Semiconductor laser driving circuit

Abstract

The invention belongs to the field of laser ranging, and particularly relates to a semiconductor laser drive circuit, which is characterized in that in order to adapt to different power supply input characteristics, an input power supply is output to a filter circuit after passing through a voltage stabilizing circuit, and a secondary power supply is output to other unit circuits for use after noise and ripples are filtered by the filter circuit; the booster circuit provides driving voltage required for driving the laser; the numerical control circuit adjusts the amplitude of the driving circuit; the fixed width circuit is used for generating a laser driving signal with stable width; the trigger circuit is used for driving the semiconductor laser to output laser pulses. Compared with the prior art, low-cost, low-power-consumption and modular design is carried out on the semiconductor laser driving circuit in the semiconductor laser range finder, and the functions of obtaining a fixed-width laser driving signal through single-chip microcomputer driving, wide power input range, adjustable transmitting power and stable laser pulse width are achieved.

Description

Technical Field

[0001] The invention belongs to the field of laser ranging, in particular to a semiconductor laser driving circuit. Background Art

[0002] Semiconductor laser rangefinders have the characteristics of small size, light weight, easy use, beautiful appearance, high integration, full functions and high degree of automation. They are mostly used in individual soldiers, light weapons and special operations platforms. They can be handheld or installed on a simple bracket for use.

[0003] The laser driving circuit in the semiconductor rangefinder is the core unit circuit. Its function is to provide a certain amount of energy to the semiconductor laser and limit the laser pulse width, thereby providing a certain peak power to the laser.

[0004] The laser pulse width required by the semiconductor rangefinder is about 50ns. The pulse width determines the peak power of the laser. At the same time, in order to drive the power tube switch, the drive signal needs to have a certain drive current.

[0005] Existing technologies typically use logic devices with high temporal resolution to generate narrow pulse signals. This approach has the disadvantage that the pulse width of the drive signal fluctuates significantly over a wide temperature range, affected by the temperature drift of the clock device, and cannot guarantee a constant width. Furthermore, the logic device's limited driving capability cannot directly drive power transistors, and the circuit cost is very high. Summary of the Invention

[0006] The purpose of the present invention is to provide a semiconductor laser driving circuit to realize low-cost, low-power, modular design of the semiconductor laser driving circuit in a semiconductor laser rangefinder, realize the functions of obtaining a fixed-width laser driving signal driven by a single-chip microcomputer, a wide power input range, adjustable transmission power, and stable laser pulse width.

[0007] The technical solution for achieving the purpose of the present invention is: a semiconductor laser driving circuit, comprising:

[0008] The voltage stabilizing circuit uses a switch chip with a wide power input range to stably step down the input circuit to the voltage required by the unit circuit;

[0009] The filter circuit is a π-type filter circuit including a magnetic bead and a capacitor; it is connected to the output voltage of the voltage regulator circuit and is used to filter out the switching noise, ripple and external power supply interference contained in the secondary power supply;

[0010] A boost circuit, connected to the output voltage of the filter circuit, for boosting the driving voltage of the semiconductor laser;

[0011] The digital control circuit is connected to the boost circuit and adjusts the output level of the I2C signal output by the DA chip through the single-chip microcomputer, so as to regulate the output voltage of the boost circuit;

[0012] The fixed width circuit is connected to the output voltage of the filter circuit, and the monostable trigger is used to output a driving signal with a stable pulse width by receiving the leading edge of the signal output by the microcontroller;

[0013] The trigger circuit is connected to the laser driving voltage of the fixed width circuit and is used to drive the power tube to output a driving pulse current to the laser after receiving the driving signal, thereby driving the laser to output a pulse laser.

