Laser driving circuit and laser radar

Abstract

A laser driving circuit and a laser radar belong to the technical field of electronic circuits, when a first driving signal is at a low level, a charging circuit conducts a power supply direct current flowing out from an energy storage circuit to a power ground so that the energy storage circuit performs charging according to the power supply direct current to generate a charging voltage; when the first driving signal is at a high level, the energy storage circuit bootstraps the power supply voltage according to the charging voltage so as to output bootstrap voltage; the low-side driving circuit is connected with a second driving signal, when the first driving signal is at a high level, the second driving signal is converted into the first driving signal according to the bootstrap voltage, so that the switching circuit outputs the power supply voltage to the light source to lighten the light source, and when the first driving signal is at a low level, the second driving signal is converted into the first driving signal according to the bootstrap voltage. Converting the second driving signal into a first driving signal according to the charging voltage; the switching circuit comprises an N-type switching tube; when the light source common cathode is grounded, the turn-off speed is improved, and the circuit size is reduced.

Description

Technical Field

[0001] The present application belongs to the field of electronic circuit technology, and in particular, relates to a laser driving circuit and a laser radar. Background Art

[0002] As vehicle-mounted LiDAR systems are increasingly used in assisted driving of new energy vehicles, car companies have higher and higher requirements for the ranging capability, scanning resolution and other indicators and cost control of vehicle-mounted LiDAR, which ultimately leads to higher and higher repetition rates of single-channel light emission in the design of vehicle-mounted LiDAR, and higher and higher light output power, which also causes the light source to heat up more seriously. Usually, existing lasers generally use low-side drivers to drive N-type metal-oxide-semiconductor (NMOS) laser tubes to emit light. Since the laser tube is not a common cathode grounded topology, it is impossible to complete the rapid heat treatment of the light source well, and the working stability of the light source will be greatly affected, especially in high temperature environments. The performance is extremely unstable. Most lasers have reduced transmission power when used in the highest temperature environment in summer, resulting in reduced ranging performance.

[0003] In order to solve the above common cathode grounding heat dissipation problem, the relevant laser driving circuit uses the existing high-side driver to drive the NMOS to turn on and control the laser tube to emit light. Although it can solve the problem of common cathode grounding heat dissipation of the light source, the minimum driving pulse width of the existing high-side driver is generally above 12ns, which is not conducive to ranging and correction under the receiving system of single-photon avalanche diode (SPAD) or SIPM. At the same time, the driving circuit is large in size, which is not conducive to circuit integration and miniaturization. That is: using a high-side driver to realize the common cathode grounding of the light source, although the circuit topology is simple and the general conduction speed can meet the use requirements, the turn-off rate is generally hundreds of nanoseconds or microseconds, which cannot meet the application requirements of the laser.

[0004] Therefore, when the related laser driving circuit works with the light source common cathode grounded, the shutdown speed is slow and the circuit size is large. Utility Model Content

[0005] The purpose of the present application is to provide a laser driving circuit and a laser radar, aiming to solve the problem that the related laser driving circuit has a slow shutdown speed and a large circuit size when the light source is working with a common cathode grounding.

[0006] The embodiment of the present application provides a laser driving circuit, including:

[0007] A switch circuit is configured to output a supply voltage to the light source to light up the light source when the first drive signal is at a high level; the switch circuit includes an N-type switch tube;

[0008] an energy storage circuit, connected to the switch circuit, configured to be connected to a power supply DC, to be charged according to the power supply DC to generate a charging voltage when the first drive signal is at a low level, and to bootstrap the power supply voltage according to the charging voltage to output a bootstrap voltage when the first drive signal is at a high level;

[0009] a charging circuit connected to the energy storage circuit and the switch circuit, and configured to conduct the power supply DC current flowing out of the energy storage circuit to a power ground when the first drive signal is at a low level;

[0010] A low-side drive circuit is connected to the switch circuit, the energy storage circuit and the charging circuit, and is configured to receive a second drive signal, convert the second drive signal into the first drive signal according to the bootstrap voltage when the first drive signal is at a high level, and convert the second drive signal into the first drive signal according to the charging voltage when the first drive signal is at a low level.

[0011] In one embodiment, it also includes:

[0012] A first level conversion circuit is connected to the switch circuit, the energy storage circuit, the charging circuit and the low-side drive circuit, and is configured to receive a third drive signal. When the first drive signal is at a high level, the third drive signal is raised and isolated according to the supply voltage to output the second drive signal. When the first drive signal is at a low level, the third drive signal is isolated to output the second drive signal.

[0013] In one embodiment, it also includes:

[0014] a second level conversion circuit, connected to the switch circuit, the energy storage circuit, the charging circuit and the low-side drive circuit, and configured to receive a fourth drive signal, and when the first drive signal is at a high level, to raise and isolate the fourth drive signal according to the supply voltage to output the fifth drive signal, and when the first drive signal is at a low level, to isolate the fourth drive signal to output the fifth drive signal;

[0015] The low-side drive circuit is specifically configured to convert the second drive signal and the fifth drive signal into the first drive signal according to the bootstrap voltage when the first drive signal is at a high level, and to convert the second drive signal and the fifth drive signal into the first drive signal according to the charging voltage when the first drive signal is at a low level.

