first pulse signal ADIM can be set by the inventor in software through the controller 50 according to actual circuit requirements. It can usually be set to a larger duty cycle in order to obtain a larger rated current value of the load light source. At any time, as long as the current value of the load light source 40 is less than the rated current value when it is working, the load light source 40 can be driven to light up without being damaged due to overcurrent. For example, the duty cycle of the first pulse signal ADIM can correspond to a rated operating current value of 13 amps, and the load light source 40 can be downwardly compatible with operating currents of 12 amps, 10 amps, 7 amps, etc., and has a wide adaptability.

[0053] The second pulse signal can be a pulse modulation signal PDIM with a controllable duty cycle, which can adjust the brightness of the load light source 70. The duty cycle of the second pulse signal can be set by the discloser in the software through the controller 50 according to the actual circuit requirements. The principle of brightness adjustment of the load light source 70 is as follows: within a unit time period, the longer the switch module 40 is on, the longer the load light source 70 is lit. When the on-frequency of the switch module 40 reaches a certain value, the visual effect presented is that the brightness of the load light source 70 is greater, the shorter the on-time of the switch module 40, the shorter the time the load light source 70 is lit, and the darker the brightness of the load light source 70. The conduction of the switch module 40 is controlled by the second pulse signal. When the second pulse signal is at a high level, the switch module 40 is turned on under its action. When the second pulse signal is at a low level, the switch module 40 is turned off under its action.

[0054] When driving the load light source 70 to light up, the constant current control module 50 is used to receive the first pulse signal and the second pulse signal output by the controller 50, and receive the first sampling signal, and generate a switch drive signal according to the first pulse signal, the second pulse signal and the first sampling signal, and output it to the first controlled end 413 of the first switch of the switch module 40, triggering the first switch to turn on so that the load light source is powered and operates in a constant current state, or triggering the first switch to turn off so that the load light source loses power and goes out, thereby realizing constant current drive of the load light source 70.

[0055] In the above embodiment of the present disclosure, the load light source is powered by a power module. Without using an integrated driver chip, a constant current control module is formed by combining conventional electronic components. The constant current control module receives the first pulse signal and the second pulse signal sent by the controller, and controls the controlled end of the switch module in combination with the first sampling signal, that is, the amplitude and duty cycle of the drive signal and the sampling signal are combined to achieve constant current drive of the load light source. The brightness of the load light source can be determined according to the duty cycle of the second pulse signal, the operating current of the load light source can be determined according to the amplitude of the first pulse signal, and the voltage amplitude of the second pulse drive signal can be adaptively adjusted by the controller. It is backward compatible with load light sources of various operating currents to achieve constant current drive of load light sources with different rated powers, and has wide adaptability. At the same time, since the embodiment of the present disclosure uses conventional electronic components to combine various circuit modules instead of using an integrated driver chip, the production cost is low and easy to implement, which solves the production material problem caused by the lack of integrated chips.

[0056] The following describes various modules of the light source driving circuit in conjunction with the circuit diagram.

[0057] In an optional embodiment, if Figure 2 As shown, Figure 2This is a circuit schematic diagram of a constant current control module according to one embodiment of the present disclosure.

[0058] The first switch of the switch module 40 can be an N-channel field-effect transistor (FET) Q1, which has a gate G, a drain D, and a source S. When the N-channel FET forms a channel, the voltage between its gate G and source S is a turn-on voltage VT, i.e., a conduction voltage VT. The gate G of the N-channel FET Q1 can be the first controlled terminal 413 of the first switch, its drain D can be the first signal terminal 411 of the first switch, which also serves as a current input terminal, and its source S can be the second signal terminal 412 of the first switch, which also serves as a current output terminal. If the first signal terminal 411 of the first switch is connected to the cathode LED- of the load light source 70, the drain D of the N-channel FET Q1 is connected to the cathode of the load light source 70. If the second signal terminal 412 of the first switch is grounded through the current sampling module 60, the source S of the N-channel FET Q1 is connected to the reference ground through the current sampling module 60. The current sampling module 60 may be a sampling resistor R19 , and therefore, the source S of the N-channel field effect transistor Q1 is connected to the reference ground GND through the sampling resistor R19 .

[0059] If the voltage Vgs received by the gate G of the N-channel FET Q1 is greater than or equal to the turn-on voltage VT, the N-channel FET Q1 is turned on, and current flows from the drain D to the source S of the N-channel FET Q1. When the N-channel FET Q1 is turned on, a channel is formed in the N-channel FET Q1, and current flows between its drain D and source S, forming a load drive circuit, causing the load light source 70 to light up.

[0060] When the N-channel field effect transistor Q1 is turned on and operates in the variable resistance area, the voltage applied between the drain D and source S of the N-channel field effect transistor Q1 increases. At this time, the voltage across the load light source 70 decreases, and the driving current flowing through the load light source 70 decreases. When the N-channel field effect transistor Q1 is turned on and operates in the saturation area, the N-channel field effect transistor Q1 is equivalent to a small resistor connected in series in the circuit. At this time, the voltage across the load light source 70 increases, and the driving current flowing through the load light source 70 increases.

[0061] The operating state of the N-channel field effect transistor Q1 is determined by the magnitude of the switch drive signal, which is determined by the current signal of the sampling resistor R19. If the current flowing through the sampling resistor R19 is too small, the voltage between the gate G and source S of the N-channel field effect transistor Q1 will increase accordingly, that is, the voltage between the drain D and source S will decrease. If the voltage output of the power module 10 is constant, that is, the sum of the voltages between the load light source 70 and the drain D and source S of the N-channel field effect transistor Q1 is substantially constant, the voltage across the load light source 70 increases, and the drive current increases, thereby increasing the current flowing through the sampling resistor R19. Conversely, if the current flowing through the sampling resistor R19 is too large, the voltage between the gate G and source S of the N-channel field effect transistor Q1 will decrease accordingly, that is, the voltage between the drain D and source S will increase, the voltage across the load light source 70 will decrease, the drive current will decrease, and the current of the sampling resistor R19 will decrease, forming a negative feedback circuit, thereby achieving constant current drive of the load light source 70.

[0062] If the voltage Vgs received by the gate G of the N-channel field effect transistor Q1 is less than the turn-on voltage VT, the N-channel field effect transistor Q1 cannot form a channel and is in the cut-off state. At this time, no current flows from the drain D to the source S of the N-channel field effect transistor Q1, and a load driving circuit cannot be formed, and the load light source 70 is extinguished.

[0063] In other embodiments, the first switch of the switch module 40 may be a P-channel field effect transistor, an NPN transistor, a PNP transistor, or other switching elements, and the circuit connection method can be adaptively changed.

[0064] In this embodiment, the constant current control module 50 samples the operating current of the load light source 70, and then obtains the switch drive signal based on the current sampling signal and combined with the first pulse signal (ADIM) and the second pulse signal (PDIM) output by the controller 80 to adjust the working state of the switch module 40 to achieve constant current drive of the load light source 70.

[0065] The constant current control module 50 includes a first operational amplifier (U2A) and an amplitude adaptation circuit. The amplitude adaptation circuit has a reference voltage output terminal for outputting a reference voltage signal to a second signal input terminal of the first operational amplifier (U2A).