[0014] Furthermore, the voltage stabilizing circuit includes: a buck chip N1, a power input VIN, a power ground GND, resistors R1, R2, R3, and capacitors C1, C2, and C3; the power input VIN is connected to the second, third, and fifteenth input terminals of the switching buck chip N1, the power ground GND is connected to the fourth, fifth, and sixth input terminals of the switching buck chip N1, the first end of the resistor R2 is connected to the eighth output terminal of the buck chip N1, the second end of the resistor R2 is connected to the first end of the resistor R3, the second section of the resistor R3 is connected to the GND of the buck chip N1 and to the power ground GND, the capacitor C3 is connected to the two ends of the resistor R3, and a 5V regulated output is achieved by selecting the values of the resistors R2 and R3; the two ends of the capacitor C2 are respectively connected to the first end and the sixteenth end of the buck chip N1.

[0015] Furthermore, the filter circuit includes: a magnetic bead B1, and electrolytic capacitors C4 and C5; first ends of the electrolytic capacitors C4 and C5 are respectively connected to two ends of the magnetic bead B1, and second ends of the electrolytic capacitors C4 and C5 are both connected to the power ground GND.

[0016] The semiconductor laser driving circuit according to claim 1 is characterized in that the boost circuit comprises: a boost chip U1, an inductor L1, a rectifier diode V1, capacitors C6, C7, C8, and resistors R4, R5, R6, R7, R8, and R9; the fifth input terminal of the boost chip U1 is connected to the filtered power supply 5V, the two ends of the inductor L1 are respectively connected to the fifth input terminal and the first output terminal of the boost chip U1, the first output terminal of the boost chip U1 is connected to the anode of the rectifier diode V1, the cathode of the rectifier diode V1 is connected to the first end of the resistor R4, the second end of the resistor R4 is connected to the first end of the resistor R5, the first end of the resistor R6, and the third input terminal feedback F of the boost chip U1. B, the second end of the resistor R5 is connected to the power ground GND; the second end of the resistor R6 is connected to the first output end of the DA chip U2, the cathode of the rectifier diode V1 is connected to the first end of the resistor R7, the second end of the resistor R7 is connected to the first end of the resistor R9, and the second end of the resistor R9 is connected to the laser driving voltage HV; the first end of C6 is connected to the cathode of V1, and the second end of C6 is connected to the third end of U1, which is used to reduce the ripple of the output high voltage, the first end of C7 is connected to the first end of R9, the second end of C7 is connected to GND, the first end of C8 is connected to the second end of R9, and the second end of C8 is connected to GND. The RC circuit composed of C7, C8, and R9 reduces the ringing and damped oscillation of the output high voltage.

[0017] Furthermore, the amplitude of the laser driving voltage HV should be consistent with the cathode voltage amplitude of the rectifier diode V1. The calculation formula of HV is:

[0018]

[0019] In the formula, by adjusting V DA The amplitude of HV is adjusted to adjust the peak power of the semiconductor laser.

[0020] Furthermore, the digital control circuit is a unit circuit for adjusting the output level of the DA chip through the I2C signal output by the single chip microcomputer, and is used to adjust the laser power; specifically, it includes: DA chip U2, capacitors C9, C10;

[0021] The external I2C signal is connected to the fifth and sixth input terminals of the DA chip U2 to adjust the amplitude V of the first output terminal of the DA chip U2. DA ; The first ends of capacitors C9 and C10 are connected to +5V, and the second ends of capacitors C9 and C10 are connected to GND, which are used for U2 power input filtering.

[0022] Furthermore, the fixed width circuit includes: a monostable trigger chip U3, a resistor R10, and a capacitor C11;

[0023] The first input terminal of the monostable trigger chip U3 is connected to the external trigger signal, the second, third, and eighth input terminals of the monostable trigger chip U3 are connected to the filtered power supply 5V, the first end of the resistor R10 is connected to the power supply 5V, the second end of the resistor R10 is connected to the seventh input terminal of the monostable trigger chip U3, and the two ends of the capacitor C11 are respectively connected to the seventh and sixth input terminals of the monostable trigger chip U3.