[0016] In one embodiment, it also includes:

[0017] The control circuit is connected to the first level conversion circuit and is configured to provide the third driving signal.

[0018] In one embodiment, it also includes:

[0019] A unidirectional conduction circuit, connected to the energy storage circuit and the low-side drive circuit, configured to conduct unidirectional conduction of the power supply DC;

[0020] The energy storage circuit is specifically configured to charge the unidirectionally conducted DC power supply to generate a charging voltage when the first drive signal is at a low level, and to bootstrap the supply voltage according to the charging voltage to output a bootstrap voltage when the first drive signal is at a high level.

[0021] In one of the embodiments, the low-side driving circuit includes a low-side driver;

[0022] The power supply terminal of the low-side driver serves as a charging voltage input terminal of the low-side driver circuit and a bootstrap voltage input terminal of the low-side driver circuit, and is connected to the energy storage circuit to access the charging voltage and the bootstrap voltage;

[0023] The negative logic level terminal of the low-side driver and the ground terminal of the low-side driver serve as the signal ground of the low-side driver circuit; when the first drive signal is at a high level, the signal ground is the power supply voltage; when the first drive signal is at a high level, the signal ground is the power ground;

[0024] The positive logic level terminal of the low-side driver is used as the second drive signal input terminal of the low-side drive circuit to receive the second drive signal;

[0025] The pull-up gate driving end of the low-side driver and the pull-down gate driving end of the low-side driver serve together as the first driving signal output end of the low-side driving circuit, and are connected to the switch circuit to output the first driving signal.

[0026] In one embodiment, the N-type switch tube is a first NMOS tube;

[0027] The gate of the first NMOS tube serves as the first drive signal input terminal of the switch circuit, and is connected to the low-side drive circuit to receive the first drive signal; the drain of the first NMOS tube serves as the power supply voltage input terminal of the switch circuit to receive the power supply voltage; the source of the first NMOS tube serves as the power supply voltage output terminal of the switch circuit, and is connected to the light source to output the power supply voltage.

[0028] In one embodiment, the charging circuit includes a second NMOS transistor;

[0029] The gate of the second NMOS tube serves as the fourth drive signal input terminal of the charging circuit to receive the fourth drive signal; the drain of the second NMOS tube serves as the DC power input terminal of the charging circuit and is connected to the energy storage circuit to receive the DC power flowing out of the energy storage circuit; the source of the second NMOS tube is connected to the power ground;

[0030] The fourth driving signal is in anti-phase with the first driving signal.

[0031] In one embodiment, the charging circuit includes a first resistor;

[0032] The first end of the first resistor serves as a DC power supply input end of the charging circuit and is connected to the energy storage circuit to receive the DC power supply flowing out of the energy storage circuit; the second end of the first resistor is connected to a power ground.

[0033] In one of the embodiments, the first level conversion circuit includes a first magnetic element;

[0034] The first input end of the first magnetic element serves as the third driving signal input end of the first level conversion circuit to receive the third driving signal; the second input end of the first magnetic element is connected to the power ground;

[0035] The first output end of the first magnetic element serves as the second drive signal output end of the first level conversion circuit and is connected to the low-side drive circuit to output the second drive signal;

[0036] The second output end of the first magnetic element serves as the signal ground of the first level conversion circuit; when the first drive signal is at a high level, the signal ground is the supply voltage; when the first drive signal is at a low level, the signal ground is the power ground or is in a floating state.

[0037] In one of the embodiments, the first level conversion circuit includes a first photocoupler and a first current limiting resistor;

[0038] The positive electrode of the first photocoupler is used as the third driving signal input terminal of the first level conversion circuit to receive the third driving signal; the negative electrode of the first photocoupler is connected to the power ground;

[0039] The emitter of the first photocoupler and the first end of the first current limiting resistor serve together as the second drive signal output end of the first level conversion circuit, and are connected to the low-side drive circuit to output the second drive signal;

[0040] The second end of the first current limiting resistor serves as a signal ground of the first level conversion circuit; when the first drive signal is at a high level, the signal ground is the power supply voltage; when the first drive signal is at a low level, the signal ground is a power ground or in a floating state;

[0041] The collector of the first photoelectric coupler serves as a power supply DC input terminal of the first level conversion circuit and is connected to the energy storage circuit to access the power supply DC.

[0042] An embodiment of the utility model further provides a laser radar, which includes a light source and the above-mentioned laser driving circuit.

[0043] Compared with the prior art, the embodiments of the utility model have the following beneficial effects: when the first drive signal is at a low level, the power supply DC flowing out through the energy storage circuit is conducted to the power supply ground; the energy storage circuit is charged according to the power supply DC to generate a charging voltage; the low-side drive circuit converts the second drive signal into the first drive signal according to the charging voltage; at this time, the power supply potential (charging voltage) of the low-side drive circuit is not self-bootstrapped, and the output voltage difference is a low-level first drive signal of 0, wherein the voltage difference is the voltage difference between the first drive signal and the signal ground; thus, the switch circuit is turned off and the light source stops working; when the first drive signal is at a high level, the charging circuit converts the power supply DC flowing out through the energy storage circuit to the first drive signal. The power supply is electrically connected to the power supply ground; the energy storage circuit bootstraps the power supply voltage according to the charging voltage to output the bootstrap voltage; the low-side driving circuit converts the second driving signal into the first driving signal according to the bootstrap voltage; at this time, the power supply potential (bootstrap voltage) of the low-side driving circuit is bootstrapped, and the first driving signal of the high level after bootstrap is output to the switching circuit, and the voltage of the first driving signal of the high level after bootstrap is the voltage at both ends of the energy storage circuit; the switching circuit outputs the power supply voltage to the light source to light the light source; therefore, the high-side driving of the light source is realized by the low-side driving circuit, that is, when the light source works with the common cathode grounded, the shutdown speed is improved and the circuit volume is reduced. In addition, while the bootstrap voltage increases the gate-source voltage of the N-type switching tube, it can also reduce the on-resistance of the N-type switching tube, thereby reducing heat loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical utility model in the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A schematic diagram of a structure of a laser driving circuit provided in one embodiment of the present application;

