CN117856033A - Constant current driving circuit, laser pumping source and laser radar - Google Patents
Constant current driving circuit, laser pumping source and laser radar Download PDFInfo
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- CN117856033A CN117856033A CN202211222051.XA CN202211222051A CN117856033A CN 117856033 A CN117856033 A CN 117856033A CN 202211222051 A CN202211222051 A CN 202211222051A CN 117856033 A CN117856033 A CN 117856033A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/14—Arrangements for reducing ripples from DC input or output
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of DC power input into DC power output
- H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
- H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
- H02M3/10—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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Abstract
The application provides a constant current drive circuit, a laser pumping source and a laser radar. Wherein, constant current drive circuit includes: the constant current power supply, the voltage reducing circuit, the first resistor and the negative feedback circuit; the output end of the constant current power supply is connected with the power input end of the voltage reducing circuit, the driving signal output end of the voltage reducing circuit is connected with the first end of the first resistor, the second end of the first resistor is connected with the laser pump generator, the input end of the negative feedback circuit is respectively connected with the first end and the second end, and the output end of the negative feedback circuit is connected with the negative feedback signal input end of the voltage reducing circuit. In the present application, the negative feedback circuit is coupled to two ends of the first resistor, and generates a negative feedback signal by sampling a voltage difference between two ends of the first resistor. The step-down circuit can adjust the output driving signal according to the feedback of the negative feedback signal, so that the driving signal has higher stability, and the stable work of the laser pumping generator is realized.
Description
Technical Field
The application relates to the technical field of circuits, in particular to a constant current driving circuit, a laser pumping source and a laser radar.
Background
In practical application scenes, the laser pump generator has weak bearing capacity on electric impact, and tiny current changes can cause parameter changes, so that the safe use of the laser pump generator is endangered. Therefore, the laser pump generator needs a constant current source to drive, and the constant current source must have high current stability and a small fluctuation coefficient.
How to realize a constant current driving circuit meeting the use requirement of the laser pump generator is a problem to be solved.
Disclosure of Invention
The application provides a constant current drive circuit, laser pumping source and laser radar to realize to the appropriate and better electric current of stability of laser pumping generator output numerical value or voltage, make the stable work of laser pumping generator, thereby guarantee the stability of follow-up light path in the laser radar, improve laser radar's range finding performance.
In a first aspect, the present application provides a constant current drive circuit including: the constant current power supply, the voltage reducing circuit, the first resistor and the negative feedback circuit; the output end of the constant current power supply is connected with the power input end of the voltage reduction circuit, the driving signal output end of the voltage reduction circuit is connected with the first end of the first resistor, the second end of the first resistor is connected with the laser pumping generator, the input end of the negative feedback circuit is respectively connected with the first end and the second end, and the output end of the negative feedback circuit is connected with the negative feedback signal input end of the voltage reduction circuit; the constant-current power supply is used for providing constant-current power supply signals for the voltage reduction circuit; the step-down circuit is used for outputting a driving signal according to the constant-current power supply signal, and the driving signal is used for driving the laser pumping generator; the negative feedback circuit is used for collecting a pressure difference signal between the first end and the second end and outputting a negative feedback signal to the voltage reduction circuit based on the pressure difference signal; and the step-down circuit is also used for adjusting the driving signal based on the negative feedback signal.
In some possible implementations, the negative feedback circuit is a differential amplification circuit.
In some possible embodiments, the constant current driving circuit further includes: a voltage regulating circuit; the output end of the voltage regulating circuit is connected with the input end of the negative feedback circuit; the voltage regulating circuit is used for providing a control signal for the negative feedback circuit; and the negative feedback circuit is also used for generating a negative feedback signal according to the control signal.
In some possible embodiments, the constant current driving circuit further includes: a voltage limiting circuit; the input end of the voltage limiting circuit is connected with the driving signal output end of the voltage reducing circuit, and the output end of the voltage limiting circuit is connected with the negative feedback signal input end of the voltage reducing circuit; the voltage limiting circuit is used for outputting a voltage limiting signal according to the voltage of the driving signal; and the voltage reducing circuit is also used for adjusting the driving signal based on the voltage limiting signal.
In some possible embodiments, the voltage limiting circuit is configured to output a voltage limiting signal according to a voltage of the driving signal, and includes: and the voltage limiting circuit is used for outputting a voltage limiting signal when the voltage of the driving signal is equal to a preset voltage.
In some possible embodiments, the voltage limiting circuit comprises: a switch and a voltage dividing circuit; the input end of the voltage dividing circuit is connected with the driving signal output end of the voltage reducing circuit, the output end of the voltage dividing circuit is connected with the input end of the switch, and the output end of the switch is connected with the negative feedback signal input end of the voltage reducing circuit; the switch is used for connecting the voltage dividing circuit and the voltage reducing circuit when the driving signal is equal to the preset voltage; when the driving signal is smaller than the preset voltage, the voltage dividing circuit and the voltage reducing circuit are disconnected; and the voltage dividing circuit is used for outputting a voltage limiting signal when being communicated with the voltage reducing circuit.
In some possible embodiments, the constant current driving circuit further includes: a second resistor; the third end of the second resistor is connected with the output end of the negative feedback circuit, and the fourth end of the second resistor is connected with the negative feedback signal input end of the voltage reduction circuit; the second resistor is a resistor with a resistance value larger than 10KΩ.