[0066] In this embodiment, Figure 2As shown, the switch module 40 is illustrated as an N-channel field effect transistor Q1. The drain D of the N-channel field effect transistor Q1 serves as the first signal terminal 411 of the switch module 40, i.e., the current input terminal. The source S of the N-channel field effect transistor Q1 serves as the second signal terminal 412 of the switch module 40, i.e., the current output terminal. The gate G of the N-channel field effect transistor Q1 serves as the first controlled terminal 413 of the switch module 40. When the voltage value of the switch drive signal received by the gate G of the N-channel field effect transistor Q1 is greater than the startup voltage VT of the N-channel field effect transistor Q1, the N-channel field effect transistor Q1 is turned on, thereby triggering the light source load 70 connected to the load drive circuit to illuminate.

[0067] In this embodiment, the current sampling module 60 is a sampling resistor R19. The first end of the sampling resistor R19 is connected to the source S of the N-channel field-effect transistor Q1, and the second end is connected to the reference ground GND. When the N-channel field-effect transistor Q1 is turned on, current flows through the sampling resistor R19. The current flowing through the sampling resistor R19 is consistent in magnitude and direction with the current flowing through the load light source 70. Therefore, by sampling the current at the first end of the sampling resistor R19, the operating current of the load light source 70 can be sampled. Optionally, the end of the sampling resistor R19 connected to the N-channel field-effect transistor Q1 serves as a first sampling node.

[0068] In other embodiments, other nodes in the load driving loop may be selected as current sampling nodes. The current sampling module may be other components.

[0069] The first operational amplifier (U2A) includes a first signal input terminal (the inverting input terminal of U2A, i.e., pin 2), a second signal input terminal (the non-inverting input terminal of U2A, i.e., pin 3), and a first signal output terminal (pin 1 of U2A). The first signal input terminal (the inverting input terminal of U2A, i.e., pin 2) is connected to the first sampling node, the second signal input terminal (the non-inverting input terminal of U2A, i.e., pin 3) is connected to the reference voltage output terminal (PWM_REF1) of the amplitude adaptation circuit, and the first signal output terminal (pin 1 of U2A) is connected to the first controlled terminal 413 of the switch module 40. In other words, the first signal output terminal (pin 1 of U2A) is connected to the gate G of the N-channel field-effect transistor Q1. Optionally, the first signal output terminal (pin 1 of U2A) is connected to the gate G of the N-channel field-effect transistor Q1 through a current-limiting resistor R22.

[0070] The first operational amplifier (U2A) is used to compare the first sampling signal with the reference voltage signal (PWM_REF1), the first signal input end is the inverting input end of the first operational amplifier (U2A), and the second signal input end is the non-inverting input end of the first operational amplifier (U2A).

[0071] The working principle of the first operational amplifier is: if the voltage value of the inverting input terminal is greater than the voltage value of the non-inverting input terminal, the voltage value of the switch drive signal output by its first signal output terminal decreases; if the voltage value of the non-inverting input terminal is greater than the voltage value of the inverting input terminal, the voltage value of the switch drive signal output by its first signal output terminal increases.

[0072] If the voltage value of the reference voltage signal at the second signal input terminal is greater than the voltage value of the first sampling signal at the first signal input terminal, the first operational amplifier outputs a high-level signal to drive the first switch to be turned on and operate in the first state or the second state, so that the operating current of the load light source decreases or increases, and the constant current drive lightens the load light source;

[0073] If the voltage value of the reference voltage signal at the second signal input terminal is less than the voltage value of the first sampling signal at the first signal input terminal, the first operational amplifier outputs a low-level signal to the first switch to turn it off, thereby powering off the load light source.

[0074] Specifically, if the voltage value of the reference voltage signal at the second signal input terminal is greater than the voltage value of the first sampling signal at the first signal input terminal, the first operational amplifier (U2A) outputs a high-level signal with a higher voltage value to the gate G of the N-channel field-effect transistor Q1 of the switch module 40. That is, if the voltage value of the high-level signal is greater than the startup voltage VT of the N-channel field-effect transistor Q1, the N-channel field-effect transistor Q1 can be driven to turn on. When the N-channel field-effect transistor Q1 is turned on and operates in the variable resistance region, a voltage Vds exists between the drain D and source S of the N-channel field-effect transistor Q1. At this time, the voltage across the load light source 70 decreases, and the drive current flowing through the load light source 70 decreases. This will cause the current flowing through the sampling resistor R19 to decrease, making the voltage value of the first sampling signal at the first signal input terminal smaller, forming negative feedback. The first operational amplifier (U2A) then determines the switch drive signal at its output terminal based on the voltage difference between the two input terminals, and adjusts the working state of the N-channel field effect transistor Q1 through the switch drive signal, thereby causing the operating current of the load light source 70 to fluctuate within the set range.

[0075] When Vds of the N-channel field effect transistor Q1 is greater than Vgs-VT (Vds is the voltage difference between the drain and source of the N-channel field effect transistor Q1, and Vgs is the voltage difference between the gate and source of the N-channel field effect transistor Q1), the N-channel field effect transistor Q1 operates in the saturation region, that is, the N-channel field effect transistor Q1 is fully turned on. At this time, the N-channel field effect transistor Q1 is equivalent to a small resistor connected in series in the circuit. The voltage drop of the N-channel field effect transistor Q1 is approximately 0.3V, the voltage across the two ends of the load light source 70 increases, and the driving current flowing through the load light source 70 increases.

[0076] As described above, by regulating the switch drive signal through the first operational amplifier U2A, the conduction state of the N-channel field effect transistor Q1 can be regulated, and then the voltage at both ends of the load light source 70 can be regulated. The voltage at both ends of the load light source 70 can determine the current flowing through the load light source 70, thereby realizing constant current drive.

[0077] If the reference voltage signal of the second signal input terminal is pulled low, its voltage value is less than the voltage value of the first sampling signal of the first comparison signal input terminal, then the first signal output terminal outputs a low-level signal to the N-channel field effect transistor Q1 of the switch module 40, which cannot drive it to turn on, and the N-channel field effect transistor Q1 is cut off.

[0078] In an optional embodiment, an RC loop compensation circuit is further provided between the first signal output terminal and the first signal input terminal of the first operational amplifier (U2A). The RC loop compensation circuit includes a matching capacitor C12 and a matching resistor R13. The matching capacitor C12 and the matching resistor R13 are connected in series with each other, and the matching resistor R13 is connected to the first signal output terminal of the first operational amplifier (U2A). The matching capacitor C12 is connected to the first signal input terminal of the first operational amplifier (U2A), forming feedback, so that the input voltage can be amplified and output. In a closed-loop system, a loop compensation circuit is added to the feedback to compensate for the insufficient performance of the comparator (U2A) during disturbances, thereby maintaining a stable or optimal state of the voltage comparator.

[0079] like Figure 3 As shown, Figure 3 Schematic diagram of the connection of the amplitude adaptation circuit of the embodiment of the present disclosure.

[0080] The amplitude adaptation circuit has a first pulse signal input terminal, which is the first drive input terminal 502 of the constant current control module 50. The first pulse signal input terminal is used to connect to the first pulse signal output terminal 801 of the controller 80. The amplitude adaptation circuit receives the first pulse signal ADIM, adjusts the first pulse signal ADIM, and outputs a reference voltage signal with a constant amplitude at its reference voltage output terminal to the second signal input terminal (in-phase input terminal) of the first operational amplifier U2A.

[0081] The amplitude adaptation circuit has a second pulse signal input terminal, which is the second drive input terminal 503 of the constant current control module 50 and is used to connect to the second pulse signal output terminal 802 of the controller 80. The amplitude adaptation circuit receives the second pulse signal PDIM and pulls down the first pulse signal ADIM through the second pulse signal PDIM, so that a low voltage signal can be output to the second signal input terminal (non-inverting input terminal) of the first operational amplifier, thereby controlling the first switch to be turned off.