[0046] Figure 2 Another structural schematic diagram of a laser driving circuit provided in an embodiment of the present application;

[0047] Figure 3 Another structural schematic diagram of a laser driving circuit provided in an embodiment of the present application;

[0048] Figure 4 Another structural schematic diagram of a laser driving circuit provided in an embodiment of the present application;

[0049] Figure 5 Another structural schematic diagram of a laser driving circuit provided in an embodiment of the present application;

[0050] Figure 6 A partial exemplary circuit schematic diagram of a laser driving circuit provided in an embodiment of the present application;

[0051] Figure 7 Another partial exemplary circuit schematic diagram of a laser driving circuit provided in an embodiment of the present application;

[0052] Figure 8 Another partial exemplary circuit schematic diagram of a laser driving circuit provided in an embodiment of the present application;

[0053] Fig. 9 Another partial exemplary circuit schematic diagram of a laser driving circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0054] In order to make the technical problems, technical solutions and beneficial effects to be solved by 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] Figure 1 The structure diagram of the laser driving circuit provided by the preferred embodiment of the present application is shown. For the convenience of explanation, only the part related to the present embodiment is shown, which is described in detail as follows:

[0059] The laser driving circuit comprises a switch circuit 11 , a storage circuit 12 , a charging circuit 13 and a low-side driving circuit 14 .

[0060] The switch circuit 11 is configured to output the supply voltage VAA to the light source 90 to light up the light source 90 when the first driving signal PWM1 is at a high level; the switch circuit 11 includes an N-type switch tube.

[0061] The energy storage circuit 12 is connected to the switching circuit 11 and is configured to be connected to the power supply DC power VBB. When the first drive signal PWM1 is at a low level, it is charged according to the power supply DC power VBB to generate a charging voltage, and when the first drive signal PWM1 is at a high level, it bootstraps the power supply voltage VAA according to the charging voltage to output a bootstrap voltage.

[0062] The charging circuit 13 is connected to the energy storage circuit 12 and the switch circuit 11 , and is configured to conduct the power supply DC power VBB flowing out of the energy storage circuit 12 to the power ground when the first driving signal PWM1 is at a low level.

[0063] The low-side drive circuit 14 is connected to the switch circuit 11, the energy storage circuit 12 and the charging circuit 13, and is configured to receive the second drive signal PWM2. When the first drive signal PWM1 is at a high level, the second drive signal PWM2 is converted into the first drive signal PWM1 according to the bootstrap voltage, and when the first drive signal PWM1 is at a low level, the second drive signal PWM2 is converted into the first drive signal PWM1 according to the charging voltage.

[0064] In a specific implementation, the charging circuit 13 may include a switch tube or a resistor. The energy storage circuit 12 may include a capacitor. The low-side driving circuit 14 may include a low-side driver.

[0065] like Figure 2 As shown, the laser driving circuit further includes a first level conversion circuit 15 .

[0066] The first level conversion circuit 15 is connected to the switch circuit 11, the energy storage circuit 12, the charging circuit 13 and the low-side drive circuit 14, and is configured to receive the third drive signal PWM3. When the first drive signal PWM1 is at a high level, the third drive signal PWM3 is raised and isolated according to the power supply voltage VAA to output the second drive signal PWM2, and when the first drive signal PWM1 is at a low level, the third drive signal PWM3 is isolated to output the second drive signal PWM2.

[0067] As an example but not limitation, the first level conversion circuit 15 includes at least one of a common mode inductor, a first magnetic element, a first photocoupler, or a level converter.

[0068] Since the low-side drive circuit 14 uses the power supply voltage VAA as the signal ground when the first drive signal PWM1 is at a high level, the drive signal (first drive signal PWM1) input to the low-side drive circuit 14 is required to have a higher level, and the original drive signal (third drive signal PWM3) is usually output by a signal generator that can output a drive signal, such as a field programmable gate array (FPGA) or ARM, so that the level of the signal generator output signal (third drive signal PWM3) is lower than the requirement of the low-side drive circuit 14, so it is necessary to perform level conversion on the third drive signal PWM3 to output the first drive signal PWM1. Since the low-side drive circuit 14 uses the power supply ground as the signal ground when the first drive signal PWM1 is at a low level, it is only necessary to isolate the signal generator output signal (third drive signal PWM3) to output the first drive signal PWM1. In addition, the first level conversion circuit plays an isolation role to prevent the high voltage from flowing back into the low-side drive circuit 14 when the high-speed N-type switch tube is turned on, thereby damaging the low-side drive circuit 14.