In some possible embodiments, the constant current driving circuit further includes: a filter circuit; the input end of the filter circuit is connected with the driving signal output end of the voltage reduction circuit, and the output end of the filter circuit is connected with the first end; and the filter circuit is used for filtering the driving signal.
In some possible implementations, the step-down circuit includes: a control circuit, an error amplifying circuit and a compensating circuit; the input end of the control circuit is connected with the output ends of the error amplifying circuit and the compensating circuit.
In a second aspect, the present application provides a laser pump source. The laser pumping source includes: the constant current driving circuit and the laser pump generator according to the first aspect, wherein the constant current driving circuit is configured to drive the laser pump generator.
In a third aspect, the present application provides a lidar. The laser radar includes: as the laser pump source of the second aspect, the laser pump source is for emitting pump light.
The technical scheme that this application provided can include following beneficial effect:
in the application, the negative feedback circuit is coupled to two ends of the first resistor, and generates a negative feedback signal by sampling a voltage difference value between the two ends of the first resistor. The step-down circuit adjusts the output driving signal according to the feedback of the negative feedback signal, so that the driving signal outputs proper current or voltage with good stability to the laser pumping generator, thereby enabling the laser pumping generator to work stably, ensuring the stability of a subsequent light path in the laser radar and improving the ranging performance of the laser radar. In addition, the resistance of the first resistor is very small, so that the sampling power consumption is small, and the overall efficiency of the constant current source is high.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
Fig. 1 is a schematic diagram of a structure of a constant current driving circuit in the related art;
fig. 2 is a schematic diagram of a structure of another constant current driving circuit in the related art;
fig. 3 is a schematic structural diagram of a first constant current driving circuit in an embodiment of the present application;
fig. 4 is a schematic structural diagram of a second constant current driving circuit in the embodiment of the present application;
fig. 5 is a schematic structural diagram of a third constant current driving circuit in the embodiment of the present application;
fig. 6 is a schematic structural diagram of a fourth constant current driving circuit in the embodiment of the present application;
fig. 7 is a schematic structural diagram of a fifth constant current driving circuit in the embodiment of the present application;
fig. 8 is a schematic diagram of a structure of a sixth constant current driving circuit in the embodiment of the present application.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system configurations, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
In order to illustrate the technical solutions described in the present application, the following description is made by specific examples.
Pumping is a process that uses light to raise (or "pump") electrons from a lower energy level in an atom or molecule to a higher energy level. A laser pump generator is a device that performs pumping by means of laser light, which causes a laser to emit a laser beam. For example, the laser in the lidar may be a seed laser. The seed laser can emit seed light, and the seed light is amplified by the pump light emitted by the laser pump generator to form a laser beam for laser radar detection.
However, the laser pump generator has weak capability of bearing electric shock, and small current changes can cause parameter changes, so that the safe use of the laser pump generator is endangered. Therefore, the laser pump generator needs a constant current source for driving, and the constant current source needs to have high current stability and small fluctuation coefficient.
In one related art of a constant current source drive circuit, the constant current source drive circuit realizes a constant current source through feedback of a sampling resistor. Fig. 1 is a schematic structural diagram of a constant current driving circuit in the related art, and as shown in fig. 1, a resistor R10 in the constant current driving circuit is a current sampling resistor. The error amplifier U4 is used for controlling the upper end voltage of the resistor R10 to be equal to the voltage I_set1 through the operational amplifier negative feedback principle, namely the voltage across the resistor R10 is constant, so that the current of the resistor R10 is constant. Further, since the diode D3 is connected in series with the transistor Q1 and the resistor R10, when the input voltage V2 in the constant current driving circuit is a large current output by the subsequent laser, the power consumption of the transistor Q1 and the resistor R10 becomes large, so that the power consumption of the constant current source is large, the efficiency is low, and the heat productivity is large. In particular pumping typically requires several amperes of drive current and therefore the efficiency of the constant current drive circuit is low.
In addition, in another related art of the constant current drive circuit, the constant current drive circuit also realizes the constant current source by feedback of the sampling resistor. Fig. 2 is a schematic diagram of another structure of a constant current driving circuit in the related art, as shown in fig. 2, a pin G1 of a control chip U5 is grounded through a resistor R14, connected to an anode of a laser LD through a resistor R13, and connected to a pin G2 of an operational amplifier U6 through a resistor R15. A capacitor C3 is connected between the other end of the resistor R13 and the other end of the resistor R14. The positive input terminal of the operational amplifier U6 is connected to the cathode of the laser LD through a resistor R16. The resistor R16 is far away from one end connected with the operational amplifier U6, and is sequentially connected with a resistor R11 and a resistor R12, and the other end of the resistor R12 is grounded. The working process of the circuit is as follows: the feedback voltage at pin G1 of control chip U5 regulates the voltage output to the positive electrode of capacitor C3. If the voltage across the capacitor C3 decreases, the voltage divided by the resistor R13 and the resistor R14 to the pin G1 of the control chip U5 is smaller than the reference voltage inside the control chip U5, and the control chip U5 increases the output, thereby raising the voltage across the capacitor C3. If the voltage of the capacitor C3 is greater than the set voltage, the control chip U5 reduces the output and reduces the voltage at two ends of the capacitor C3, so that the control chip U5 and the auxiliary circuit form a voltage stabilizing voltage source taking the pin G1 of the control chip U5 as a reference.
