Driving circuits and electronic equipment

Abstract

The present application belongs to the field of electronic circuit technology, and particularly relates to a driving circuit and an electronic device, wherein the driving circuit includes a driving module, a switch module and a pre-feedback module, wherein the driving module is used to access the voltage of an input power supply and output a constant current to the load according to feedback, the switch module is connected to the load and the driving module, the input end of the switch module is used to access a control signal and connect or disconnect the power supply circuit of the load according to the control signal, the pre-feedback module is connected to the driving module, the input end of the pre-feedback module is used to access the control signal, and the pre-feedback module is used to provide a pre-feedback signal according to the control signal, so that the output of the driving module is maintained within a preset range when the load is not connected. The problem of peak glitch current generated at the moment of load connection due to the hysteresis of output feedback in traditional driving circuits is solved.

Description

Technical Field

[0001] The present application belongs to the field of electronic circuit technology, and in particular to drive circuits and electronic equipment. Background Art

[0002] The vertical cavity surface emitting laser (VCSEL) in 3D structured light technology is a commonly used semiconductor laser in 3D structured light technology. Semiconductor lasers work by direct carrier injection. The stability of the injected current has a direct and obvious impact on the output of the laser. Therefore, the driving technology of VCSEL usually adopts a constant current driving method, which usually requires high output current stability, small surge current and small ripple.

[0003] When using a constant current driver chip to drive a VCSEL, it is generally necessary to add a switch circuit to convert the continuous drive signal of the constant current driver chip into a pulse drive signal. This type of constant current driver chip generally obtains feedback voltage through a feedback resistor to output a constant current. The adjustment process of the constant current based on feedback has a lag, resulting in a peak glitch current when the chip drives the switch. This instantaneous peak glitch current seriously reduces the reliability and life of the VCSEL, and also causes a certain impact on the power supply system. Summary of the invention

[0004] In view of this, embodiments of the present application provide a drive circuit and an electronic device, aiming to solve the problem of peak glitch current generated when the load is turned on due to the hysteresis of output feedback in traditional drive circuits.

[0005] A first aspect of an embodiment of the present application provides a driving circuit, comprising: a driving module, used to access an input voltage and output a constant current to a load according to a feedback signal; a switch module, connected to the load and the driving module, the input end of the switch module being used to access a control signal, the switch module connecting a power supply circuit of the load when the control signal is in a first state, and providing the feedback signal to the driving module, and disconnecting the power supply circuit of the load when the control signal is in a second state; and a pre-feedback module, connected to the driving module, the input end of the pre-feedback module being used to access the control signal, outputting a pre-feedback signal to the driving module when the control signal is in the second state, and stopping outputting the pre-feedback signal when the control signal is in the first state; wherein the driving module is also used to maintain its output within a preset range according to the pre-feedback signal when the power supply circuit of the load is not connected.

[0006] In one of the embodiments, the voltage amplitude of the pre-feedback signal is in the range of 0.9 to 1.1 times the voltage amplitude of the feedback signal.

[0007] In one embodiment, the pre-feedback module includes a first switch circuit, an impedance matching circuit and a voltage divider circuit; the impedance matching circuit is connected in series between the input end of the pre-feedback module and the control end of the first switch circuit, the voltage divider circuit is connected in series between the first conduction end of the first switch circuit and the feedback end of the driving module, and the second conduction end of the first switch circuit is connected to a voltage stabilizing source; the impedance matching circuit is used to match the voltage of the control end of the first switch circuit, the voltage divider circuit is used to configure the voltage amplitude of the pre-feedback signal, and the first switch circuit is used to provide the driving module with a pre-feedback signal for maintaining a stable output when the power supply circuit of the load is disconnected under the control of the control signal.

[0008] In one embodiment, the first switch circuit includes a first switch tube, the impedance matching circuit includes a matching resistor, and the voltage divider circuit includes a voltage divider resistor; the matching resistor is connected in series between the input end of the pre-feedback module and the control end of the first switch tube, the voltage divider resistor is connected in series between the first conduction end of the first switch tube and the feedback end of the driving module, and the second conduction end of the first switch tube is connected to a voltage stabilizing source.