[0082] The amplitude adaptation circuit receives the first pulse signal (ADIM) and the second pulse signal (PDIM) output by the controller 80. When the second pulse signal (PDIM) is at a high level, the reference voltage output end of the amplitude adaptation circuit outputs a reference voltage signal corresponding to the preset amplitude of the first pulse signal (ADIM) to the second signal input end of the first operational amplifier U2A; when the second pulse signal (PDIM) is at a low level, the amplitude adaptation circuit lowers the level of the first pulse signal (ADIM) to obtain a low-level reference voltage signal, and outputs it to the second signal input end of the first operational amplifier U2A, so as to facilitate the regulation of the output voltage of the first signal output end of the first operational amplifier U2A, thereby realizing the regulation of the switch drive signal.

[0083] In order to control the voltage level of the second signal input terminal (non-inverting input terminal) (pin 3 of U2A) of the first operational amplifier (U2A), a reference voltage control circuit 511 is provided in the constant current control module.

[0084] The amplitude adaptation circuit includes a reference voltage control circuit 511, which includes a second switch Q4 and a third switch Q5 electrically connected to each other. The second switch Q4 has a third signal terminal, a fourth signal terminal, and a second controlled terminal. The third signal terminal is connected to the first pulse signal input terminal (ADIM), and the fourth signal terminal is grounded. The third switch Q5 has a fifth signal terminal, a sixth signal terminal, and a third controlled terminal. The fifth signal terminal is connected to the second controlled terminal of the second switch Q4 and then to a +5V auxiliary power supply. The sixth signal terminal is grounded, and the third controlled terminal is connected to the second pulse signal input terminal (PDIM) for connection to the second pulse signal output terminal 802 of the controller 80. The reference voltage control circuit 511 is used to determine whether to pull the reference voltage signal (PWM_REF1) low. The first operational amplifier U2A determines the signal level outputted by its first signal output terminal based on the input signals at its two input terminals. By regulating the reference voltage signal, the output voltage of the first signal output terminal of the first operational amplifier U2A can be regulated, thereby regulating the switch drive signal.

[0085] The principle of the reference voltage control circuit is described below.

[0086] Optionally, the second switch Q4 may be a transistor, a field effect transistor, or other switching devices.

[0087] Optionally, the third switch Q5 may be a transistor, a field effect transistor, or other switching devices.

[0088] In this embodiment, the second switch Q4 can be an N-channel field effect transistor Q4, and the third switch Q5 can be an N-type transistor Q5.

[0089] When the second switch Q4 is an N-channel field effect transistor Q4, the drain D of the N-channel field effect transistor Q4 is the third signal end, i.e., the current input end, the source S of the N-channel field effect transistor Q4 is the fourth signal end, i.e., the current output end, and the gate G of the N-channel field effect transistor Q4 is the second controlled end. When the second controlled end of the N-channel field effect transistor Q4 is connected to the +5V auxiliary power supply to obtain a trigger voltage, the N-channel field effect transistor Q4 is turned on, and the current input end and the current output end of the N-channel field effect transistor Q4 are turned on, so as to pull down the reference voltage signal (PWM_REF1) of the reference voltage output end to the ground, thereby transmitting a low-level signal to the second signal input end (the in-phase input end) of the first operational amplifier (U2A). When the second signal input end (the in-phase input end) of the first operational amplifier (U2A) is at a low level, the first signal output end of the first operational amplifier (U2A) outputs a low-level signal, thereby controlling the N-channel field effect transistor Q1 to be turned off, and further turning off the load driving circuit in which the load light source 70 is located, and the load light source 70 is extinguished.

[0090] The third switch Q5 has a third controlled end, a fifth signal end, and a sixth signal end; the fifth signal end is connected to the second controlled end and then connected to the +5V auxiliary power supply, the sixth signal end is grounded, and the third controlled end is connected to the second pulse signal input end, for being connected to the second pulse signal output end of the controller to receive the second pulse signal, and the second pulse signal is a PWM pulse modulation signal PDIM.

[0091] When the third switch Q5 is an NPN transistor Q5, the collector C of the NPN transistor Q5 is the current input end, which is connected to the +5V auxiliary power supply after being connected to the gate G of the N-channel field effect transistor Q4; the emitter E of the NPN transistor Q5 is the current output end, which is grounded, and the base B of the NPN transistor Q5 is connected to the second pulse signal input end through the resistor R16 to obtain the second pulse signal PDIM. When the gate G of the NPN transistor Q5 receives a high-level signal, the NPN transistor Q5 is turned on, the voltage of the gate G of the N-channel field effect transistor Q4 is pulled down, so that the voltage of the gate of the N-channel field effect transistor Q4 cannot reach its internal conduction voltage, and the N-channel field effect transistor Q4 is turned off, which does not affect the voltage value of the reference voltage signal (PWM_REF1) output by the reference voltage output end of the amplitude adaptation circuit.

[0092] If the voltage value of the reference voltage signal (PWM_REF1) input to the non-inverting input terminal of the first operational amplifier (U2A) is greater than the voltage value of the first sampling signal, the first signal output terminal of the first operational amplifier (U2A) outputs a high-level signal, triggering the N-channel field effect transistor Q1 of the switch module to turn on.

[0093] If the operating current in the load drive circuit is high, the current at the first sampling node is high, and the voltage converted and transmitted to the first signal input terminal of the first operational amplifier (U2A) is high. During the same operating time of the load light source, the amplitude of the reference voltage signal does not change. At this time, the voltage value at the first signal input terminal is high, the voltage difference between the reference voltage signal and the first sampling signal decreases, and the high-level signal at the first signal output terminal decreases, causing N-channel field-effect transistor Q1 to conduct and operate in the variable resistance region, thereby reducing the voltage across the load light source 70 and the drive current flowing through the load light source 70.

[0094] As the drain voltage of the N-channel field effect transistor Q1 continues to increase, the N-channel field effect transistor Q1 can operate in the saturation region. At this time, the voltage drop between the drain D and the source S of the N-channel field effect transistor Q1 is very small, so the voltage across the two ends of the load light source 70 becomes larger, and the driving current flowing through the load light source 70 becomes larger. Through continuous adjustment, the load light source 70 can eventually achieve constant current drive.

[0095] When the gate G of the NPN transistor Q5 receives a low-level signal, the NPN transistor Q5 is turned off, so that the gate G of the N-channel field-effect transistor Q4 is connected to the +5V auxiliary power supply, so that the voltage of the gate G of the N-channel field-effect transistor Q4 reaches its starting voltage VT, triggering the N-channel field-effect transistor Q4 to be turned on, and the drain D of the N-channel field-effect transistor Q4 is grounded through the source S, thereby pulling down the reference voltage signal output from the reference voltage output end of the amplitude adaptation circuit, and the reference voltage signal (PWM_REF1) input to the non-inverting input end of the first operational amplifier (U2A) is pulled low, and the first signal output end of the first operational amplifier (U2A) outputs a low-level signal, triggering the N-channel field-effect transistor Q1 of the switch module to be turned off, triggering the load light source to lose power and extinguish.

[0096] Optionally, a voltage divider circuit is further provided at the third controlled terminal of the third switch Q5, comprising resistors R16 and R29. Resistors R16 and R29 form a voltage divider circuit that divides the voltage of the second pulse signal and transmits it to the third controlled terminal of the third switch Q5, thereby preventing damage to the third switch Q5 caused by excessive voltage of the second pulse signal.