As can be seen from the above, in the constant current driving circuit in the related art, the sampling resistor is a resistor R11 and a resistor R12 connected in series, and the voltage on the sampling resistor is directly compared with the preset voltage of the control chip U5, so that it is necessary to select from the high efficiency, high accuracy and maximum output current. If high precision is required, the resistance values of the resistor R11 and the resistor R12 need to be large, which in turn results in a large power loss across the resistor R11 and the resistor R12, and the output current is limited. If a large current is required, the resistance of the resistor R11 and the resistor R12 need to be as small as possible, which results in a small voltage drop across the resistor R11 and the resistor R12, i.e. the voltage at both input terminals of the operational amplifier U6 is close to the ground terminal GND (equal to 0), and the control current accuracy is poor. In addition, the current feedback in the scheme is acquired and regulated by a micro control unit (microcontroller unit, MCU) of a control chip U5, and the response speed and the acquisition speed are limited by the MCU, so that a quick response load change scene can not be realized.
Therefore, how to ensure that the constant current driving circuit meets the requirements of low power consumption, high efficiency, high precision and quick response to load change at the same time, so that the constant current driving circuit can be applied to a laser pump generator is a problem to be solved urgently.
In order to solve the above problems, embodiments of the present application provide a constant current source driving circuit to achieve a constant current driving circuit that meets the use requirements of a laser pump generator.
Fig. 3 is a schematic structural diagram of a first constant current driving circuit in an embodiment of the present application. As shown in fig. 3, the constant current driving circuit 300 may include: a constant current power supply V1, a voltage reducing circuit U1, a first resistor R3, and a negative feedback circuit 301.
The output end of the constant current power supply V1 is connected to the power input end Vin of the voltage reducing circuit U1, the driving signal output end SW of the voltage reducing circuit U1 is connected to a first end (an end of the first resistor near the SW port IN the drawing) of the first resistor R3, a second end (an end opposite to the first end) of the first resistor R3 is connected to the laser pump generator D2, the input ends (IN 1 and IN 2) of the negative feedback circuit 301 are respectively connected to the first end and the second end, and the output end OUT1 of the negative feedback circuit is connected to the negative feedback signal input end FB of the voltage reducing circuit U1.
Further, the constant current power supply V1 is configured to provide a constant current power supply signal for the voltage reduction circuit U1, the voltage reduction circuit U1 is configured to output a driving signal according to the constant current power supply signal, and the driving signal is configured to drive the laser pump generator D2. The negative feedback circuit 301 is configured to collect a differential pressure signal between the first end and the second end, and output a negative feedback signal to the voltage step-down circuit U1 based on the differential pressure signal. The step-down circuit U1 is further configured to adjust the driving signal based on the negative feedback signal.
It will be appreciated that the constant current power supply V1 may generate and output a constant current power supply signal, which may then be input to the voltage step-down circuit U1 from the power supply input Vin of the voltage step-down circuit U1. The voltage-reducing circuit U1 may generate a driving signal according to the input constant current power supply signal, and output from the driving signal output terminal SW of the voltage-reducing circuit U1. The driving signal is input into the laser pumping generator D2 after flowing through the first resistor R3. The two input ends of the negative feedback circuit are respectively connected with the two ends of the first resistor R3, so that two voltage signals of the driving signal at the two ends of the first resistor R3 can be respectively input by the two input ends (IN 1 and IN 2) of the negative feedback circuit 301. The negative feedback circuit 301 may generate a negative feedback signal according to a difference between the two voltage signals, and output the negative feedback signal from the output terminal OUT1 of the negative feedback circuit. The negative feedback signal may then be input to the voltage-reducing circuit U1 through the negative feedback signal input FB of the voltage-reducing circuit U1, so that the voltage-reducing circuit U1 adjusts the driving signal according to the input negative feedback signal.
The constant current power supply V1 may be a Direct Current (DC) voltage source, a DC current source, or the like, and the constant current power supply signal output by the constant current power supply V1 may be a fixed DC voltage, so that the constant current power supply V1 is used for controlling the input of the voltage. The voltage-reducing circuit U1 may reduce the fixed direct-current voltage so that the fixed direct-current voltage is converted into a variable direct-current voltage. That is, the step-down circuit U1 steps down the constant current power supply signal to generate a driving signal that is an adjustable signal, so that the step-down circuit U1 can adjust the laser pump generator D2 to work under different voltages.
The first resistor R3 is located between the voltage-reducing circuit U1 and the laser pump generator D2, and a voltage difference (generated by the driving signal flowing through) between two ends of the first resistor R3 may reflect the voltage of the driving signal. The negative feedback circuit generates a negative feedback signal by sampling the voltage difference value at two ends of the first resistor R3 and inputs the negative feedback signal into the voltage-reducing circuit U1, so that the voltage-reducing circuit U1 can adjust the voltage value of the driving signal according to the voltage information fed back by the output driving signal, and a negative feedback loop is realized.
In the above embodiment, the operation procedure of the constant current driving circuit 300 is as follows: the constant current power supply V1 inputs a constant current power supply signal to the voltage reducing circuit U1, the voltage reducing circuit U1 generates a driving signal according to the constant current power supply signal, and the driving signal is output after passing through the sampling resistor (namely the first resistor R3) so as to drive the laser pumping generator D2 to work. The negative feedback circuit 301 samples the voltage difference between two ends of the sampling resistor, generates a negative feedback signal according to the sampled voltage difference signal, after the negative feedback signal is input into the voltage reduction circuit U1, the voltage reduction circuit U1 controls the fixed direct current voltage to be converted into the variable direct current voltage according to the information of the negative feedback signal to adjust the driving signal, and the adjusted driving signal drives the laser pumping generator D2 to work after passing through the sampling resistor, so that the driving signal is output step by step and stable, and the whole circuit realizes constant current source output.