[0069] like Figure 3 As shown, the laser driving circuit further includes a second level conversion circuit 18 .

[0070] The second level conversion circuit 18 is connected to the switching circuit 11, the energy storage circuit 12, the charging circuit 13 and the low-side driving circuit 14, and is configured to receive the fourth driving signal PWM4. When the first driving signal PWM1 is at a high level, the fourth driving signal PWM4 is raised and isolated according to the power supply voltage VAA to output the fifth driving signal PWM5, and when the first driving signal PWM1 is at a low level, the fourth driving signal PWM4 is isolated to output the fifth driving signal PWM5.

[0071] The low-side drive circuit is specifically configured to convert the second drive signal PWM2 and the fifth drive signal PWM5 into the first drive signal PWM1 according to the bootstrap voltage when the first drive signal PWM1 is at a high level, and to convert the second drive signal PWM2 and the fifth drive signal PWM5 into the first drive signal PWM1 according to the charging voltage when the first drive signal PWM1 is at a low level.

[0072] like Figure 4 As shown, the laser driving circuit further includes a control circuit 16 .

[0073] The control circuit 16 is connected to the first level conversion circuit 15 and is configured to provide a third driving signal PWM3.

[0074] like Figure 5 As shown, the laser driving circuit further includes a unidirectional conduction circuit 17 .

[0075] The unidirectional conduction circuit 17 is connected to the energy storage circuit 12 and the low-side driving circuit 14 and is configured to conduct unidirectional conduction to the power supply DC power VBB.

[0076] The energy storage circuit 12 is specifically configured to charge according to the unidirectionally conducted DC power supply VBB to generate a charging voltage when the first drive signal PWM1 is at a low level, and to bootstrap the power supply voltage VAA according to the charging voltage to output a bootstrap voltage when the first drive signal PWM1 is at a high level.

[0077] The unidirectional conducting circuit 17 may be a fast recovery diode with the same withstand voltage level as the N-type switch tube.

[0078] Since the power supply DC power VBB is unidirectionally conducted and then output to the energy storage circuit 12, current backflow when the bootstrap voltage is greater than the voltage of the power supply DC power VBB is prevented, thereby improving the stability and reliability of the laser driving circuit.

[0079] Figure 6 A partial exemplary circuit structure of a laser driving circuit provided by an embodiment of the utility model is shown. Figure 7 Another partial exemplary circuit structure of the laser driving circuit provided by the embodiment of the utility model is shown. For the convenience of description, only the part related to the embodiment of the utility model is shown, which is described in detail as follows:

[0080] like Figure 6 and Figure 7 As shown, the energy storage circuit 12 includes a first capacitor C1;

[0081] The first end of the first capacitor C1 serves as the bootstrap voltage output end of the energy storage circuit 12, and is connected to the low-side driver to output the bootstrap voltage; the first end of the first capacitor C1 and the second end of the first capacitor C1 serve as the charging voltage output end of the energy storage circuit 12, and are connected to the low-side driver to output the charging voltage.

[0082] like Figure 6 and Figure 7 As shown, the N-type switch tube is the first NMOS tube N1;

[0083] The gate of the first NMOS tube N1 serves as the first drive signal input terminal of the switch circuit 11, and is connected to the low-side drive circuit 14 to receive the first drive signal PWM1; the drain of the first NMOS tube N1 serves as the power supply voltage VAA input terminal of the switch circuit 11 to receive the power supply voltage VAA; the source of the first NMOS tube N1 serves as the power supply voltage VAA output terminal of the switch circuit 11, and is connected to the light source to output the power supply voltage VAA.

[0084] like Figure 6 and Figure 7 As shown, the low-side driving circuit 14 includes a low-side driver U1;

[0085] The power supply terminal VDD of the low-side driver U1 is used as the charging voltage input terminal of the low-side driver circuit 14 and the bootstrap voltage input terminal of the low-side driver circuit 14, and is connected to the energy storage circuit 12 to access the charging voltage and the bootstrap voltage;

[0086] The negative logic level terminal IN- of the low-side driver and the ground terminal GND of the low-side driver U1 serve as the signal ground of the low-side driver circuit 14; when the first drive signal PWM1 is at a high level, the signal ground is the power supply voltage VAA; when the first drive signal PWM1 is at a high level, the signal ground is the power ground;

[0087] The positive logic level terminal IN+ of the low-side driver U1 is used as the second drive signal input terminal of the low-side drive circuit 14 to receive the second drive signal PWM2;

[0088] The pull-up gate driving terminal OUTH of the low-side driver U1 and the pull-down gate driving terminal OUTL of the low-side driver are used together as the first driving signal output terminal of the low-side driving circuit 14 , and are connected to the switch circuit 11 to output the first driving signal PWM1 .

[0089] The low-side driver U1 can use TI's LMG1020 chip; the minimum driving pulse width of LMG1020 is 1ns, and the typical value of transmission delay is 2.5ns. In this application, the low-side driver LMG1020 can be used as a high-side driver, which can ensure that the driving pulse width of the N-type switch tube is about 5ns, and the N-type switch tube can be turned on and off quickly. In addition, the size of LMG1020 of 0.8mm×1.2mm is very conducive to the miniaturization of the driving circuit, and is very suitable for use in vehicle-mounted laser radar systems.