[0097] In an optional embodiment, the amplitude adaptation circuit further includes a voltage stabilizing circuit 512 , and the voltage stabilizing circuit 512 includes a first controllable precision voltage stabilizing device U4 and a first voltage stabilizing matching resistor R44 .

[0098] The first controllable precision voltage regulator U4 has an anode A, a cathode K, and a reference electrode R. The anode A of the first controllable precision voltage regulator U4 is grounded, and its cathode K is connected to the first pulse signal input terminal via the first voltage-stabilizing matching resistor R44 to obtain the first pulse signal ADIM. The reference electrode R and cathode K are connected to form a first voltage-stabilized output terminal, which is connected to the second signal input terminal of the first operational amplifier U2A, that is, to the non-inverting input terminal of the first operational amplifier U2A, to transmit the reference voltage signal to the first operational amplifier U2A. The first controllable precision voltage regulator U4 can be a TL431 or TL432, and its model can be determined according to circuit requirements.

[0099] If the amplitude of the first pulse signal ADIM received by the first pulse signal input terminal is 1.25V, and if the reference voltage of the first controllable precision voltage stabilizer U4 is 1.25V, the first controllable precision voltage stabilizer U4 can stabilize the first pulse signal at 1.25V, thereby outputting a reference voltage signal with constant amplitude.

[0100] If the amplitude of the first pulse signal received by the first pulse signal input terminal is 2.5V, and if the reference voltage of the first controllable precision voltage stabilizer U4 is 2.5V, the first controllable precision voltage stabilizer U4 can stabilize the first pulse signal at 2.5V, thereby outputting a reference voltage signal with a constant amplitude.

[0101] During the same driving period, the controller 80 outputs a first pulse signal ADIM with a constant amplitude. The voltage stabilizing circuit 512 is used to further stabilize the first pulse signal ADIM to obtain a reference voltage signal, which is transmitted to the second signal input terminal of the first operational amplifier U2A to obtain a more stable reference voltage signal, thereby improving the accuracy of regulating the switch module 40.

[0102] Optionally, the voltage stabilization circuit 512 further includes a first voltage-dividing resistor R54, a second voltage-dividing resistor R57, a first filter resistor R56, and a first filter capacitor C37. The first end of the first voltage-dividing resistor R54 is connected to the first voltage-stabilized output terminal, and the second end of the first voltage-dividing resistor R54 is connected to the first end of the second voltage-dividing resistor R57. The connection between the first voltage-dividing resistor R54 and the second voltage-dividing resistor R57 forms the reference voltage output terminal (PWM_REF1) of the amplitude adaptation circuit, and the second end of the second voltage-dividing resistor R57 is grounded. The first filter resistor R56 is connected in parallel with the second voltage-dividing resistor R57. The first filter capacitor C37 is connected in parallel with the second voltage-dividing resistor R57 to filter the reference voltage signal.

[0103] The first pulse signal ADIM is stabilized by the first controllable precision voltage regulator U4 and then forms a reference voltage signal with the output terminal. This reference voltage signal is filtered to form a reference voltage signal PWM_REF1 with low noise and stable amplitude, which is input to the non-inverting input terminal (pin 3 of U2A) of the first operational amplifier (U2A). In an optional embodiment, the inverting input terminal (pin 2 of U2A) of the first operational amplifier U2A can be connected to the first sampling node via a conversion resistor R25. After the sampling current of the first sampling node passes through the conversion resistor R25, a corresponding voltage sampling signal can be obtained.

[0104] Or, in an alternative embodiment, as Figure 2 As shown, the first signal input terminal (inverting input terminal) of the first operational amplifier (U2A) can be connected to the first sampling node through the current detection circuit 513.

[0105] The current detection circuit 513 includes a second operational amplifier U2B, a first conversion resistor R21 and a first feedback resistor R11; the second operational amplifier U2B includes a third signal input terminal, a fourth signal input terminal and a second signal output terminal, the third signal input terminal is an inverting input terminal (the inverting input terminal of U2B, that is, the 6th pin of U2B), the third signal input terminal is grounded, the fourth signal input terminal is a non-inverting input terminal (the non-inverting input terminal of U2B, that is, the 5th pin of U2B), the fourth signal input terminal is connected to the first sampling node through the first conversion resistor R21, and the second signal output terminal is connected to the first signal input terminal of the first operational amplifier U2A; the first feedback resistor R11 is connected between the second signal output terminal and the third signal input terminal.

[0106] The current detection circuit 513 is used to convert the sampled current from the first sampling node into a voltage signal and output it to the inverting input terminal of the first operational amplifier U2A (pin 2 of U2A) after amplification. Adding the current detection circuit 513 can improve the sensitivity of current sampling and obtain a better constant current driving effect.

[0107] Specifically, the sampling current obtained at the first sampling node is converted into a corresponding voltage signal after passing through the conversion resistor R21 and input into the non-inverting input terminal of the second operational amplifier (U2B). Since the inverting input terminal of the second operational amplifier (U2B) is grounded, the voltage value of the non-inverting input terminal is greater than the voltage value of the inverting input terminal. The second signal output terminal outputs the amplified voltage sampling signal, and the voltage sampling signal is transmitted to the first comparison signal input terminal of the first operational amplifier (U2A) through the current limiting resistor R18 to improve the sensitivity of current sampling and obtain a better constant current driving effect.

[0108] If the voltage across the load light source 70 decreases, the driving current flowing through the load light source 70 decreases, which will cause the current flowing through the detection resistor R19 to decrease, making the signal after passing through the signal amplification circuit composed of the second operational amplifier U2B smaller, and the voltage value transmitted to the first signal input terminal smaller, thereby forming a negative feedback, and ultimately causing the operating current of the load light source to fluctuate within the set range.

[0109] Based on the above embodiment's ability to achieve constant current driving of the load light source, to achieve a constant voltage function in the light source driver circuit, the light source driver circuit further includes a constant voltage control module, and the power module includes a voltage sampling terminal. The connection between the second load connection terminal 30 and the first signal terminal 401 of the switch module 40 forms a second sampling node.

[0110] like Figure 4 As shown, Figure 4 4 is a principle block diagram of a constant voltage control module according to an embodiment of the present disclosure.

[0111] The constant voltage control module has a second sampling terminal 901, a third drive input terminal 902 and a voltage feedback output terminal 903. The second sampling terminal 901 is connected to the second sampling node and is used to receive the second sampling signal of the load drive circuit. Its third drive input terminal 902 is used to be connected to the first pulse signal output terminal of the controller 80 to receive the first pulse signal ADIM. Its voltage feedback output terminal 903 is connected to the voltage sampling terminal FB of the power supply module 10.

[0112] The constant voltage control module is configured to receive the second sampling signal and the first pulse signal ADIM output by the controller 80, and generate a voltage feedback signal based on the second sampling signal and the first pulse signal ADIM, and output the signal to the voltage sampling terminal FB of the power module 10. The power module 10 receives the voltage feedback signal and outputs a corresponding power drive signal to the first load connection terminal 20. The power drive signal is configured to provide driving power for the load light source 70.

[0113] The constant voltage control module includes a first voltage comparator (U3A), which includes a fifth signal input terminal (pin 3 of U3A), a sixth signal input terminal (pin 2 of U3A) and a third signal output terminal (pin 1 of U3A).

[0114] The fifth signal input terminal is connected to the second sampling terminal to receive the second sampling signal, the sixth signal input terminal is the third drive input terminal, which is used to be connected to the first pulse signal output terminal of the controller 80, and the third signal output terminal is the voltage feedback output terminal, which is used to be connected to the voltage sampling terminal FB of the power supply module 10.