In some possible embodiments, in order to make the circuit more integrated and compact, a chip may be used to implement the functions of part of the circuit. For example, the voltage-reducing circuit U1 may be a voltage-reducing chip. Preferably, the voltage reducing circuit may be a BUCK chip, so that the voltage of the output driving signal is smaller than the voltage of the constant current power supply signal.
It can be understood that the voltage-reducing chip can reduce the voltage of the input constant-current power supply signal, output a driving signal with a voltage value smaller than that of the constant-current power supply signal, and the voltage value of the driving signal can be regulated according to the negative feedback signal.
In some possible embodiments, the step-down circuit U1 may include: a control circuit, an error amplifying circuit and a compensating circuit; the input end of the control circuit is connected with the output ends of the error amplifying circuit and the compensating circuit. One input end of the error amplifying circuit is connected with the output end of the negative feedback circuit, and the output end of the control circuit (namely the driving signal output end of the voltage reducing circuit) is connected with the first end of the first resistor.
In one embodiment, fig. 4 is a schematic structural diagram of a second constant current driving circuit in an embodiment of the present application. As shown in fig. 4, the step-down circuit U1 has an error amplifier U3 (i.e., an error amplifying circuit) and a controller 303 (i.e., a control circuit). The output terminal OUT1 of the negative feedback circuit may be connected to the negative input terminal FB of the error amplifier U3, and the input terminal Vref of the second preset voltage signal may be connected to the positive input terminal of the error amplifier U3, where the output terminal of the error amplifier U3 is connected to the input terminal of the controller 303.
It will be appreciated that the error amplifier U3 may obtain a signal reflecting the error of the voltage value of the negative feedback signal and the second preset voltage value, and the controller 303 adjusts the driving signal under control of this signal. The controller 303 may generate a required driving signal (may be a DC pulse signal) by using a DC-DC power supply (DC/DC conversion). Specifically, when the controller 303 performs DC/DC conversion, the duty ratio of the original direct current input to the controller may be adjusted by means of pulse width modulation (pulse width modulation, PWM), so as to realize control of the output direct current pulse signals with different effective voltages.
In an embodiment, as shown in fig. 4, the voltage-reducing circuit U1 may further have a compensation circuit composed of a resistor R9 and an inductor C2, and the compensation circuit is input to the voltage-reducing circuit U1 through a compensation signal input terminal Vc. The compensation circuit can compensate the input voltage of the voltage-reducing circuit U1, and the stable operation of the constant current driving circuit is maintained.
In some possible implementations, fig. 5 is a schematic structural diagram of a third constant current driving circuit in an embodiment of the present application. As shown in fig. 5, the negative feedback circuit 301 may be a differential amplifying circuit 401.
It is understood that the differential amplifying circuit 401 amplifies only the input differential mode signal and does not amplify the input common mode signal. The negative feedback circuit 301 adopts the differential amplifying circuit 401, and can amplify the voltage signals at two ends of the first resistor R3, so that the generated negative feedback signal is stronger, and the step-down circuit U1 is more beneficial to adjusting the output driving signal according to the negative feedback signal. In addition, when the negative feedback circuit 301 is the differential amplifying circuit 401, the negative feedback circuit 301 can generate the negative feedback signal under the condition that the resistance value of the first resistor R3 is small, so that the loss generated when the driving signal flows through the first resistor R3 can be reduced, and the efficiency of the constant current driving circuit 300 is improved.
In an embodiment, the differential amplifying circuit 401 may be composed of a differential amplifier U2 and a plurality of external resistors (such as a resistor R4, a resistor R5, a resistor R6, and a resistor R7). The positive input terminal of the differential amplifier U2 is coupled to the input terminal IN1 of the negative feedback circuit 301, the negative input terminal of the differential amplifier U2 is coupled to the input terminal IN2 of the negative feedback circuit 301, and the output terminal of the differential amplifier U2 is coupled to the output terminal OUT1 of the negative feedback circuit 301. Resistor R4 is located between the positive electrode input end and the input end IN1 of differential amplifier U2, resistor R6 is located between the negative electrode input end and the input end IN2 of differential amplifier U2, one end of resistor R5 is grounded, one end of resistor R5 is connected with the positive electrode input end of differential amplifier U2, one end of resistor R7 is connected with the negative electrode input end of differential amplifier U2, and one end is connected with the output end of differential amplifier U2.
It will be appreciated that in the above-described differential amplification circuit 401, the external resistor should have a matched ratio, and cannot be arbitrarily selected. For example, the external resistance should satisfy: R5/r4=r7/R6, wherein R4, R5, R6 and R7 represent the resistance values of the resistor R4, the resistor R5, the resistor R6 and the resistor R7, respectively. The above-described resistance does not cause the differential amplifying circuit 401 to generate a bad common mode error at this ratio.