[0090] The ground terminal GND of the low-side driver is used as the signal ground of the low-side drive circuit 14; when the first drive signal PWM1 is at a high level, the signal ground is the power supply voltage VAA; when the first drive signal PWM1 is at a high level, the signal ground is the power ground; and the power supply terminal VDD of the low-side driver U1 is used as the charging voltage input terminal of the low-side drive circuit 14 and the bootstrap voltage input terminal of the low-side drive circuit 14, and is connected to the energy storage circuit 12 to access the charging voltage and the bootstrap voltage; when the first drive signal PWM1 is at a high level, the low-side driver raises the second drive signal PWM2 to output the first drive signal PWM1, thereby realizing the high-side drive of the N-type switch tube.

[0091] like Figure 6 As shown, the charging circuit 13 includes a second NMOS tube N2;

[0092] The gate of the second NMOS transistor N2 is used as the fourth drive signal input terminal of the charging circuit 13 to receive the fourth drive signal; the drain of the second NMOS transistor N2 is used as the DC power input terminal of the charging circuit 13, connected to the energy storage circuit 12 to receive the DC power supply VBB flowing out of the energy storage circuit 12; the source of the second NMOS transistor N2 is connected to the power ground. The fourth drive signal is inversely proportional to the first drive signal PWM1.

[0093] The second NMOS transistor N2 is used as the charging circuit 13, thereby reducing the energy consumption of the laser driving circuit.

[0094] like Figure 7 As shown, the charging circuit 13 includes a first resistor R1;

[0095] The first end of the first resistor R1 is used as the DC power input end of the charging circuit 13 and is connected to the energy storage circuit 12 to receive the DC power VBB flowing out of the energy storage circuit 12 ; the second end of the first resistor R1 is connected to the power ground.

[0096] The first resistor R1 is used as the charging circuit 13, which simplifies the hardware design of the laser driving circuit.

[0097] like Figure 6As shown, the first level conversion circuit 15 includes a first magnetic element T1; in a specific implementation, the first magnetic element T1 can be a transformer or a common mode inductor.

[0098] The first input end of the first magnetic element T1 is used as the third driving signal input end of the first level conversion circuit 15 to receive the third driving signal PWM3; the second input end of the first magnetic element T1 is connected to the power ground;

[0099] The first output end of the first magnetic element T1 is used as the second driving signal output end of the first level conversion circuit 15 and is connected to the low-side driving circuit 14 to output the second driving signal PWM2;

[0100] The second output end of the first magnetic element T1 serves as the signal ground of the first level conversion circuit 15; when the first drive signal PWM1 is at a high level, the signal ground is the power supply voltage VAA; when the first drive signal PWM1 is at a low level, the signal ground is the power ground or in a floating state.

[0101] like Figure 7 As shown, the first level conversion circuit 15 includes a first photocoupler U2 and a first current limiting resistor Rs1.

[0102] The positive electrode of the first photocoupler U2 is used as the third driving signal input terminal of the first level conversion circuit 15 to receive the third driving signal PWM3; the negative electrode of the first photocoupler U2 is connected to the power ground;

[0103] The emitter of the first photocoupler U2 and the first end of the first current limiting resistor Rs1 serve together as the second drive signal output end of the first level conversion circuit 15 , and are connected to the low-side drive circuit 14 to output the second drive signal PWM2 .

[0104] The second end of the first current limiting resistor Rs1 serves as the signal ground of the first level conversion circuit 15; when the first drive signal PWM1 is at a high level, the signal ground is the power supply voltage VAA; when the first drive signal PWM1 is at a low level, the signal ground is the power ground or in a floating state.

[0105] The collector of the first photocoupler U2 serves as the DC power supply input terminal of the first level conversion circuit 15 and is connected to the unidirectional conduction circuit 17 and the energy storage circuit 12 to receive the unidirectional conduction DC power supply VBB.

[0106] The light source 90 includes a light emitting diode (LED); the positive electrode of the light emitting diode (LED) is used as the power supply voltage input terminal of the light source 90 and is connected to the switch circuit 11 to access the power supply voltage; the negative electrode of the light emitting diode (LED) is connected to the power ground.

[0107] The following is a combination of working principles Figure 6As shown for further explanation:

[0108] The first diode D1 conducts the power supply DC power VBB in a unidirectional manner.

[0109] When the first drive signal PWM1 is at a low level, the first NMOS tube N1 is turned off according to the first drive signal PWM1, the fourth drive signal is at a high level, the second NMOS tube N2 is turned on and conducts the power supply DC power VBB flowing out through the energy storage circuit 12 to the power supply ground; the first capacitor C1 is charged according to the power supply DC power VBB to generate a charging voltage; at this time, the voltage of the first node A is the power supply ground, the first magnetic element T1 isolates the third drive signal PWM3 and outputs the second drive signal PWM2 to the positive logic level terminal IN+ of the low-side driver U1, and the low-side driver U1 converts the second drive signal PWM2 into the first drive signal PWM1 according to the charging voltage and outputs it from the pull-up gate drive terminal OUTH of the low-side driver and the pull-down gate drive terminal OUTL of the low-side driver to the gate of the first NMOS tube N1.