[0024] Furthermore, the trigger circuit includes: a power driving MOS transistor Q1, a diode V2 and a laser H1; the power driving MOS transistor Q1 is selected from BSS138, the gate of the power driving MOS transistor Q1 is connected to the fifth output terminal of the monostable trigger chip U3, the drain of the power driving MOS transistor Q1 is connected to the laser driving voltage HV, the source of the power driving MOS transistor Q1 is connected to the anode of the laser H1, the cathode of the laser H1 is grounded, the anode of the diode V2 is connected to the cathode of the laser H1, and the cathode of the diode V2 is connected to the anode of the laser H1.

[0025] Compared with the prior art, the present invention has the following significant advantages:

[0026] (1) Through the design of a voltage stabilization circuit, a switch chip with a wide power input range (6V to 36V) is used to stably step down the input circuit to the 5V voltage required by the unit circuit;

[0027] (2) Through the design of digital control circuits, a low-cost driving circuit with adjustable laser emission power and stable pulse width can be realized by using only a single-chip microcomputer at the front end, which is universal in the field of semiconductor laser ranging;

[0028] (3) By adding a monostable trigger circuit, a driving signal with a stable pulse width and sufficient driving capability can be constructed to directly drive the power tube to provide a stable operating current for the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the principle block diagram of the semiconductor laser driving circuit;

[0030] Figure 2 This is the schematic diagram of the semiconductor laser driving circuit;

[0031] Figure 3 This is the schematic diagram of the voltage stabilizing circuit and the filtering circuit;

[0032] Figure 4 It is the boost circuit and CNC schematic diagram;

[0033] Figure 5 This is the schematic diagram of the fixed-width circuit and the driving circuit. DETAILED DESCRIPTION

[0034] The terms used in the present invention are only for the purpose of illustrating the embodiments of the present invention and are not intended to limit the present invention. Figure 1-5 , some embodiments of the present invention are described in detail.

[0035] The invention discloses a semiconductor laser driving circuit, which mainly comprises a voltage stabilizing circuit, a filtering circuit, a voltage boosting circuit, a digital control circuit, a width-fixing circuit and a driving circuit.

[0036] In order to adapt to different power input characteristics, the present invention outputs the input power to the filter circuit after passing through the voltage stabilizing circuit. The filter circuit filters out noise and ripples and then outputs the secondary power to other unit circuits for use; the boost circuit provides the driving voltage required for laser driving; the digital control circuit adjusts the amplitude of the driving circuit; the fixed-width circuit is used to generate a laser driving signal with a stable width; and the trigger circuit is used to drive the semiconductor laser to output laser pulses.

[0037] Among them, this circuit is connected to the external circuit through XS1;

[0038] The voltage stabilization circuit uses a switching chip with a wide power input range to stably step down the input circuit to the 5V voltage required by the unit circuit. It specifically includes: step-down chip N1, power input VIN, power ground GND, resistors R1, R2, R3, and capacitors C1, C2, and C3.

[0039] like Figure 3 As shown, the switching buck chip N1 uses XC98321, the power input VIN is connected to the second, third and fifteenth input terminals of the switching buck chip N1, the power ground GND is connected to the fourth, fifth and sixth input terminals of the switching buck chip N1, the first end of the resistor R1 is connected to the fourteenth terminal of the buck chip N1, and the second section of the resistor R1 is connected to GND. The value of the resistor R1 determines the operating frequency of the buck chip N1. The first end of the resistor R2 is connected to the eighth output terminal of the buck chip N1, the second end of the resistor R2 is connected to the first end of the resistor R3, and the second section of the resistor R3 is connected to the GND of the buck chip N1 and the power ground GND. The capacitor C3 is connected to both ends of the resistor R3. By selecting the values of the resistors R2 and R3, a 5V regulated output is achieved; the two ends of the capacitor C2 are respectively connected to the first and sixteenth terminals of the buck chip N1 to achieve soft start of the N1 chip and reduce the power consumption of the circuit startup.