In some possible embodiments, for convenience in controlling the current value of the driving laser pump generator D2, the current adjustment of the driving signal may also be implemented by a circuit other than the voltage-reducing circuit U1. Then, fig. 6 is a schematic structural diagram of a fourth constant current driving circuit in the embodiment of the present application. As shown in fig. 6, the constant current driving circuit 300 may further include: a voltage regulating circuit. The output of the voltage regulating circuit is connected to the input of the negative feedback circuit 301. Here, the voltage adjusting circuit is configured to provide a control signal to the negative feedback circuit 301; the negative feedback circuit 301 is further configured to generate a negative feedback signal according to the control signal.
It will be appreciated that the voltage regulator circuit may generate and output a control signal that may be directly input to one input (IN 1 or IN 2) of the negative feedback circuit 301 to change the state IN which only the driving signal is input to one input (IN 1 or IN 2) of the negative feedback circuit 301, thereby changing the voltage difference input to the two inputs (IN 1 and IN 2) of the negative feedback circuit 301 to achieve the regulation of the negative feedback signal. The adjusted negative feedback signal is input into the voltage-reducing circuit U1, and the voltage-reducing circuit U1 outputs different driving signals according to different negative feedback signals. In this process, the constant current driving circuit 300 realizes controllable adjustment of the driving signal by setting the voltage adjusting circuit.
It can be seen that the control signal can control the magnitude of the driving signal, and then the control signal can be set according to the current requirement of the laser pump generator D2, which is not specifically limited in the embodiment of the present application.
In one embodiment, as shown in fig. 6, the voltage regulation circuit may include an adjustable dc voltage source i_set. The adjustable dc voltage i_set source may have one end grounded and one end connected to the resistor R5, and connected to the positive input end of the differential amplifier U2 through the resistor R5, so that the output end of the voltage adjusting circuit is connected to the input end of the negative feedback circuit 301. The control signal (with different voltages) output by the adjustable direct current voltage source I_set is input into the positive input end of the differential amplifier U2 after passing through the resistor R5, so that the positive input end of the differential amplifier U2 inputs the driving signal and the control signal at the same time. When the control signal changes (voltage), the control signal drives the input signal of the differential amplifier U2 to change, so as to change the negative feedback signal, and the voltage-reducing circuit U1 readjust the driving signal. This process enables the control signal to adjust the drive signal, i.e. the control signal can adjust the drive current of the laser pump generator D2.
In some possible embodiments, when the constant current driving circuit 300 outputs a constant current, the load current is constant, and the output voltage of the voltage reducing circuit U1 changes following the change of the load. However, since the input voltage of the step-down circuit U1 is limited and the output voltage of the step-down circuit U1 is necessarily smaller than the input voltage, the capability of changing the output voltage of the step-down circuit U1 is limited. For example, the input voltage of the step-down circuit U1 may be 12V, and the output voltage of the step-down circuit U1 may be any voltage less than 12V. When the load of the voltage-reducing circuit U1 is 1Ω, the load current is set to 5A, and the output voltage of the voltage-reducing circuit U1 is equal to 5V; when the load of the step-down circuit U1 is 10Ω, the load current is still set to 5A, and the output voltage of the step-down circuit U1 needs 50V, which is much higher than 12V, which is obviously impossible to achieve. There are some cases such that the output of the voltage-decreasing circuit U1 in the case of a load change cannot realize a constant current. To solve this problem, the constant current driving circuit 300 may further include: a voltage limiting circuit 302. Fig. 7 is a schematic structural diagram of a fifth constant current driving circuit in the embodiment of the present application. As shown in fig. 7, an input terminal of the voltage limiting circuit 302 is connected to a driving signal output terminal SW of the voltage reducing circuit, and an output terminal of the voltage limiting circuit 302 is connected to a negative feedback signal input terminal FB of the voltage reducing circuit. The voltage limiting circuit 302 outputs a voltage limiting signal according to the voltage of the driving signal; the voltage-reducing circuit U1 adjusts the drive signal based on the voltage-limiting signal. The voltage limiting circuit 302 may control the voltage of the driving signal so that the output voltage of the constant current driving circuit 300 remains unchanged. The voltage limiting circuit 302 may implement a voltage limiting function. The voltage limiting function can prevent the drive circuit from being damaged due to overhigh output voltage when the load is opened.
It will be appreciated that the input of the voltage limiting circuit 302 may be connected to the drive signal output SW of the buck circuit, and thus the voltage limiting circuit 302 may also receive the drive signal. The voltage limiting circuit 302 may output a control signal according to the driving signal. The control signal output by the voltage limiting circuit 302 is input to the voltage reducing circuit U1 through the negative feedback signal input terminal FB, so that the voltage reducing circuit U1 adjusts the driving signal to keep the circuit constant.
In an embodiment, the condition that the voltage limiting circuit 302 outputs the driving signal may be that the voltage of the driving signal is equal to a preset voltage, that is, when the voltage of the driving signal is equal to the preset voltage, the driving signal triggers the voltage limiting circuit 302 to output the voltage limiting signal, so that the voltage of the driving signal maintains the current voltage and does not increase any more. Conversely, when the voltage of the driving signal is less than the preset voltage, the voltage limiting circuit 302 disconnects the step-down circuit U1. It can be seen that when the drive signal can be set by the drive circuit 300 to reach the maximum voltage that can be achieved, the voltage limiting circuit 302 starts to operate, and a path from the voltage reducing circuit U1 to the voltage limiting circuit 302 to recycle the voltage reducing circuit U1 is formed, so that the voltage limiting circuit 302 controls the drive signal, thereby preventing the laser pump generator D2 from being damaged due to the excessively high voltage of the drive signal.