[0110] When the first drive signal PWM1 is at a high level, the first NMOS tube N1 transmits the power supply voltage VAA according to the first drive signal PWM1 to light the light source; the fourth drive signal is at a low level, and the second NMOS tube N2 is turned off; the first capacitor C1 bootstraps the power supply voltage VAA according to the charging voltage to output the bootstrap voltage to the power supply terminal VDD of the low-side driver U1; at this time, the voltage of the first node A is the power supply voltage VAA, and the first magnetic element T1 lifts and isolates the third drive signal PWM3 according to the power supply voltage VAA to output the second drive signal PWM2 to the positive logic level terminal IN+ of the low-side driver U1, and the low-side driver U1 converts the second drive signal PWM2 into the first drive signal PWM1 according to the bootstrap voltage and outputs it from the pull-up gate drive terminal OUTH of the low-side driver and the pull-down gate drive terminal OUTL of the low-side driver to the gate of the first NMOS tube N1.

[0111] The following is a combination of working principles Figure 7 As shown for further explanation:

[0112] The first diode D1 conducts the power supply DC power VBB in a unidirectional manner.

[0113] When the first drive signal PWM1 is at a low level, the first NMOS tube N1 is turned off according to the first drive signal PWM1, and the first resistor R1 conducts the power supply DC power VBB flowing out through the energy storage circuit 12 to the power supply ground; the first capacitor C1 is charged according to the power supply DC power VBB to generate a charging voltage; at this time, the voltage of the first node A is the power supply ground, the first photocoupler U2 and the first current limiting resistor Rs1 isolate the third drive signal PWM3 and output the second drive signal PWM2 to the positive logic level terminal IN+ of the low-side driver U1, and the low-side driver U1 converts the second drive signal PWM2 into the first drive signal PWM1 according to the charging voltage and outputs it from the pull-up gate drive terminal OUTH of the low-side driver and the pull-down gate drive terminal OUTL of the low-side driver to the gate of the first NMOS tube N1.

[0114] When the first drive signal PWM1 is at a high level, the first NMOS tube N1 outputs the power supply voltage VAA to the light source to light up the light source; at this time, the voltage of the first node A is the power supply voltage VAA, and the first capacitor C1 bootstraps the power supply voltage VAA according to the charging voltage to output the bootstrap voltage to the power supply terminal VDD of the low-side driver U1; the first photocoupler U2 and the first current limiting resistor Rs1 lift and isolate the third drive signal PWM3 according to the power supply voltage VAA to output the second drive signal PWM2 to the positive logic level terminal IN+ of the low-side driver U1, and the low-side driver U1 converts the second drive signal PWM2 into the first drive signal PWM1 according to the bootstrap voltage and outputs it from the pull-up gate drive terminal OUTH of the low-side driver and the pull-down gate drive terminal OUTL of the low-side driver to the gate of the first NMOS tube N1.

[0115] Figure 8 A partial exemplary circuit structure of a laser driving circuit provided by an embodiment of the utility model is shown. Fig. 9 Another partial exemplary circuit structure of the laser driving circuit provided by the embodiment of the utility model is shown. For the convenience of description, only the part related to the embodiment of the utility model is shown, which is described in detail as follows:

[0116] exist Figure 8In the embodiment, the second level conversion circuit 18 includes a second magnetic element T2; in a specific implementation, the second magnetic element T2 can be a transformer or a common mode inductor. The first input end of the second magnetic element T2T serves as the fourth drive signal input end of the second level conversion circuit 18 to access the fourth drive signal PWM4; the second input end of the second magnetic element T2 is connected to the power ground; the first output end of the second magnetic element T2 serves as the fifth drive signal output end of the second level conversion circuit 18, and is connected to the low-side drive circuit 14 to output the fifth drive signal PWM5; the second output end of the second magnetic element T2 serves as the signal ground of the second level conversion circuit 18; when the first drive signal PWM1 is at a high level, the signal ground is the power supply voltage VAA; when the first drive signal PWM1 is at a high level, the signal ground is the power ground.

[0117] exist Figure 8 In the embodiment, the negative logic level terminal IN- of the low-side driver is used as the fifth driving signal input terminal of the low-side driving circuit 14 to receive the fifth driving signal PWM5;

[0118] besides, Figure 8 The circuit structure and Figure 6 The circuit structure is the same.

[0119] It should be noted that in Figure 8 In the embodiment, the voltage of the first node A is the power ground, the second magnetic element T2 isolates the fourth drive signal PWM4 and outputs the fifth drive signal PWM5 to the negative logic level terminal IN- of the low-side driver U1, and the low-side driver U1 converts the second drive signal PWM2 and the fifth drive signal PWM5 into the first drive signal PWM1 according to the charging voltage (for example, XOR operation) and outputs it from the pull-up gate drive terminal OUTH of the low-side driver and the pull-down gate drive terminal OUTL of the low-side driver to the gate of the first NMOS tube N1. The voltage of the first node A is the power supply voltage VAA, the second magnetic element T2 lifts and isolates the fourth drive signal PWM4 according to the power supply voltage VAA to output the fifth drive signal PWM5 to the negative logic level terminal IN- of the low-side driver U1, and the low-side driver U1 converts the second drive signal PWM2 and the fifth drive signal PWM5 into the first drive signal PWM1 according to the bootstrap voltage and outputs it from the pull-up gate drive terminal OUTH of the low-side driver and the pull-down gate drive terminal OUTL of the low-side driver to the gate of the first NMOS tube N1. In addition, Figure 8 The circuit working principle and Figure 6 The circuit works on the same principle.