[0115] Among them, if the sixth signal input terminal is directly connected to the first pulse signal output terminal of the controller 80, a first pulse signal ADIM can be obtained. The first pulse signal ADIM serves as a preset reference voltage signal of the first voltage comparator, and the voltage value of the first pulse signal ADIM can be a preset reference voltage value.

[0116] If the voltage value of the fifth signal input terminal is less than the preset reference voltage value of the sixth signal input terminal, the third signal output terminal outputs a high-level voltage feedback signal to the voltage sampling terminal FB of the power module 10; if the voltage value of the fifth signal input terminal is greater than the preset reference voltage value of the sixth signal input terminal, the third signal output terminal outputs a low-level voltage feedback signal to the voltage sampling terminal FB of the power module 10; the power module 10 receives the high-level voltage feedback signal and outputs a power drive signal of a first preset voltage value to the first load connection terminal 20; when the power module 10 receives the low-level voltage feedback signal, it outputs a power drive signal of a second preset voltage value to the first load connection terminal 20, thereby achieving constant voltage regulation, so that the voltage output by the output terminal of the power module 10 remains constant, thereby preventing the LED light source load from being damaged due to excessive voltage. The first preset voltage value and the second preset voltage value can be determined by the inventor based on business experience, and the specific voltage values ​​are not limited in this embodiment.

[0117] In an optional embodiment, the constant voltage control module includes a voltage follower circuit 91, which includes a first diode D2, a first resistor R46, a second resistor R47, and a third resistor R45. The cathode of the first diode D2 is the second sampling terminal, the cathode of the first diode D2 is connected to the second sampling node, the anode of the first diode D2 is connected to the fifth signal input terminal (pin 3 of U3A) through the first resistor R46 and the second resistor R47, and the connection end of the first resistor R46 and the second resistor R47 is connected to the bias voltage source through the third resistor R45. The voltage of the bias voltage source is determined according to the circuit requirements.

[0118] If the bias voltage source is 2.5V, when the first switch Q1 is turned on, the drain D of the first switch Q1 is connected to ground through the source S, that is, LED- is grounded. The third resistor R45 and the first resistor R46 divide the 2.5V voltage and input it to the fifth signal input terminal (pin 3 of U3A) through the second resistor R47. This is equivalent to a voltage lower than 2.5V input to the fifth signal input terminal (pin 3 of U3A) and lower than the reference voltage set by the sixth signal input terminal (pin 2 of U3A). The first voltage comparator (U3A) outputs a low-level signal. At this time, the voltage sampling terminal FB of the power supply module 10 receives a low-level signal and accordingly increases the voltage output to achieve constant voltage drive.

[0119] When the first switch Q1 is turned off, the drain D of the first switch is at a high level, LED- is at a high level, and the first diode D2 isolates the high level of LED-, thereby preventing the voltage in the drive circuit from affecting the constant voltage control module. At this time, the voltage value input by the fifth signal input terminal (pin 3 of U3A) is the voltage value introduced by the +2.5V bias voltage source, and the voltage value input by the fifth signal input terminal (pin 3 of U3A) is greater than the set reference voltage of the sixth signal input terminal (pin 2 of U3A), then the first voltage comparator (pin 1 of U3A) outputs a high level signal. At this time, the voltage sampling terminal FB of the power supply module 10 receives a high level signal, and the corresponding voltage output is reduced to achieve constant voltage drive, thereby achieving constant voltage drive of the load light source.

[0120] In an optional embodiment, if Figure 5 As shown, in order to provide a reference voltage signal to the fifth signal input terminal of the first voltage comparator (U3A), a reference voltage circuit 92 is required. The sixth signal input terminal of the first voltage comparator (U3A) is connected to a +2.5V bias voltage source through the reference voltage circuit 92.

[0121] The reference voltage circuit 92 includes a fourth resistor R53, a fifth resistor R48 and a sixth resistor R49; the sixth signal input terminal of the first voltage comparator (U3A) is connected to the bias voltage source through the sixth resistor R49 and the fifth resistor R48, the first end of the fourth resistor R53 is connected to the fifth resistor R48 and the sixth resistor R49, and the second end thereof is grounded; the fourth resistor R53 and the fifth resistor R48 form a voltage divider circuit, which divides the bias voltage source and transmits it to the sixth signal input terminal through the sixth resistor R49, providing a reference voltage signal for the first voltage comparator (U3A).

[0122] The second sampling signal and the reference voltage are transmitted to the input end of the first voltage comparator (U3A). The first voltage comparator (U3A) determines the signal at the output end according to the signal at the input end and transmits it to the power supply module so that the power supply module controls the voltage value at its output end to realize a constant voltage function.

[0123] In another optional embodiment, the sixth signal input terminal of the first voltage comparator is connected to the first pulse signal input terminal ADIM through the reference voltage circuit 92 .

[0124] Because the voltage across the detection resistor R19 is different under the regulation of different first pulse signals ADIM, in order to ensure that the light source driving circuit maintains a high efficiency under the regulation of different first pulse signals, the reference voltage circuit 92 also includes a second controllable precision voltage regulator U6, a second diode D12, and a seventh resistor R410; the anode A of the second controllable precision voltage regulator U6 is grounded, and its cathode K is connected to the sixth signal input terminal of the first voltage comparator (U3A) through the second diode D12 and the sixth resistor R49. Its reference electrode R is connected to the cathode K and then connected to the first pulse signal input terminal through the seventh resistor R410 to obtain the first pulse signal. Using the magnitude of the first pulse signal as a reference voltage source can effectively achieve constant voltage drive.

[0125] The reference voltage circuit is set up to stabilize the amplitude of the first pulse signal ADIM at 2.5V through the second controllable precision voltage regulator U6 to form a dimming waveform with a stable amplitude and unchanged duty cycle state, and to form an RC filter through the eighth resistor R411 and the filter capacitor C32. In this way, when the first pulse signal ADIM has a high duty cycle, a higher bias voltage is added to the reference voltage, making the reference voltage slightly higher, the current of the set load light source 70 larger, and the voltage of the detection resistor R19 slightly larger. When the first pulse signal ADIM has a low duty cycle, the bias amount is lower, making the reference voltage slightly lower, the current of the set load light source 70 smaller, and the voltage of the detection resistor R19 slightly smaller. In this way, the setting of the reference voltage can be proportional to the voltage of the detection resistor (the sampling voltage at the second sampling node), thereby achieving the purpose of correction and compensation.

[0126] Optionally, the second controllable precision voltage regulator U6 can be TL431, whose internal reference voltage is 2.5V, which can stabilize the third pulse signal (ADIM) at 2.5V, thereby providing a reference voltage signal for the sixth signal input terminal of the first voltage comparator (U3A).

[0127] The bias voltage source in the above embodiment can be obtained by stepping down the +5V voltage. Figure 6 As shown, the constant voltage control module also includes a bias voltage source module, which includes a current limiting resistor R50 and a third controllable precision voltage regulator U5. The anode A of the third controllable precision voltage regulator U5 is grounded, and its cathode K is connected to the +5V auxiliary power supply through the current limiting resistor R50. Its reference electrode R is connected to the cathode K to form a third voltage regulated output terminal, which can output a relatively stable +2.5V bias voltage source and input it to the sixth signal input terminal of the first voltage comparator (U3A) to provide a reference voltage signal. The provision of a bias voltage source in the constant voltage control module can improve the constant voltage driving performance of the load light source. The third controllable precision voltage regulator U5 can be TL321 or TL432.