[0040] The filter circuit is a π-type filter circuit, which is used to filter out the switching noise, ripple and external power supply interference contained in the secondary power supply 5V; specifically, it includes: magnetic bead B1, electrolytic capacitors C4 and C5;

[0041] The first ends of the electrolytic capacitors C4 and C5 are connected to the two ends of the magnetic bead B1 respectively, and the second ends of the electrolytic capacitors C4 and C5 are connected to the power ground GND;

[0042] like Figure 3 As shown, one end of the magnetic bead B1 is connected to the eighth output terminal of the switching buck chip N1, and the other end outputs the filtered secondary power supply 5V.

[0043] The boost circuit is a boost type boost circuit used to boost the operating voltage of the laser. The voltage determines the output power of the laser. It specifically includes: boost chip U1, inductor L1, rectifier diode V1, capacitors C6, C7, C8, and resistors R4, R5, R6, R7, R8, and R9.

[0044] The boost chip U1 uses LT1930, which works when the external enable signal EN is high, and is in low-power standby mode at other times;

[0045] like Figure 4 As shown, the fifth input terminal of the boost chip U1 is connected to the filtered power supply 5V, the two ends of the inductor L1 are respectively connected to the fifth input terminal and the first output terminal of the boost chip U1, the first output terminal of the boost chip U1 is connected to the anode of the rectifier diode V1, the cathode of the rectifier diode V1 is connected to the first end of the resistor R4, the second end of the resistor R4 is connected to the first end of the resistor R5, the first end of the resistor R6 and the third input terminal feedback FB of the boost chip U1, the second end of the resistor R5 is connected to the power ground GND; the second end of the resistor R6 is connected to the first end of the DA chip U2 At the output end, the cathode of the rectifier diode V1 is connected to the first end of the resistor R7, the second end of the resistor R7 is connected to the first end of the resistor R9, and the second end of the resistor R9 is connected to the laser driving voltage HV; the first end of C6 is connected to the cathode of V1, and the second end of C6 is connected to the third end of U1, which is used to reduce the ripple of the output high voltage, the first end of C7 is connected to the first end of R9, the second end of C7 is connected to GND, the first end of C8 is connected to the second end of R9, and the second end of C8 is connected to GND. The RC circuit composed of C7, C8, and R9 reduces the ringing and damped oscillation of the output high voltage.

[0046] Among them, the amplitude of the laser driving voltage HV should be consistent with the amplitude of the cathode voltage of the rectifier diode V1, so HV should be obtained by the following formula:

[0047]

[0048] From the above formula, it can be seen that by adjusting the amplitude of VDA, the amplitude of HV can be adjusted, thereby adjusting the peak power of the semiconductor laser;

[0049] The digital control circuit is a unit circuit that adjusts the output level of the DA chip through the I2C signal output by the single-chip microcomputer and is used to adjust the laser power. It specifically includes: DA chip U2, capacitors C9 and C10;

[0050] like Figure 4As shown, the DA chip U2 uses SC7512, and the external I2C signal is connected to the fifth and sixth input terminals of the DA chip U2 to adjust the amplitude VDA of the first output terminal of the DA chip U2; the first terminals of the capacitors C9 and C10 are connected to +5V, and the second terminals of the capacitors C9 and C10 are connected to GND for U2 power input filtering.

[0051] The fixed width circuit is a monostable trigger that receives the leading edge of the signal output by the microcontroller and is used to output a driving signal with a stable pulse width. Specifically, it includes: a monostable trigger chip U3, a resistor R10, and a capacitor C11.

[0052] A first input terminal of the monostable trigger chip U3 is connected to an external trigger signal, and second, third, and eighth input terminals of the monostable trigger chip U3 are connected to a filtered 5V power supply. A first end of a resistor R10 is connected to the 5V power supply, and a second end of the resistor R10 is connected to the seventh input terminal of the monostable trigger chip U3. Two ends of a capacitor C11 are connected to the seventh and sixth input terminals of the monostable trigger chip U3, respectively.