[0009] In one embodiment, the first switch tube is a PNP transistor or a PMOS tube.

[0010] In one embodiment, the switch module includes a second switch tube, a first resistor and a second resistor; the first conduction end of the second switch tube is connected to the load, the second conduction end of the second switch tube is connected to the driving module, the control end of the second switch tube is connected to the first end of the first resistor and the first end of the second resistor, the second end of the first resistor is used to access the control signal, and the second end of the second resistor is grounded; the second switch tube is used to be turned on when the control signal is in the first state, and to be turned off when the control signal is in the first state.

[0011] In one embodiment, the second switch tube is an NMOS tube.

[0012] In one embodiment, the driving module includes a constant current driving chip; the feedback pin of the constant current driving chip is connected to the switch module and the pre-feedback module, the input pin of the constant current driving chip is used to access the input voltage, and the output pin of the constant current driving chip is used to output the constant current.

[0013] In one embodiment, the driving module also includes a first feedback resistor, a second feedback resistor and a third feedback resistor; the first end of the first feedback resistor is connected to the feedback pin of the constant current driving chip, the second end of the first feedback resistor is connected to the switch module, and the second feedback resistor and the third feedback resistor are connected in parallel and in series between the second end of the first feedback resistor and ground.

[0014] A second aspect of the embodiments of the present application provides an electronic device, comprising the driving circuit provided by the first aspect of the embodiments of the present application, wherein the load is a laser light source or an LED light source.

[0015] Compared with the traditional technical solution, the beneficial effect of the present application is: by setting a pre-feedback module, when the switch module is not connected to the power supply circuit of the load, that is, the load stops working and cannot provide a feedback signal to the driving module, the pre-feedback module provides a pre-feedback signal to the driving module, so that the driving module can maintain its output within a preset range according to the pre-feedback signal. In this way, when the switch module connects to the power supply circuit of the load, no glitch current will appear in the output of the driving module, which solves the problem of peak glitch current generated at the moment the load is connected due to the hysteresis of the output feedback of the driving circuit with feedback. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 A schematic diagram of a driving circuit provided in one embodiment of the present application;

[0018] Figure 2 A schematic diagram of a driving circuit provided in another embodiment of the present application;

[0019] Figure 3 A schematic diagram of the circuit principle of a driving circuit provided in one embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0022] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0024] See also Figure 1 As shown, the first aspect of the embodiment of the present application provides a driving circuit 10, which is connected to a load 20 and is used to drive the load 20, wherein the driving circuit 10 includes a driving module 100, a switch module 200 and a pre-feedback module 300. The driving module 100 is used to access the input voltage of the input power supply VCC and output a constant current to the load 20 according to a feedback signal. It can be understood that the feedback here is the feedback voltage output by the driving module 100 to the load 20.

[0025] The switch module 200 is connected to the load 20 and the driving module 100. The input end of the switch module 200 is used to access the control signal. When the control signal is in the first state, the switch module 200 connects the power supply circuit of the load 20, that is, the load 20 starts to work, and provides a feedback signal to the driving module 100. When the control signal is in the second state, the switch module 200 disconnects the power supply circuit of the load 20, that is, the load 20 stops working. The pre-feedback module 300 is connected to the driving module 100. The input end of the pre-feedback module 300 is used to access the control signal. When the control signal is in the second state, the pre-feedback signal is output to the driving module 100. When the control signal is in the first state, the pre-feedback signal is stopped from being output. The pre-feedback signal is used to maintain the output of the driving module 100 within a preset range when the power supply circuit of the load 20 is not connected.

[0026] It can be understood that the control signal connected to the input end of the switch module 200 and the input end of the pre-feedback module 300 is the same control signal. When the load 20 stops working, the switch module 200 cannot provide a feedback voltage to the driving module 100, that is, the feedback voltage of the driving module 100 is zero. At this time, the pre-feedback module 300 can provide a pre-feedback signal to the driving module 100 to maintain the output of the driving module 100 within a preset range.