[0128] In an optional embodiment, the constant voltage control module further includes a voltage buffer circuit 93 .

[0129] The voltage buffer circuit 93 includes a third diode D4, a fourth diode D3 and filter capacitors (C35 and C34); the cathode of the third diode D4 is connected to the third signal output terminal of the first voltage comparator (U3A), the anode of the third diode D4 is connected to the cathode of the fourth diode D3, the anode of the fourth diode D3 is connected to the voltage sampling terminal FB of the power module 10, and the connection between the third diode D4 and the fourth diode D3 is also grounded through the filter capacitors (C35 and C34).

[0130] When the voltage at the fifth signal input terminal of the first voltage comparator (U3A) is greater than the preset reference voltage value of the sixth signal input terminal, its third signal output terminal outputs a low-level signal, which can lower the feedback loop voltage through the third diode and the fourth diode, that is, lower the feedback voltage transmitted to the voltage sampling terminal of the power supply module, and the power supply module raises the output voltage to a certain value, so that the voltage difference between the two signal terminals of the switch module is stabilized at a relative value, which helps to achieve constant voltage drive.

[0131] In an optional embodiment, the constant voltage control module further includes a voltage feedback circuit.

[0132] See also Figure 7 , Figure 7 This is a circuit schematic diagram of a voltage feedback circuit according to an embodiment of the present disclosure.

[0133] The third signal output terminal of the first voltage comparator (U3A) is connected to the voltage sampling terminal FB of the power module 10 through the voltage feedback circuit.

[0134] The voltage feedback circuit includes a first feedback resistor R36, a second feedback resistor R37, a third feedback resistor R35, a fourth feedback resistor R40, a fifth feedback resistor R34, a sixth feedback resistor R30, a seventh feedback resistor R31 and a first feedback capacitor C27;

[0135] After the first end of the first feedback resistor R36 and the first end of the second feedback resistor R37 are connected, they are connected to the third signal output terminal of the first voltage comparator (U3A). After the second end of the first feedback resistor R36 and the second end of the second feedback resistor R37 are connected, they are grounded through the third feedback resistor R35 and the fourth feedback resistor R40, and are connected to the output terminal VOUT (voltage feedback) of the power module through the fifth feedback resistor R34 and the sixth feedback resistor R30. The end where the third feedback resistor R35 and the fourth feedback resistor R40 are connected is a voltage sampling node, which is connected to the voltage sampling terminal of the power module. The connection end of the first feedback resistor R36 and the second feedback resistor R37 is also connected to the output terminal VOUT of the power module through the first feedback capacitor C27 and the seventh feedback resistor R31.

[0136] If the third signal output terminal of the first voltage comparator (U3A) outputs a low-level signal, the signal at the voltage sampling node is pulled down to the ground, so the signal received by the power sampling terminal of the power module is a low-level signal, and then the power module can control to increase the voltage output to achieve constant voltage drive.

[0137] In this disclosure, please refer to Figure 8 , Figure 8A circuit schematic diagram of a power supply module shown for an embodiment of the present disclosure.

[0138] In an optional embodiment, the power supply module comprises a power input terminal VIN, a power output terminal VOUTA, a power management chip UB1, a fourth switch Q3, a fifth switch Q2 and an energy storage element LD1.

[0139] The power management chip UB1 is configured to control the controlled terminals of the fourth switch Q3 and the fifth switch Q2, so that the fourth switch Q3 and the fifth switch Q2 are correspondingly turned on or turned off, thereby outputting a power signal to the load light source.

[0140] The power management chip UB1 has an input terminal VIN, a first control signal output terminal HD and a second control signal output terminal LD; the input terminal VIN of the power management chip UB1 is connected to the power input terminal VIN to obtain a chip driving power supply. The power management chip UB1 further has an enable terminal EN1, which is connected to the power input terminal. Only when the enable terminal EN1 receives an electrical signal, the power management chip UB1 will start to work.

[0141] Optionally, the power management chip UB1 has a voltage sampling terminal FB, which is configured to be connected to a voltage feedback terminal of a voltage regulation module to obtain a voltage feedback signal, thereby facilitating the control of the fourth switch and the fifth switch to realize the regulation of the power output, such as constant voltage output regulation.

[0142] The fourth switch Q3 has a fourth controlled terminal, a seventh signal terminal and an eighth signal terminal.

[0143] The fifth switch Q2 has a fifth controlled terminal, a ninth signal terminal and a tenth signal terminal.

[0144] The seventh signal terminal of the fourth switch Q3 is connected to the power input terminal VIN, the eighth signal terminal of the fourth switch Q3 is connected to the ninth signal terminal of the fifth switch Q2, and the tenth signal terminal of the fifth switch Q2 is grounded; the fourth controlled terminal of the fourth switch Q3 is connected to the first control signal output terminal HD, and the fifth controlled terminal of the fifth switch Q2 is connected to the second control signal output terminal LD. The first end of the energy storage element LD1 is connected to the eighth signal terminal of the fourth switch Q3 and the ninth signal terminal of the fifth switch Q2, and the second end of the energy storage element LD1 is the first load connection terminal, which is configured to be connected to the load light source.

[0145] The fourth switch Q3 and the fifth switch Q2 can be triodes, field effect transistors or other switching devices, which are not limited in the embodiment and the specific models are also not limited.

[0146] Optionally, the fourth switch Q3 may be an N-channel field-effect transistor Q3 having a gate, a source, and a drain. The gate of the N-channel field-effect transistor Q3 serves as the fourth controlled terminal of the fourth switch Q3 and is connected to the first control signal output terminal of the power management chip UB1. The drain serves as the seventh signal terminal of the fourth switch Q3 and is connected to the power input terminal VIN. The source is connected to the drain of the fifth switch Q2 via a current-limiting resistor. If the fourth switch Q3 is another switching element, the connection method can be adapted accordingly.

[0147] Optionally, the fifth switch Q2 may be an N-channel field-effect transistor Q2 having a gate, a source, and a drain. The gate of the N-channel field-effect transistor Q2 serves as the fifth controlled terminal of the fifth switch Q2 and is connected to the second control signal output terminal of the power management chip UB1. The drain serves as the ninth signal terminal of the fifth switch Q2 and is used to connect to the source of the fourth switch Q3. The source is grounded and connected to the output terminal of the switch module 40. If the fifth switch Q2 is another switching element, the connection method can be adapted accordingly.

[0148] Optionally, the energy storage element LD1 can be an energy storage capacitor, an energy storage inductor, a rechargeable battery, or other energy storage elements, which are not limited in this embodiment. In order to reduce output noise when the energy storage element releases energy, filter capacitors (ED3, C13 and C8) are also provided at both ends of the energy storage element LD1.

[0149] When the power management chip outputs a high-level signal to the fourth controlled terminal of the fourth switch, and the voltage value of the high-level signal is greater than the internal start-up voltage of the fourth switch, the fourth switch Q3 is turned on, so that the drain of the fifth switch Q2 and the first end of the energy storage element are connected to the power input terminal to obtain power.

[0150] If the power management chip outputs a low-level signal to the fifth controlled end of the fifth switch, the low-level signal cannot reach the internal starting voltage of the fifth switch, so the fifth switch is turned off. At this time, the first end of the energy storage element is connected to the power input end to obtain power for charging and energy storage, and provides driving power for the load light source connected to the back end.