[0120] exist Fig. 9In the embodiment, the second level conversion circuit 18 includes a second photocoupler U3 and a second current limiting resistor Rs2; the positive electrode of the second photocoupler U3 serves as the fourth drive signal input terminal of the second level conversion circuit 18 to access the fourth drive signal PWM4; the negative electrode of the second photocoupler U3 is connected to the power ground; the emitter of the second photocoupler U3 and the first end of the second current limiting resistor Rs2 serve together as the fifth drive signal output terminal of the second level conversion circuit 18, and are connected to the low-side drive circuit 14 to output the fifth drive signal PWM5; the second end of the second current limiting resistor Rs2 serves as the signal ground of the second level conversion circuit 18; when the first drive signal PWM1 is at a high level, the signal ground is the power supply voltage VAA; when the first drive signal PWM1 is at a high level, the signal ground is the power supply ground; the collector of the second photocoupler U3 serves as the power supply DC input terminal of the second level conversion circuit 18, and is connected to the unidirectional conduction circuit 17 and the energy storage circuit 12 to access the unidirectional conduction power supply DC VBB.

[0121] exist Fig. 9 In the embodiment, the negative logic level terminal IN- of the low-side driver is used as the fifth driving signal input terminal of the low-side driving circuit 14 to receive the fifth driving signal PWM5;

[0122] besides, Fig. 9 The circuit structure and Figure 7 The circuit structure is the same.

[0123] It should be noted that the voltage of the first node A is the power ground, the second photocoupler U3 and the second current limiting resistor Rs2 isolate the fourth drive signal PWM4 and output the fifth drive signal PWM5 to the negative logic level terminal IN- of the low-side driver U1, and the low-side driver U1 converts the second drive signal PWM2 and the fifth drive signal PWM5 into the first drive signal PWM1 according to the charging voltage (for example, XOR operation) and outputs it from the pull-up gate drive terminal OUTH of the low-side driver and the pull-down gate drive terminal OUTL of the low-side driver to the gate of the first NMOS tube N1. The voltage of the first node A is the power supply voltage VAA, and the first capacitor C1 bootstraps the power supply voltage VAA according to the charging voltage to output the bootstrap voltage to the power supply terminal VDD of the low-side driver U1; the second photocoupler U3 and the second current limiting resistor Rs2 lift and isolate the fourth drive signal PWM4 according to the power supply voltage VAA to output the fifth drive signal PWM5 to the negative logic level terminal IN- of the low-side driver U1, and the low-side driver U1 converts the second drive signal PWM2 and the fifth drive signal PWM5 according to the bootstrap voltage (for example, XOR operation) into the first drive signal PWM1 and outputs it from the pull-up gate drive terminal OUTH of the low-side driver and the pull-down gate drive terminal OUTL of the low-side driver to the gate of the first NMOS tube N1. In addition, Fig. 9The circuit working principle and Figure 7 The circuit works on the same principle.

[0124] An embodiment of the utility model also provides a laser radar, which includes a light source and the above-mentioned laser driving circuit.

[0125] In the embodiment of the utility model, when the first drive signal is at a low level, the charging circuit conducts the power supply direct current flowing out through the energy storage circuit to the power supply ground so that the energy storage circuit is charged according to the power supply direct current to generate a charging voltage, and when the first drive signal is at a high level, the energy storage circuit bootstraps the power supply voltage according to the charging voltage to output the bootstrap voltage; the low-side drive circuit is connected to the second drive signal, and when the first drive signal is at a high level, the second drive signal is converted into the first drive signal according to the bootstrap voltage so that the switch circuit outputs the power supply voltage to the light source to light the light source, and when the first drive signal is at a low level, the second drive signal is converted into the first drive signal according to the charging voltage; the switch circuit includes an N-type switch tube; when the light source works with a common cathode grounded, the shutdown speed is improved and the circuit volume is reduced.

[0126] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0127] 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 laser driving circuit, characterized in that: include: A switch circuit is configured to output a supply voltage to the light source to light up the light source when the first drive signal is at a high level; the switch circuit includes an N-type switch tube; an energy storage circuit, connected to the switch circuit, configured to be connected to a power supply DC, to be charged according to the power supply DC to generate a charging voltage when the first drive signal is at a low level, and to bootstrap the power supply voltage according to the charging voltage to output a bootstrap voltage when the first drive signal is at a high level; a charging circuit connected to the energy storage circuit and the switch circuit, and configured to conduct the power supply DC current flowing out of the energy storage circuit to a power ground when the first drive signal is at a low level; A low-side drive circuit is connected to the switch circuit, the energy storage circuit and the charging circuit, and is configured to receive a second drive signal, convert the second drive signal into the first drive signal according to the bootstrap voltage when the first drive signal is at a high level, and convert the second drive signal into the first drive signal according to the charging voltage when the first drive signal is at a low level.

2. The laser driving circuit according to claim 1, characterized in that: Also includes: A first level conversion circuit is connected to the switch circuit, the energy storage circuit, the charging circuit and the low-side drive circuit, and is configured to receive a third drive signal. When the first drive signal is at a high level, the third drive signal is raised and isolated according to the supply voltage to output the second drive signal. When the first drive signal is at a low level, the third drive signal is isolated to output the second drive signal.