[0027] The driving circuit 10 provided in the first aspect of the embodiment of the present application is provided with a pre-feedback module 300. When the switch module 200 is not connected to the power supply circuit of the load 20, that is, the load 20 stops working and cannot provide a feedback signal to the driving module 100, the pre-feedback module 300 provides a pre-feedback signal to the driving module 100, so that the driving module 100 can maintain its output within a preset range according to the pre-feedback signal. In this way, when the switch module 200 is connected to the power supply circuit of the load 20, no glitch current will appear in the output of the driving module 100, thereby solving the problem of peak glitch current generated at the moment the load 20 is connected due to the hysteresis of the output feedback of the driving circuit with feedback.

[0028] In one embodiment, the first state is, for example, a high level signal, and the second state is, for example, a low level signal state.

[0029] In one embodiment, the voltage amplitude of the pre-feedback signal is within the range of 0.9 to 1.1 times the voltage amplitude of the feedback signal, and the voltage amplitude of the pre-feedback signal provided by the pre-feedback module 300 to the driving module 100 is consistent with the voltage amplitude of the feedback signal after the switch module 200 is connected to the load 20 and starts working. It can be understood that in the actual operation of the driving circuit 10, the voltage amplitude of the pre-feedback signal may not be exactly equal to the voltage amplitude of the feedback signal when the load 20 works normally, and the voltage amplitude of the pre-feedback signal will have a certain fluctuation, so that the driving module 100 can provide a voltage within the tolerable range of the load 20 according to the pre-feedback signal within this range, and will not damage the service life of the load 20.

[0030] See also Figure 2In one embodiment, the pre-feedback module 300 includes a first switch circuit 320, an impedance matching circuit 310 and a voltage divider circuit 330. The impedance matching circuit 310 is connected in series between the input end of the pre-feedback module 300 and the control end of the first switch circuit 320, the voltage divider circuit 330 is connected in series between the first conduction end of the first switch circuit 320 and the feedback end FEED of the driving module 100, and the second conduction end of the first switch circuit 320 is connected to the voltage regulator source VDD. Among them, the first switch circuit 320 is used to provide a pre-feedback signal for maintaining a stable output to the driving module 100 when the power supply circuit of the load 20 is disconnected under the control of the control signal, the impedance matching circuit 310 is used to match the voltage of the control end of the first switch circuit 320, and the voltage divider circuit 330 is used to configure the voltage amplitude of the pre-feedback signal given to the feedback end FEED of the driving module 100, that is, by adjusting the resistance of the voltage divider circuit 330, the voltage amplitude of the pre-feedback signal required by the user can be adjusted.

[0031] See also Figure 3 In one embodiment, the first switch circuit 320 includes a first switch tube Q1, the impedance matching circuit 310 includes a matching resistor R1, and the voltage divider circuit 330 includes a voltage divider resistor R2.

[0032] The matching resistor R1 is connected in series between the input end of the pre-feedback module 300 and the control end of the first switch tube Q1, the voltage-dividing resistor R2 is connected in series between the first conduction end of the first switch tube Q1 and the feedback end FEED of the driving module 100, and the second conduction end of the first switch tube Q1 is connected to the voltage stabilizing source VDD. The matching resistor R1 is used to stabilize the voltage of the control end of the first switch tube Q1, the first switch tube Q1 is used to be cut off when the control signal of the input end PWM is a high-level signal, and to be turned on when the control signal of the input end PWM is a low-level signal, and the voltage-dividing resistor R2 is used to configure the voltage amplitude of the pre-feedback signal, that is, by adjusting the resistance value of the voltage-dividing circuit 330, the voltage amplitude of the pre-feedback signal required by the user can be adjusted.