[0151] When the power management chip outputs a low-level signal to the fourth controlled end of the fourth switch, and the voltage value of the low-level signal is less than the internal starting voltage of the fourth switch, the fourth switch Q3 is turned off, so that the drain of the fifth switch Q2 and the first end of the energy storage element cannot be connected to the power input end.

[0152] If the power management chip outputs a high level signal to the fifth control end of the fifth switch Q2, the voltage value of the high level signal is greater than the internal starting voltage of the fifth switch Q2, so the fifth switch Q2 is turned on, at this time the energy storage element, the first load connection end, the load light source, the second load connection end, the switch module and the fifth switch form a discharge circuit, and the load light source is continuously powered to make the load light source continuously light up.

[0153] The voltage sampling end FB of the power management chip is used for connecting the voltage feedback end INV1 of the voltage regulation module, so as to obtain the voltage feedback signal, and facilitate control of the voltage output of the power output end.

[0154] When the switch module is turned on and the load light source is lighted, the second load connection end LED- is grounded, at this time the second load connection end LED- is low level, and the voltage regulation module feeds back the low level signal to the voltage sampling end FB of the power management chip. When the voltage feedback signal received by the voltage sampling end FB of the power management chip is low level, the first control signal end of the power management chip continuously outputs a high level signal to drive the fourth switch to be turned on, and the on-off frequency of the fourth switch can be adjusted to increase the voltage output by the power output end, so as to realize constant voltage output.

[0155] When the switch module is turned off and the load light source is extinguished, the second load connection end LED- is high level, and the voltage regulation module feeds back the high level signal to the voltage sampling end FB of the power management chip. When the voltage feedback signal received by the voltage sampling end FB of the power management chip is high level, the first control signal end of the power management chip outputs a low level signal to drive the fourth switch to be turned off, and the on-off frequency of the fourth switch can be adjusted to decrease the voltage output by the power output end, so as to realize constant voltage output.

[0156] In other embodiments, the power module 1 also adopts other circuit connection structures, which are not limited in the embodiments of the present disclosure.

[0157] It should be noted that the first pulse signal and the second pulse signal can be pulse modulation signals with the same or different amplitudes and the same or different duty cycles, and the form of each pulse signal can be determined according to actual needs.

[0158] In the above embodiment of the present disclosure, the load light source is powered by a power supply module. Without using an integrated driver chip, a constant current control module is formed by combining conventional electronic components. The constant current control module receives the first pulse signal and the second pulse signal sent by the controller, and controls the controlled end of the switch module in combination with the first sampling signal, that is, the amplitude and duty cycle of the drive signal and the sampling signal are combined to achieve constant current drive of the load light source. The brightness of the load light source can be determined according to the duty cycle of the pulse signal, and the operating current of the load light source can be determined according to the amplitude of the pulse signal. The amplitude of the pulse drive signal can be adaptively adjusted by the controller, and it is backward compatible with load light sources of various operating currents to achieve constant current drive of load light sources with different rated powers, and has wide adaptability.

[0159] Furthermore, without using an integrated driver chip, conventional electronic components are combined into various functional modules, and pulse modulation signals and sampling signals are combined to achieve constant current and constant voltage driving of the load light source, which reduces the difficulty of implementing the load driving circuit and reduces production costs.

[0160] The present disclosure provides a light source device, such as Figure 1 As shown, the device comprises a controller, an LED light source, and a light source driving circuit as described in any of the above embodiments. The LED light source is connected in series to a load driving circuit of the light source driving circuit. The controller is configured to output a pulse signal to the light source driving circuit to control the LED light source to illuminate, operate in a constant current state, or extinguish.

[0161] In the light source device, the load light source is powered by the power supply module, the first pulse signal and the second pulse signal sent by the controller are received by the constant current control module, and the controlled end of the switch module is controlled in combination with the current sampling signal, that is, the amplitude and duty cycle of the driving signal and the sampling signal are combined to achieve constant current drive of the load light source; at the same time, the first pulse signal sent by the controller is received by the constant voltage control module, and the first pulse signal and the voltage sampling signal are combined to obtain a voltage feedback signal and feed it back to the power supply module, so that the power supply module can adjust the voltage output to achieve constant voltage drive.

[0162] The technical solution of the embodiment of the present disclosure, without using an integrated driver chip, combines conventional electronic components into various functional modules, combines the duty cycle and amplitude of the pulse signal, and combines the sampling signal to achieve constant current and constant voltage driving of the load light source, thereby reducing the difficulty of implementing the load driving circuit and reducing production costs.

[0163] The present disclosure is not limited to the above-mentioned embodiments. If various changes or modifications to the present disclosure do not depart from the spirit and scope of the present disclosure, and if these changes and modifications fall within the scope of the claims and equivalent technologies of the present disclosure, the present disclosure is also intended to include these changes and modifications.

Claims

1. A light source driving circuit, characterized in that: include: A power supply module, a first load connection terminal, a second load connection terminal, a switch module, a constant current control module and a current sampling module; The first load connection end is used to connect to a first end of a load light source, and the second load connection end is used to connect to a second end of the load light source; The switch module includes a first switch having a first signal terminal, a second signal terminal and a first controlled terminal; When a load light source is connected between the first load connection terminal and the second load connection terminal, the output terminal of the power module, the first load connection terminal, the second load connection terminal, the first signal terminal of the switch module, the second signal terminal of the switch module, and the ground terminal of the power module are connected in sequence to form a load driving loop; The current sampling module is connected in series in the load driving circuit, and the connection between the current sampling module and the first switch forms a first sampling node; The constant current control module has a first sampling terminal, a first driving input terminal, a second driving input terminal and a current regulating terminal. The first sampling terminal of the constant current control module is connected to the first sampling node and is used to receive a first sampling signal. The first driving input terminal is used to be connected to the first pulse signal output terminal of the controller, and the second driving input terminal is used to be connected to the second pulse signal output terminal of the controller. The current regulating terminal is connected to the first controlled terminal of the switch module; The constant current control module is used to receive the first pulse signal and the second pulse signal output by the controller, and receive the first sampling signal, and generate a switch drive signal according to the first pulse signal, the second pulse signal and the first sampling signal, and output it to the first controlled end of the first switch of the switch module, triggering the first switch to turn on so that the load light source is powered and operates in a constant current state, or triggering the first switch to turn off so that the load light source loses power and extinguishes.

2. The light source driving circuit according to claim 1, wherein: The constant current control module includes a first operational amplifier and an amplitude adaptation circuit; the amplitude adaptation circuit has a reference voltage output terminal; The first operational amplifier includes a first signal input terminal, a second signal input terminal, and a first signal output terminal, the first signal input terminal being connected to the first sampling node to obtain a first sampling signal, the second signal input terminal being connected to the reference voltage output terminal of the amplitude adaptation circuit to obtain a reference voltage signal, and the first signal output terminal being connected to the first controlled terminal of the first switch to output the switch driving signal to the first switch; If the voltage value of the reference voltage signal at the second signal input terminal is greater than the voltage value of the first sampling signal at the first signal input terminal, the first operational amplifier outputs a high-level signal to drive the first switch to be turned on and operate in the first state or the second state, so that the operating current of the load light source decreases or increases, and the constant current drive lightens the load light source; If the voltage value of the reference voltage signal at the second signal input terminal is less than the voltage value of the first sampling signal at the first signal input terminal, the first operational amplifier outputs a low-level signal to the first switch to turn it off, thereby powering off the load light source.