In some possible embodiments, the voltage limiting circuit 302 may include: a switch and a voltage divider circuit. The input end of the voltage dividing circuit is connected with the driving signal output end SW of the voltage reducing circuit U1, the output end of the voltage dividing circuit is connected with the input end of the switch, and the output end of the switch is connected with the negative feedback signal input end FB of the voltage reducing circuit U1. The switch of the voltage limiting circuit 302 is used for controlling the on-off of the voltage dividing circuit according to the driving signal, and when the driving signal is equal to the preset voltage, the voltage dividing circuit is communicated with the path of the voltage reducing circuit U1, so that the voltage dividing circuit outputs a voltage limiting signal to the voltage reducing circuit U1; when the driving signal is smaller than the preset voltage, the voltage dividing circuit and the voltage reducing circuit U1 are disconnected.
For example, as shown in fig. 7, the switch may be a diode D1, and the voltage dividing circuit may be a circuit composed of a resistor R1 and a resistor R2. The driving signal output by the voltage-reducing circuit U1 reaches the input end of the voltage-limiting circuit 402 through the port Vout, and then is connected to the anode of the diode D1 through the resistor R2 in the voltage-dividing circuit. When the driving signal is equal to the preset voltage, the diode D1 is conducted in the forward direction, so that the voltage limiting signal is generated by the voltage dividing circuit and is input into the negative feedback signal input end FB of the voltage reducing circuit U1, and the voltage of the driving signal is controlled by the voltage reducing circuit U1 according to the voltage limiting signal, thereby preventing the driving signal from being excessively high and damaging the laser pumping generator D2.
In some possible embodiments, in the process of controlling the driving signal by the constant current driving circuit 300 using the voltage limiting circuit 302, since the resistance value of the first resistor R3 is smaller and the resistance value of the voltage limiting circuit 302 is larger, the control capability of the voltage limiting circuit 302 on the driving signal is weaker, and the constant voltage driving circuit 300 cannot be well controlled to enter the constant voltage mode. In order to solve the above-described problem, fig. 8 is a schematic diagram of a structure of a sixth constant current driving circuit in the embodiment of the present application. As shown in fig. 8, the constant current driving circuit 300 may further include: and a second resistor R8. The third end of the second resistor R8 is connected to the output terminal OUT1 of the negative feedback circuit, and the fourth end (the end opposite to the third end) of the second resistor R8 is connected to the negative feedback signal input terminal FB of the voltage-reducing circuit U1. The resistance of the second resistor R8 needs to be much larger than that of R1 or R2. The second resistor R8 may be a resistor having a resistance value of more than 10kΩ, for example.
It can be understood that the output terminal OUT1 of the negative feedback circuit 301 outputs a negative feedback signal to the negative feedback signal input terminal FB of the voltage-limiting circuit U1, and the output terminal of the voltage-limiting circuit 302 outputs a voltage-limiting signal to the negative feedback signal input terminal FB of the voltage-limiting circuit U1, i.e. the negative feedback signal input terminal FB of the voltage-limiting circuit U1 inputs the voltage-limiting signal and the negative feedback signal simultaneously. When the resistance of the second resistor R8 is far greater than that of the voltage limiting circuit 302, the negative feedback signal input terminal FB of the voltage reducing circuit U1 mainly inputs a voltage limiting signal, which is controlled by the resistance of the voltage limiting circuit 302, so that the output voltage of the constant current driving circuit 300 is maintained unchanged.
In an embodiment, as shown in fig. 8, when the voltage dividing circuit (e.g. consisting of the resistor R1 and the resistor R2) is turned on, the resistance of the second resistor R8 is far greater than that of the resistor R1 and the resistor R2, so that the negative feedback signal input terminal FB of the voltage reducing circuit is mainly controlled by the voltage dividing circuit of the resistor R1 and the resistor R2.
In some possible embodiments, the constant current driving circuit 300 may further include: a filter circuit. The input end of the filter circuit is connected with the driving signal output end SW of the voltage reduction circuit, and the output end of the filter circuit is connected with the first end of the first resistor.
It will be appreciated that the filter circuit is used to filter the drive signal. For example, when the signal output by the voltage reduction circuit U1 is a dc pulse signal, the filtering circuit may filter the dc pulse signal to generate a dc voltage.
In one embodiment, as shown in fig. 8, the filter circuit may be composed of an inductor L1 and a capacitor C1. The input end of the inductor L1 is connected with the driving signal output end SW of the voltage reducing circuit, the output end of the inductor L1 is connected with the first end of the first resistor R3 and one end of the capacitor C1, and the other end of the capacitor C1 is grounded.
Next, referring to the circuit shown in fig. 8, the operation of the constant current drive circuit will be described with a specific example.
The controller 303 in the voltage reducing circuit U1 receives the dc voltage input from the constant current source V1, and reduces the dc voltage to generate a driving signal. The filter circuit composed of the inductor L1 and the capacitor C1 receives the driving signal and filters the driving signal. Then, the driving signal is output after passing through the first resistor R3 to drive the laser pumping generator D2 to operate. The positive input end and the negative input end of the differential amplifier U2 respectively sample the voltage difference of the driving signal passing through the two ends of the first resistor R3. The external resistance around differential amplifier U2 determines the amplification of differential amplifier U2 to the differential voltage, thereby generating a negative feedback signal. The negative feedback signal is input to an error amplifier U3 in the step-down circuit U1. The error amplifier U3 compares the negative feedback signal with a second preset voltage signal, and the obtained result is input to the controller 303. The controller 303 adjusts the output drive voltage according to the result. With this cycle, the constant current driving circuit 300 is realized to supply a constant current to the laser pumping generator D2.
