A driving circuit for a microchip laser

Abstract

This invention discloses a driving circuit for a microchip laser, comprising: an analog switch circuit controlling the opening and closing of a constant current discharge circuit according to an externally input control signal; the constant current discharge circuit, after being controlled by the analog switch circuit to open, outputting a discharge signal to a voltage converter circuit and outputting electrical energy input from a capacitor energy storage circuit to the outside; the voltage converter circuit increasing the voltage input range, performing voltage conversion on the discharge signal, and outputting the voltage-converted discharge signal to an error amplifier charging current-limiting circuit; the error amplifier charging current-limiting circuit detecting the magnitude of the internal current of the driving circuit and limiting the current, and outputting the current-limited discharge signal to the capacitor energy storage circuit; and the capacitor energy storage circuit storing electrical energy and outputting electrical energy to the constant current discharge circuit according to the current-limited discharge signal. This invention features high charging efficiency, a wide input voltage range, low equivalent resistance of the energy storage capacitor, small size, good adaptability to high and low temperature environments, and no significant reduction in capacity at low temperatures.

Description

Technical Field

[0001] This invention belongs to the field of microchip laser control technology, and specifically relates to a driving circuit for a microchip laser. Background Technology

[0002] Microchip lasers, as a type of semiconductor-pumped solid-state laser, offer advantages such as compact structure, high beam quality, and high conversion efficiency. A microchip laser typically consists of a thin etalon of gain material with a dielectric film coated on its surface and a semiconductor laser serving as the pump source. It generates high-intensity laser output through stimulated emission amplification. Depending on the specific requirements, the driving circuit of the microchip laser modulates its output intensity, frequency, and pulse width by controlling the driving current of the laser diode. This driving circuit features low noise, high precision, and fast response, ensuring the stability and reliability of the laser output.

[0003] Currently, the driving current of microchip laser driving circuits used in China does not exceed 20A under a certain pulse width. The converters are mostly built using imported lithium battery charging chips, and the energy storage capacitors are mostly supercapacitors or electrolytic capacitors. Such technical solutions have many problems such as low charging efficiency, narrow voltage range, large equivalent resistance of capacitors, large size, and poor adaptability to high and low temperature environments. Summary of the Invention

[0004] The purpose of this invention is to provide a driving circuit for a microchip laser, which has high charging efficiency, wide input voltage range, low equivalent resistance of energy storage capacitor, small size, good adaptability to high and low temperature environments, and no significant reduction in capacity at low temperatures.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a driving circuit for a microchip laser, comprising: an analog switching circuit, a constant current discharge circuit, a voltage converter circuit, an error amplifier charging and current limiting circuit, and a capacitor energy storage circuit; wherein,

[0006] Analog switching circuit, used to control the opening and closing of constant current discharge circuit according to externally input control signals;

[0007] The constant current discharge circuit is used to output a discharge signal to the voltage converter circuit after the analog switch circuit controls its turn-on, and to output the electrical energy input to the capacitor energy storage circuit to the outside.

[0008] The voltage converter circuit is used to increase the voltage input range, convert the discharge signal into voltage, and output the converted discharge signal to the error amplifier charging current limiting circuit.

[0009] The error amplifier charging current limiting circuit is used to detect the magnitude of the internal current of the drive circuit and limit the current to protect the drive circuit, and output the discharge signal after current limiting to the capacitor energy storage circuit.

[0010] A capacitor energy storage circuit is used to store electrical energy and output electrical energy to a constant current discharge circuit based on the discharge signal after current limiting.

[0011] The voltage converter circuit uses the SGM61232 chip, which has a voltage input range of 4 to 28V, an internal reference of 0.8V, and a switching frequency of 540Hz.

[0012] The chip model selected for the error amplifier charging current limiting circuit is MS321.

[0013] The capacitor energy storage circuit consists of several identical surface-mount tantalum capacitors connected in parallel, and the selected tantalum capacitor model is CAK55-H-10V-1500uF-K.