3. The light source driving circuit according to claim 2, wherein: The amplitude adaptation circuit has a first pulse signal input terminal and a second pulse signal input terminal; The first pulse signal input terminal is the first driving input terminal of the constant current control module, and the first pulse signal input terminal is used to connect to the first pulse signal output terminal of the controller to receive the first pulse signal; The second pulse signal input terminal is the second driving input terminal of the constant current control module, and the second pulse signal input terminal is used to be connected to the second pulse signal output terminal of the controller to receive the second pulse signal; The amplitude adaptation circuit receives the first pulse signal and the second pulse signal output by the controller, When the second pulse signal is at a high level, the reference voltage output terminal of the amplitude adaptation circuit outputs a reference voltage signal corresponding to the preset amplitude of the first pulse signal to the second signal input terminal of the first operational amplifier; When the second pulse signal is at a low level, the amplitude adaptation circuit lowers the level of the first pulse signal to obtain a low-level reference voltage signal, and outputs the signal to the second signal input terminal of the first operational amplifier.

4. The light source driving circuit according to claim 3, wherein: The amplitude adaptation circuit includes a reference voltage control circuit; The reference voltage control circuit includes a second switch and a third switch electrically connected to each other; The second switch has a third signal terminal, a fourth signal terminal and a second controlled terminal, the third signal terminal is connected to the first pulse signal input terminal, and the fourth signal terminal is grounded. The third switch has a fifth signal terminal, a sixth signal terminal and a third controlled terminal; the fifth signal terminal is connected to the second controlled terminal of the second switch and then connected to the auxiliary power supply, the sixth signal terminal is grounded, and the third controlled terminal is connected to the second pulse signal input terminal, which is used to be connected to the second pulse signal output terminal of the controller.

5. The light source driving circuit according to claim 3, wherein: The amplitude adaptation circuit further includes a voltage stabilizing circuit, which includes a first controllable precision voltage stabilizing device and a first voltage stabilizing matching resistor; The first controllable precision voltage stabilizing device has an anode, a cathode, and a reference electrode, the anode of the first controllable precision voltage stabilizing device is grounded, the cathode thereof is connected to the first pulse signal input terminal via the first voltage stabilizing matching resistor, the reference electrode and the cathode thereof are connected to form a first voltage stabilizing output terminal, and the first voltage stabilizing output terminal is connected to the second signal input terminal of the first operational amplifier; The voltage stabilizing circuit is used to convert the first pulse signal into a reference voltage signal with a constant amplitude and transmit it to the second signal input terminal of the first operational amplifier.

6. The light source driving circuit according to claim 2, wherein: The constant current control module further includes a current detection circuit, which includes a second operational amplifier, a first conversion resistor and a first feedback resistor; The second operational amplifier includes a third signal input terminal, a fourth signal input terminal and a second signal output terminal, The third signal input terminal is grounded, the fourth signal input terminal is connected to the first sampling node through the first conversion resistor, the second signal output terminal is connected to the first signal input terminal of the first operational amplifier; the first feedback resistor is connected between the second signal output terminal and the third signal input terminal.

7. The light source driving circuit according to any one of claims 1 to 6, characterized in that: It also includes a constant voltage control module, wherein the connection between the second load connection terminal and the switch module forms a second sampling node; The constant voltage control module has a second sampling terminal, a third driving input terminal and a voltage feedback output terminal, wherein the second sampling terminal is connected to the second sampling node and is used to receive the second sampling signal of the load driving circuit, the third driving input terminal is used to be connected to the first pulse signal output terminal of the controller to receive the first pulse signal, and the voltage feedback output terminal is connected to the voltage sampling terminal of the power supply module; The constant voltage control module is used to receive the second sampling signal and the first pulse signal output by the controller, and generate a voltage feedback signal according to the second sampling signal and the first pulse signal, and output the voltage feedback signal to the voltage sampling terminal of the power supply module. The power supply module receives the voltage feedback signal and outputs a corresponding power drive signal to the first load connection terminal, where the power drive signal is used to provide driving power for the load light source.

8. The light source driving circuit according to claim 7, wherein: The constant voltage control module includes a first voltage comparator; the first voltage comparator includes a fifth signal input terminal, a sixth signal input terminal and a third signal output terminal; The fifth signal input terminal is connected to the second sampling terminal to receive the second sampling signal, the sixth signal input terminal is the third driving input terminal, and is used to be connected to the first pulse signal output terminal of the controller, and the third signal output terminal is the voltage feedback output terminal, and is used to be connected to the voltage sampling terminal of the power module; If the voltage value of the fifth signal input terminal is less than the preset reference voltage value of the sixth signal input terminal, the third signal output terminal outputs a high-level voltage feedback signal to the voltage sampling terminal of the power module; If the voltage value of the fifth signal input terminal is greater than the preset reference voltage value of the sixth signal input terminal, the third signal output terminal outputs a low-level voltage feedback signal to the voltage sampling terminal of the power module; The power supply module receives the high-level voltage feedback signal and outputs a power supply drive signal with a first preset voltage value to the first load connection end. The power supply module receives the low-level voltage feedback signal and outputs a power supply drive signal with a second preset voltage value to the first load connection end.

9. The light source driving circuit according to claim 8, wherein: The constant voltage control module further includes a voltage follower circuit, and the voltage follower circuit includes a first diode, a first resistor, a second resistor and a third resistor; The cathode of the first diode serves as the second sampling terminal, the cathode of the first diode is connected to the second sampling node, the anode of the first diode is connected to the fifth signal input terminal through a first resistor and a second resistor, and the connection end of the first resistor and the second resistor is connected to a bias voltage source through the third resistor.

10. The light source driving circuit according to claim 8, wherein: The constant voltage control module further includes a reference voltage circuit; the sixth signal input terminal of the first voltage comparator is connected to a bias voltage source through the reference voltage circuit; The reference voltage circuit includes a fourth resistor, a fifth resistor and a sixth resistor; The sixth signal input terminal of the first voltage comparator is connected to the bias voltage source through the sixth resistor and the fifth resistor, the first terminal of the fourth resistor is connected to the fifth resistor and the sixth resistor, and the second terminal thereof is grounded; The fourth resistor and the fifth resistor form a voltage divider circuit, which divides the bias voltage source and transmits the divided voltage to the sixth signal input terminal through the sixth resistor.

11. The light source driving circuit according to claim 10, wherein: The sixth signal input terminal of the first voltage comparator is connected to the first pulse signal input terminal through the reference voltage circuit. The reference voltage circuit includes a second controllable precision voltage source, a second diode and a seventh resistor; The anode of the second controllable precision voltage source is grounded, and the cathode thereof is connected to the sixth signal input terminal of the first voltage comparator through the second diode and the sixth resistor. The reference electrode thereof is connected to the cathode and then connected to the first pulse signal input terminal through the seventh resistor.

12. The light source driving circuit according to any one of claims 8 to 11, characterized in that: The constant voltage control module further includes a voltage buffer circuit; The voltage buffer circuit includes a third diode, a fourth diode and an energy storage capacitor; the cathode of the third diode is connected to the third signal output end of the first voltage comparator, and its anode is connected to the cathode of the fourth diode, the anode of the fourth diode is the voltage feedback output end, the anode of the fourth diode is connected to the voltage sampling end of the power supply module, the first end of the energy storage capacitor is connected to the third diode and the fourth diode, and the second end is grounded.

13. A light source device, characterized in that: Comprising a controller, an LED light source, and a light source driving circuit according to any one of claims 1 to 12; The LED light source is connected in series to the light source driving circuit to form a load driving loop. The controller is used to output a pulse signal to the light source driving circuit to control the LED light source to light up and operate in a constant current state or to turn it off.

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