[0033] See also Figure 3 In one embodiment, the first switch tube Q1 is a PNP transistor. Figure 3 The base of the first switch tube Q1 is connected to the input end of the pre-feedback module 300 through the matching resistor R1, that is, it is used to access the control signal of the input end PWM, the collector of the first switch tube Q1 is connected to the feedback end FEED of the driving module 100 through the voltage dividing resistor R2, and the emitter of the first switch tube Q1 is connected to the voltage regulator source VDD. In some embodiments, the voltage regulator source VDD is, for example, 1.8V. It can be understood that in some embodiments, the first switch tube Q1 can also use a PMOS tube.

[0034] See also Figure 3In one embodiment, the switch module 200 includes a second switch tube Q2, a first resistor, and a second resistor. The first conduction end of the second switch tube Q2 is connected to the load 20, the second conduction end of the second switch tube Q2 is connected to the driving module 100, the control end of the second switch tube Q2 is connected to the first end of the first resistor R3 and the first end of the second resistor R4, the second end of the first resistor R3 is used to access the control signal of the input end PWM, and the second end of the second resistor R4 is grounded. The second switch tube Q2 is used to be turned on when the control signal of the input end PWM is a high level signal, and turned off when the control signal of the input end PWM is a low level signal.

[0035] See also Figure 3 In one embodiment, the second switch tube Q2 is an NMOS tube. Figure 3 The drain of the second switch tube Q2 is connected to the negative electrode of the load 20, the source of the second switch tube Q2 is connected to the driving module 100, and the gate of the second switch tube Q2 is connected to the first end of the first resistor R3 and the first end of the second resistor R4.

[0036] It should be noted that, since the second switch tube Q2 is an NMOS tube, it is turned on when the control signal of the input end PWM is a high-level signal, and is turned off when the control signal of the input end PWM is a low-level signal, and the first switch tube Q1 is a PNP-type triode, and the first switch tube Q1 is turned off when the control signal of the input end PWM is a high-level signal, and is turned on when the control signal of the input end PWM is a low-level signal. In this way, the switch module 200 and the pre-feedback module 300 are controlled by the same control signal, and when the switch module 200 starts to work without connecting to the load 20, the first switch tube Q1 of the pre-feedback module 300 is turned on to provide a pre-feedback signal to the feedback end FEED of the driving module 100. When the switch module 200 is turned on, the driving module 100 will not have a peak glitch current because there is no feedback signal at its feedback end FEED, and after the load 20 starts to work, the pre-feedback module 300 will stop providing the pre-feedback signal. Using the same control signal makes the circuit easier to control, preventing the switch module 200 and the pre-feedback module 300 from using two control signals to control the circuit respectively, which causes conflicts in the circuit, thereby improving the stability of the circuit.

[0037] See also Figure 3 In one embodiment, the driving module 100 includes a constant current driving chip 110. The feedback pin FB of the constant current driving chip 110 is connected to the switch module 200 and the pre-feedback module 300, the input pin VIN of the constant current driving chip 110 is used to access the input voltage of the input power supply VCC, and the output pin LX of the constant current driving chip 110 is used to output a constant current to drive the load 20.

[0038] See also Figure 3 In one embodiment, the driving module 100 further includes a first feedback resistor R5, a second feedback resistor R6, and a third feedback resistor R7. The first end of the first feedback resistor R5 is connected to the feedback pin FB of the constant current driving chip 110, the second end of the first feedback resistor R5 is connected to the switch module 200, and the second feedback resistor R6 and the third feedback resistor R7 are connected in parallel and in series between the second end of the first feedback resistor R5 and the ground. The first feedback resistor R5, the second feedback resistor R6, and the third feedback resistor R7 act as a voltage divider to provide a feedback voltage to the feedback pin FB of the constant current driving chip 110.