[0053] like Figure 5 As shown, the fixed-width circuit monostable trigger U3 uses 74HVC1G123, and the external trigger signal is connected to the first input terminal of the monostable trigger chip U3. By adjusting the selected values of resistor R10 and capacitor C11, a drive signal with a fixed pulse width can be output from the fifth output terminal of the chip; the first terminals of capacitors C12 and C13 are connected to +5V, and the second terminals of capacitors C12 and C13 are connected to GND, which are used for U3 power input filtering.

[0054] The trigger circuit is a power circuit for driving the laser to output pulsed laser after receiving the driving signal; specifically, it includes: power driving MOS tube Q1, diode V2 and laser H1;

[0055] like Figure 5 As shown, the power driving MOS tube Q1 uses BSS138, the gate of the power driving MOS tube Q1 is connected to the fifth output terminal of the monostable trigger chip U3, the drain of the power driving MOS tube Q1 is connected to the laser driving voltage HV, the source of the power driving MOS tube Q1 is connected to the anode of the laser H1, the cathode of the laser H1 is grounded, the anode of the diode V2 is connected to the cathode of the laser H1, and the cathode of the diode V2 is connected to the anode of the laser H1.

[0056] The conduction time of MOS tube Q1 is driven according to the time width of the driving signal, thereby driving the laser to emit laser pulses. Diode V2 uses MMDL301 to reduce damped oscillation.

[0057] The present invention relates to a semiconductor laser driving circuit, the working principle of which is as follows: an external power supply of 6V to 36V is input to a voltage stabilizing circuit to form a +5V power supply for use by other unit circuits; the output voltage of the boost circuit can be adjusted from 5V to 40V, and its output is controlled by an external I 2 The C signal controls the digital control circuit, and the output voltage of the boost circuit is transmitted to the drain of the power tube Q1. The fixed-width circuit provides a driving signal to the gate of the power tube Q1, thereby providing a driving current for the laser H1.

[0058] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A semiconductor laser driving circuit comprising: The voltage stabilizing circuit uses a switch chip with a wide power input range to stably step down the input circuit to the voltage required by the unit circuit; The filter circuit is a π-type filter circuit including a magnetic bead and a capacitor; it is connected to the output voltage of the voltage regulator circuit and is used to filter out the switching noise, ripple and external power supply interference contained in the secondary power supply; A boost circuit, connected to the output voltage of the filter circuit, for boosting the driving voltage of the semiconductor laser; The digital control circuit is connected to the boost circuit and adjusts the output level of the I2C signal output by the DA chip through the single-chip microcomputer, so as to regulate the output voltage of the boost circuit; The fixed width circuit is connected to the output voltage of the filter circuit, and the monostable trigger is used to output a driving signal with a stable pulse width by receiving the leading edge of the signal output by the microcontroller; The trigger circuit is connected to the laser driving voltage of the fixed width circuit and is used to drive the power tube to output a driving pulse current to the laser after receiving the driving signal, thereby driving the laser to output a pulse laser.

2. The semiconductor laser driving circuit according to claim 1, wherein: The voltage stabilizing circuit includes: a buck chip N1, a power input VIN, a power ground GND, resistors R1, R2, R3, and capacitors C1, C2, and C3; the power input VIN is connected to the second, third, and fifteenth input terminals of the switching buck chip N1, the power ground GND is connected to the fourth, fifth, and sixth input terminals of the switching buck chip N1, the first end of the resistor R2 is connected to the eighth output terminal of the buck chip N1, the second end of the resistor R2 is connected to the first end of the resistor R3, the second section of the resistor R3 is connected to the GND of the buck chip N1 and to the power ground GND, the capacitor C3 is connected to the two ends of the resistor R3, and a 5V regulated output is achieved by selecting the values of the resistors R2 and R3; the two ends of the capacitor C2 are respectively connected to the first end and the sixteenth end of the buck chip N1.