In addition, the adjustable dc voltage source i_set in the constant current driving circuit 300 can increase the current of the driving signal when the voltage is reduced, so as to provide a larger current for the laser pumping generator D2. The diode D1 of the constant current driving circuit 300 is turned on in the forward direction when the driving signal reaches the preset voltage, so that the voltage dividing circuit formed by the resistor R1 and the resistor R2 generates a control signal, and the control signal is input into the error amplifier U3 in the voltage reducing circuit U1. The error amplifier U3 compares the sum of the negative feedback signal and the control signal with a second preset voltage signal, and the obtained result is input to the controller 303. The controller 303 adjusts the output drive voltage according to the result. With this cycle, the constant current driving circuit 300 is realized to supply a constant current to the laser pumping generator D2.
In an embodiment, the negative feedback signal is input to the voltage-reducing circuit U1 through the negative feedback signal input terminal FB of the voltage-reducing circuit U1, and the second preset voltage signal is input to the voltage-reducing circuit U1 through the input terminal Vref of the preset voltage signal. The error amplifier U3 inside the voltage-reducing circuit U1 gradually controls the voltage of the negative feedback signal to be equal to the second preset voltage through a loop formed by the voltage-reducing circuit U1 and the negative feedback circuit 301. Because the differential amplifier U2 and the peripheral resistors (resistor R4, resistor R5, resistor R6 and resistor R7) form the differential amplifying circuit 401 to sample the voltage difference flowing through the first resistor R3 to obtain the negative feedback signal, when the adjustable dc voltage source i_set is constant, the amplification factor of the differential amplifier U2 is constant, and the voltage difference between the two ends of the first resistor R3 is constant. That is, the current flowing through the first resistor R3 is constant, so that the current flowing through the laser pumping generator D2 is constant, and the constant current driving circuit realizes constant current driving of the laser pumping generator D2.
When r5/r4=r7/r6 is configured, i_load= (v_ref-i_set) ×r4/R5/R3, where i_load represents a current flowing through the laser pump generator D2 and v_ref represents a preset voltage input from the input terminal Vref of the preset voltage signal inside the step-down circuit U1. The preset voltage may be determined by the step-down circuit U1 itself, with different devices having different preset voltages. I_set represents the voltage of the adjustable dc voltage i_set. R3, R4, R5, R6 and R7 represent the resistance values of the resistor R3, the resistor R4, the resistor R5, the resistor R6 and the resistor R7 respectively.
According to the above formula, the driving current of the laser pumping generator D2 can be controlled by adjusting the voltage of the adjustable dc voltage i_set, and when i_set is equal to or greater than v_ref, i_load_min=0, i_load_min represents the minimum current flowing through the laser pumping generator D2. The minimum value of I_load_min is zero, which means that when I_set is regulated to be more than or equal to V_ref, the constant current driving circuit and the laser pumping generator D2 can be controlled to be disconnected. When i_set=0, the output current is maximum, i_load_max=v_ref_r4/R5/R3, i_load_max representing the maximum current flowing through the laser pump generator D2. It can be seen that I_load has a value between 0 and V_ref_R4/R5/R3.
The resistor R1, the resistor R2, and the diode D1 may form the voltage limiting circuit 302, so that the voltage at the connection port Vout of the voltage limiting circuit 302 is limited, and a maximum voltage v_out_max= (v_ref+u_d1) = (r1+r2)/R1 at the connection port Vout of the voltage limiting circuit 302 is obtained, where u_d1 represents a voltage difference across the unidirectional diode D1, and v_ref+u_d1 represents a voltage intermediate between the resistor R1 and the resistor R2. V_out_max represents the maximum voltage at which the voltage limiting circuit 302 is connected to the port Vout.
V_out represents the voltage at port Vout. When v_out is less than vout_max, diode D1 is turned off in reverse, i_load= (v_ref-i_set) ×r4/R5/R3.
When v_out is equal to vout_max, D1 is turned on in the forward direction, vout_max= (v_ref+u_d1)/(r1+r2)/R1, and R1 and R2 represent the resistance values of the resistor R1 and the resistor R2, respectively.
As can be seen from the above, the constant current driving circuit 300 makes the voltage of the negative feedback signal equal to the preset voltage through the negative feedback loop. Therefore, when v_out is smaller than v_out_max, the diode D1 is turned off reversely, the voltage dividing circuit formed by the resistor R1 and the resistor R2 cannot act on the negative feedback signal input terminal FB of the voltage reducing circuit U1, and the output is completely controlled by the output voltage of the differential amplifier U2, and the constant current driving circuit 300 maintains constant current output.
When v_out increases to v_out_max, the diode D1 is turned on in the forward direction, and the voltage value of the negative feedback signal input terminal FB is controlled by the output voltage of the voltage dividing circuit formed by the resistor R1 and the resistor R2 and the resistor R8. Since the resistance of the resistor R8 is far greater than that of the resistors R1 and R2, the voltage value of the negative feedback signal input terminal FB is mainly controlled by the voltage dividing circuit formed by the resistor R1 and the resistor R2. The resistors R1 and R2 have fixed resistance values so that the constant current drive circuit 300 keeps the output voltage unchanged, v_out=v_out_max.