[0039] See also Figure 3 In one embodiment, the driving module 100 further includes an input inductor L1, an input capacitor C1, an output inductor L2, and an output capacitor C3. The input inductor L1 is connected in series between the input end of the constant current driving chip 110, that is, the input pin VIN, and the input power supply VCC. The input capacitor C1 is connected in series between the input end of the constant current driving chip 110, that is, the input pin VIN, and the ground. The input inductor L1 and the input capacitor C1 are used to stabilize the input voltage of the output constant current driving chip 110. The first end of the output inductor L2 is connected to the output end of the constant current driving chip 110, that is, the output pin LX. The second end of the output inductor L2 is connected to the positive electrode of the load 20. The output capacitor C3 is connected in series between the second end of the output inductor L2 and the ground. The output inductor L2 is used to store energy to stabilize the output current, and the output capacitor C3 plays a filtering role.

[0040] Further, see Figure 3 , the enable pin EN of the constant current driver chip 110 is connected in series with the resistor R9 to access the enable signal of the constant current driver chip 110 or the pulse signal DIM, and the pulse signal DIM is used to adjust the output current of the constant current driver chip 110. In one embodiment, the load 20 is a light-emitting load 20, such as a light-emitting diode (LED), a laser, a fluorescent lamp, etc., and the pulse signal DIM can adjust the brightness of the load 20. A capacitor C5 is also connected in series between the pin BS and the output pin LX of the constant current driver chip 110, and the capacitor C5 is the bootstrap capacitor of the constant current driver chip 110. The capacitor C2 is connected in series between the enable pin EN of the constant current driver chip 110 and the ground, and the capacitor C2 plays a filtering role. The capacitor C4 is connected in series between the second end of the output inductor L2 and the ground, and the capacitor C4 plays a filtering role like the output capacitor C3.

[0041] In order to better illustrate the working principle of the driving circuit 10 provided in the embodiment of the present application, the following description is given in combination with the actual working condition of the circuit.

[0042] See also Figure 3When the control signal of the input terminal PWM is at a low level, the gate of the second switch tube Q2 is at a low level, the second switch tube Q2 is turned off, the load 20 does not work, and the feedback pin FB of the constant current driver chip 110 cannot obtain the feedback signal. At the same time, the emitter of the first switch tube Q1 is connected to the 1.8V voltage regulator source VDD, and the control signal of the input terminal PWM connected to the base of the first switch tube Q1 is at a low level, the first switch tube Q1 is turned on, and the voltage of the voltage regulator source VDD is divided by Q1, R2, R5, R6 and R7 and then applied to the feedback pin FB of the constant current driver chip 110. The pin FB forms a pre-feedback signal, which can be made consistent with the feedback signal when the load 20 is working normally by adjusting the resistance value of R2. Due to the existence of the pre-feedback signal, the voltage output by the constant current driver chip 110 at this time is also matched with the load 20. When the control signal of the input terminal PWM is high, the second switch tube Q2 is turned on, the load 20 starts to work, and the feedback pin FB of the constant current driver chip 110 obtains a normal feedback signal. At the same time, the first switch tube Q1 is turned off, and the pre-feedback module 300 stops outputting the pre-feedback signal. Before and after the second switch tube Q2 is turned on, the output voltage of the constant current driver chip 110 is always matched with the load 20. The driver module 100 will not have a peak glitch current because there is no feedback signal at its feedback terminal FEED, so that the driver module 100 provides a voltage within the tolerance range of the load 20, which will not damage the service life of the load 20, improve the service life and reliability of the load 20, and reduce the impact on the external power supply system.

[0043] The driving circuit 10 provided in the first aspect of the embodiment of the present application is provided with a pre-feedback module 300. When the switch module 200 is not connected to the power supply circuit of the load 20, that is, the load 20 stops working and cannot provide a feedback signal to the driving module 100, the pre-feedback module 300 provides a pre-feedback signal to the driving module 100, so that the driving module 100 can maintain its output within a preset range according to the pre-feedback signal. In this way, when the switch module 200 is connected to the power supply circuit of the load 20, no glitch current will appear in the output of the driving module 100, thereby solving the problem of peak glitch current generated at the moment the load 20 is connected due to the hysteresis of the output feedback of the driving circuit with feedback.