3. The laser driving circuit according to claim 2, characterized in that: Also includes: a second level conversion circuit, connected to the switch circuit, the energy storage circuit, the charging circuit and the low-side drive circuit, and configured to receive a fourth drive signal, and when the first drive signal is at a high level, to raise and isolate the fourth drive signal according to the supply voltage to output a fifth drive signal, and when the first drive signal is at a low level, to isolate the fourth drive signal to output the fifth drive signal; The low-side drive circuit is specifically configured to convert the second drive signal and the fifth drive signal into the first drive signal according to the bootstrap voltage when the first drive signal is at a high level, and to convert the second drive signal and the fifth drive signal into the first drive signal according to the charging voltage when the first drive signal is at a low level.

4. The laser driving circuit according to claim 2, characterized in that: Also includes: The control circuit is connected to the first level conversion circuit and is configured to provide the third driving signal.

5. The laser driving circuit according to claim 1, characterized in that: Also includes: A unidirectional conduction circuit, connected to the energy storage circuit and the low-side drive circuit, configured to conduct unidirectional conduction of the power supply DC; The energy storage circuit is specifically configured to charge the unidirectionally conducted DC power supply to generate a charging voltage when the first drive signal is at a low level, and to bootstrap the supply voltage according to the charging voltage to output a bootstrap voltage when the first drive signal is at a high level.

6. The laser driving circuit according to any one of claims 1 to 5, characterized in that: The low-side driving circuit comprises a low-side driver; The power supply terminal of the low-side driver serves as a charging voltage input terminal of the low-side driver circuit and a bootstrap voltage input terminal of the low-side driver circuit, and is connected to the energy storage circuit to access the charging voltage and the bootstrap voltage; The negative logic level terminal of the low-side driver and the ground terminal of the low-side driver serve as the signal ground of the low-side driver circuit; when the first drive signal is at a high level, the signal ground is the power supply voltage; when the first drive signal is at a high level, the signal ground is the power ground; The positive logic level terminal of the low-side driver is used as the second drive signal input terminal of the low-side drive circuit to receive the second drive signal; The pull-up gate driving end of the low-side driver and the pull-down gate driving end of the low-side driver serve together as the first driving signal output end of the low-side driving circuit, and are connected to the switch circuit to output the first driving signal.

7. The laser driving circuit according to any one of claims 1 to 5, characterized in that: The N-type switch tube is a first NMOS tube; The gate of the first NMOS transistor serves as the first drive signal input terminal of the switch circuit, and is connected to the low-side drive circuit to receive the first drive signal; the drain of the first NMOS transistor serves as the power supply voltage input terminal of the switch circuit to receive the power supply voltage; The source of the first NMOS tube serves as the power supply voltage output terminal of the switch circuit and is connected to the light source to output the power supply voltage.

8. The laser driving circuit according to any one of claims 1 to 5, characterized in that: The charging circuit includes a second NMOS tube; The gate of the second NMOS tube serves as the fourth drive signal input terminal of the charging circuit to receive the fourth drive signal; the drain of the second NMOS tube serves as the DC power input terminal of the charging circuit and is connected to the energy storage circuit to receive the DC power flowing out of the energy storage circuit; the source of the second NMOS tube is connected to the power ground; The fourth driving signal is in anti-phase with the first driving signal.

9. The laser driving circuit according to any one of claims 1 to 5, characterized in that: The charging circuit includes a first resistor; The first end of the first resistor serves as a DC power supply input end of the charging circuit and is connected to the energy storage circuit to receive the DC power supply flowing out of the energy storage circuit; the second end of the first resistor is connected to a power ground.

10. The laser driving circuit according to any one of claims 2 to 4, characterized in that: The first level conversion circuit includes a first magnetic element; The first input end of the first magnetic element serves as the third driving signal input end of the first level conversion circuit to receive the third driving signal; the second input end of the first magnetic element is connected to the power ground; The first output end of the first magnetic element serves as the second drive signal output end of the first level conversion circuit and is connected to the low-side drive circuit to output the second drive signal; The second output end of the first magnetic element serves as the signal ground of the first level conversion circuit; when the first drive signal is at a high level, the signal ground is the supply voltage; when the first drive signal is at a low level, the signal ground is the power ground or is in a floating state.

11. The laser driving circuit according to any one of claims 2 to 4, characterized in that: The first level conversion circuit includes a first photocoupler and a first current limiting resistor; The positive electrode of the first photocoupler is used as the third driving signal input terminal of the first level conversion circuit to receive the third driving signal; the negative electrode of the first photocoupler is connected to the power ground; The emitter of the first photocoupler and the first end of the first current limiting resistor serve together as the second drive signal output end of the first level conversion circuit, and are connected to the low-side drive circuit to output the second drive signal; The second end of the first current limiting resistor serves as a signal ground of the first level conversion circuit; when the first driving signal is at a high level, the signal ground is the power supply voltage; When the first driving signal is at a low level, the signal ground is a power ground or in a floating state; The collector of the first photoelectric coupler serves as a power supply DC input terminal of the first level conversion circuit and is connected to the energy storage circuit to access the power supply DC.

12. A laser radar, characterized in that: The laser radar comprises a light source and a laser driving circuit as described in any one of claims 1 to 11.

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