Based on the same inventive concept, the embodiments of the present application also provide a laser pumping source, which may include a constant current driving circuit and a laser pumping generator, where the constant current driving circuit is used to drive the laser pumping generator. The specific structure and function of the constant current driving circuit may refer to the constant current driving circuit described in the embodiment corresponding to fig. 1 to 8, and for brevity of the description, the description is omitted here.
Based on the same inventive concept, embodiments of the present application also provide a laser radar that may include a laser pump source for emitting pump light. The specific structure and function of the laser pump source may refer to the constant current driving circuit and the laser pump generator described in the embodiments corresponding to fig. 1 to 8, and for brevity of the description, the description is omitted here.
It will be understood by those skilled in the art that the sequence number of each step in the above embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not limit the implementation process of the embodiment of the present application.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that the technical solutions described in the foregoing embodiments may be modified or some of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.
Claims (11)
1. A constant current drive circuit, characterized by comprising: the constant current power supply, the voltage reducing circuit, the first resistor and the negative feedback circuit; the output end of the constant current power supply is connected with the power input end of the voltage reduction circuit, the driving signal output end of the voltage reduction circuit is connected with the first end of the first resistor, the second end of the first resistor is connected with the laser pumping generator, the input end of the negative feedback circuit is respectively connected with the first end and the second end, and the output end of the negative feedback circuit is connected with the negative feedback signal input end of the voltage reduction circuit;
the constant-current power supply is used for providing constant-current power supply signals for the voltage reduction circuit;
the step-down circuit is used for outputting a driving signal according to the constant-current power supply signal, and the driving signal is used for driving the laser pumping generator;
the negative feedback circuit is used for collecting a pressure difference signal between the first end and the second end and outputting a negative feedback signal to the voltage reduction circuit based on the pressure difference signal;
the step-down circuit is also used for adjusting the driving signal based on the negative feedback signal.
2. The constant current driving circuit according to claim 1, wherein the negative feedback circuit is a differential amplifying circuit.
3. The constant current drive circuit according to claim 1 or 2, characterized in that the constant current drive circuit further comprises: a voltage regulating circuit; the output end of the voltage regulating circuit is connected with the input end of the negative feedback circuit;
the voltage regulating circuit is used for providing a control signal for the negative feedback circuit;
the negative feedback circuit is also used for generating the negative feedback signal according to the control signal.
4. The constant current drive circuit according to claim 1, wherein the constant current drive circuit further comprises: a voltage limiting circuit; the input end of the voltage limiting circuit is connected with the driving signal output end of the voltage reducing circuit, and the output end of the voltage limiting circuit is connected with the negative feedback signal input end of the voltage reducing circuit;
the voltage limiting circuit is used for outputting a voltage limiting signal according to the voltage of the driving signal;
the step-down circuit is also used for adjusting the driving signal based on the voltage limiting signal.
5. The constant current drive circuit according to claim 4, wherein the voltage limiting circuit for outputting a voltage limiting signal according to a voltage of the drive signal, comprises:
the voltage limiting circuit is used for outputting a voltage limiting signal when the voltage of the driving signal is equal to a preset voltage.
6. The constant current drive circuit according to claim 5, wherein the voltage limiting circuit includes: a switch and a voltage dividing circuit; the input end of the voltage dividing circuit is connected with the driving signal output end of the voltage reducing circuit, the output end of the voltage dividing circuit is connected with the input end of the switch, and the output end of the switch is connected with the negative feedback signal input end of the voltage reducing circuit;
the switch is used for communicating the voltage dividing circuit with the voltage reducing circuit when the driving signal is equal to the preset voltage; when the driving signal is smaller than the preset voltage, the voltage dividing circuit and the voltage reducing circuit are disconnected;
the voltage dividing circuit is used for outputting the voltage limiting signal when being communicated with the voltage reducing circuit.
7. The constant current drive circuit according to claim 4 or 5, characterized in that the constant current drive circuit further comprises: a second resistor; the third end of the second resistor is connected with the output end of the negative feedback circuit, and the fourth end of the second resistor is connected with the negative feedback signal input end of the voltage reduction circuit;
the second resistor is a resistor with a resistance value larger than 10KΩ.
8. The constant current drive circuit according to claim 1, wherein the constant current drive circuit further comprises: a filter circuit; the input end of the filter circuit is connected with the driving signal output end of the voltage reduction circuit, and the output end of the filter circuit is connected with the first end;
the filter circuit is used for filtering the driving signal.
9. The constant current drive circuit according to claim 1, wherein the step-down circuit includes: a control circuit, an error amplifying circuit and a compensating circuit; the input end of the control circuit is connected with the output ends of the error amplifying circuit and the compensating circuit.
10. A laser pump source comprising:
the constant current drive circuit and the laser pump generator according to any one of claims 1 to 9, wherein the constant current drive circuit is configured to drive the laser pump generator.
11. A lidar, comprising:
the laser pump source of claim 10 for emitting pump light.
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| CN118117438A (en) * | 2024-04-10 | 2024-05-31 | 寰信驿联(上海)科技有限公司 | A high-reliability high-power semiconductor laser constant current drive circuit structure |
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| CN118117438A (en) * | 2024-04-10 | 2024-05-31 | 寰信驿联(上海)科技有限公司 | A high-reliability high-power semiconductor laser constant current drive circuit structure |
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