[0044] The second aspect of the embodiment of the present application provides an electronic device, the electronic device includes the driving circuit 10 provided in the first aspect of the embodiment of the present application, wherein the load 20 is a laser light source or an LED light source. In some embodiments, the load 20 is a vertical cavity surface emitting laser (VCSEL).

[0045] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A driving circuit, characterized in that: include: A drive module is used to receive input voltage and output a constant current to the load according to a feedback signal; a switch module connected to the load and the driving module, wherein an input end of the switch module is used to receive a control signal, the switch module connects a power supply circuit of the load when the control signal is in a first state and provides the feedback signal to the driving module, and disconnects the power supply circuit of the load when the control signal is in a second state; and A pre-feedback module connected to the driving module, wherein the input end of the pre-feedback module is used to receive the control signal, output the pre-feedback signal to the driving module when the control signal is in the second state, and stop outputting the pre-feedback signal when the control signal is in the first state; The driving module is further configured to maintain its output within a preset range according to the pre-feedback signal when the power supply circuit of the load is not connected.

2. The driving circuit according to claim 1, characterized in that: The voltage amplitude of the pre-feedback signal is in the range of 0.9 to 1.1 times the voltage amplitude of the feedback signal.

3. The driving circuit according to claim 1, wherein: The pre-feedback module includes a first switch circuit, an impedance matching circuit and a voltage divider circuit; The impedance matching circuit is connected in series between the input end of the pre-feedback module and the control end of the first switch circuit, the voltage divider circuit is connected in series between the first conduction end of the first switch circuit and the feedback end of the driving module, and the second conduction end of the first switch circuit is connected to a voltage stabilizing source; The impedance matching circuit is used to match the voltage of the control end of the first switching circuit, the voltage divider circuit is used to configure the voltage amplitude of the pre-feedback signal, and the first switching circuit is used to provide the driving module with a pre-feedback signal for maintaining a stable output when the power supply circuit of the load is disconnected under the control of the control signal.

4. The driving circuit according to claim 3, characterized in that: The first switch circuit includes a first switch tube, the impedance matching circuit includes a matching resistor, and the voltage divider circuit includes a voltage divider resistor; The matching resistor is connected in series between the input end of the pre-feedback module and the control end of the first switch tube, the voltage-dividing resistor is connected in series between the first conduction end of the first switch tube and the feedback end of the driving module, and the second conduction end of the first switch tube is connected to a voltage stabilizing source.

5. The driving circuit according to claim 4, characterized in that: The first switch tube is a PNP transistor or a PMOS tube.

6. The driving circuit according to claim 1, characterized in that: The switch module includes a second switch tube, a first resistor and a second resistor; The first conducting end of the second switch tube is connected to the load, the second conducting end of the second switch tube is connected to the driving module, the control end of the second switch tube is connected to the first end of the first resistor and the first end of the second resistor, the second end of the first resistor is used to access the control signal, and the second end of the second resistor is grounded; The second switch tube is used to be turned on when the control signal is in the first state, and to be turned off when the control signal is in the first state.

7. The driving circuit according to claim 6, characterized in that: The second switch tube is an NMOS tube.

8. The driving circuit according to any one of claims 1 to 7, characterized in that: The driving module includes a constant current driving chip; The feedback pin of the constant current driving chip is connected to the switch module and the pre-feedback module, the input pin of the constant current driving chip is used to access the input voltage, and the output pin of the constant current driving chip is used to output the constant current.

9. The driving circuit according to claim 8, characterized in that: The driving module further includes a first feedback resistor, a second feedback resistor and a third feedback resistor; The first end of the first feedback resistor is connected to the feedback pin of the constant current drive chip, the second end of the first feedback resistor is connected to the switch module, and the second feedback resistor and the third feedback resistor are connected in parallel and in series between the second end of the first feedback resistor and ground.

10. An electronic device, characterized in that: The drive circuit comprises the drive circuit as claimed in any one of claims 1 to 9, wherein the load is a laser light source or an LED light source.

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