3. The semiconductor laser driving circuit according to claim 1, wherein: The filter circuit includes: a magnetic bead B1, and electrolytic capacitors C4 and C5; first ends of the electrolytic capacitors C4 and C5 are respectively connected to two ends of the magnetic bead B1, and second ends of the electrolytic capacitors C4 and C5 are both connected to the power ground GND.

4. The semiconductor laser driving circuit according to claim 1, wherein: The boost circuit includes: a boost chip U1, an inductor L1, a rectifier diode V1, capacitors C6, C7, C8, and resistors R4, R5, R6, R7, R8, and R9; the fifth input terminal of the boost chip U1 is connected to the filtered power supply 5V, the two ends of the inductor L1 are respectively connected to the fifth input terminal and the first output terminal of the boost chip U1, the first output terminal of the boost chip U1 is connected to the anode of the rectifier diode V1, the cathode of the rectifier diode V1 is connected to the first end of the resistor R4, the second end of the resistor R4 is connected to the first end of the resistor R5, the first end of the resistor R6, and the third input terminal feedback FB of the boost chip U1, and the second end of the resistor R5 is connected To the power ground GND; the second end of the resistor R6 is connected to the first output end of the DA chip U2, the cathode of the rectifier diode V1 is connected to the first end of the resistor R7, the second end of the resistor R7 is connected to the first end of the resistor R9, and the second end of the resistor R9 is connected to the laser driving voltage HV; the first end of C6 is connected to the cathode of V1, and the second end of C6 is connected to the third end of U1, which is used to reduce the ripple of the output high voltage, the first end of C7 is connected to the first end of R9, the second end of C7 is connected to GND, the first end of C8 is connected to the second end of R9, and the second end of C8 is connected to GND. The RC circuit composed of C7, C8, and R9 reduces the ringing and damped oscillation of the output high voltage.

5. The semiconductor laser driving circuit according to claim 4, wherein: The amplitude of the laser driving voltage HV should be consistent with the cathode voltage amplitude of the rectifier diode V1. The calculation formula of HV is: In the formula, by adjusting V DA The amplitude of HV is adjusted to adjust the peak power of the semiconductor laser.

6. The semiconductor laser driving circuit according to claim 4, wherein: The digital control circuit is a unit circuit that adjusts the output level of the DA chip through the I2C signal output by the single-chip microcomputer and is used to adjust the laser power. It specifically includes: DA chip U2, capacitors C9 and C10; The external I2C signal is connected to the fifth and sixth input terminals of the DA chip U2 to adjust the amplitude V of the first output terminal of the DA chip U2. DA ; The first ends of capacitors C9 and C10 are connected to +5V, and the second ends of capacitors C9 and C10 are connected to GND, which are used for U2 power input filtering.

7. The semiconductor laser driving circuit according to claim 1, wherein: The fixed width circuit includes: a monostable trigger chip U3, a resistor R10, and a capacitor C11; The first input terminal of the monostable trigger chip U3 is connected to the external trigger signal, the second, third, and eighth input terminals of the monostable trigger chip U3 are connected to the filtered power supply 5V, the first end of the resistor R10 is connected to the power supply 5V, the second end of the resistor R10 is connected to the seventh input terminal of the monostable trigger chip U3, and the two ends of the capacitor C11 are respectively connected to the seventh and sixth input terminals of the monostable trigger chip U3.

8. The semiconductor laser driving circuit according to claim 1, wherein: The trigger circuit includes: a power driving MOS tube Q1, a diode V2 and a laser H1; the power driving MOS tube Q1 uses BSS138, the gate of the power driving MOS tube Q1 is connected to the fifth output terminal of the monostable trigger chip U3, the drain of the power driving MOS tube Q1 is connected to the laser driving voltage HV, the source of the power driving MOS tube Q1 is connected to the anode of the laser H1, the cathode of the laser H1 is grounded, the anode of the diode V2 is connected to the cathode of the laser H1, and the cathode of the diode V2 is connected to the anode of the laser H1.

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