[0014] The chip model selected for the constant current discharge circuit is MS358.

[0015] The chip model selected for the analog switch circuit is SGM3157.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] This invention, by setting up a voltage converter circuit and a capacitor energy storage circuit formed by several identical surface-mount tantalum capacitors connected in parallel, enables the driving circuit to have high charging efficiency, a wide input voltage range, low equivalent resistance of the energy storage capacitor, small size, good adaptability to high and low temperature environments, and the capacity will not decrease significantly at low temperatures. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the connection structure according to an embodiment of the present invention;

[0019] Figure 2 This is a circuit diagram of the voltage converter circuit in an embodiment of the present invention;

[0020] Figure 3 This is a circuit diagram of the error amplifier charging current limiting circuit in an embodiment of the present invention;

[0021] Figure 4 This is a circuit diagram of the capacitor energy storage circuit in an embodiment of the present invention;

[0022] Figure 5 This is a circuit diagram of the constant current discharge circuit in an embodiment of the present invention;

[0023] Figure 6 This is a circuit diagram of the analog switching circuit in an embodiment of the present invention;

[0024] Figure 7 This is a schematic diagram of the internal structure of the analog switch circuit in an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0026] The technical solution of this invention is: a driving circuit for a microchip laser, such as... Figure 1 The circuit shown includes: an analog switching circuit, a constant current discharge circuit, a voltage converter circuit, an error amplifier charging and current limiting circuit, and a capacitor energy storage circuit; among which,

[0027] Analog switching circuit, used to control the opening and closing of constant current discharge circuit according to externally input control signals;

[0028] The constant current discharge circuit is used to output a discharge signal to the voltage converter circuit after the analog switch circuit controls its turn-on, and to output the electrical energy input to the capacitor energy storage circuit to the outside.

[0029] The voltage converter circuit is used to increase the voltage input range, convert the discharge signal into voltage, and output the converted discharge signal to the error amplifier charging current limiting circuit.

[0030] The error amplifier charging current limiting circuit is used to detect the magnitude of the internal current of the drive circuit and limit the current to protect the drive circuit, and output the discharge signal after current limiting to the capacitor energy storage circuit.

[0031] A capacitor energy storage circuit is used to store electrical energy and output electrical energy to a constant current discharge circuit based on the discharge signal after current limiting.

[0032] Furthermore, the voltage converter circuit is built around the SGM61232 microchip from Sanbang Microelectronics, and features a voltage input range of 4 to 28V, an internal reference of 0.8V, a switching frequency of 540kHz, and overvoltage and overheat protection. Figure 2In this configuration, pin 2 (VIN) of the chip is the power input. Resistors R2 and R5 form a voltage divider at the EN terminal, enabling the chip. C26 is connected to pin 4 (SS) to set the soft-start time. Capacitor C27 and resistor R9 are connected to pin 6 (COMP) for frequency compensation. Resistors R4 and R8 are connected to the voltage divider feedback VSENSE. The freewheeling diode V4 is connected to pin 8 (SW), outputting through inductor L1. Bootstrap capacitor C2 is connected to pin 1 (BOOT). C24 and C25 are output filter capacitors. Resistors R2 and R5 are appropriately selected to ensure that the voltage at the EN terminal is greater than 1.25V after power-on, enabling the chip. C26 is 0.01uF, setting the soft-start time. Capacitor C27 and resistor R9 perform frequency compensation. Resistors R4 are 43kΩ and R8 are 5.6kΩ. Since VSENSE = 0.8V, according to Ohm's law, the output voltage Vdd = 6.9V. The freewheeling diode V4 is a 3A SO340, the inductor L1 is 100uH, and the bootstrap capacitor C2 is 0.1uF. These parameters, when selected appropriately, provide good transient response to the line and load.

[0033] Furthermore, the error amplifier charging current limiting circuit is built around the Ruimeng Electronics MS321 chip, such as... Figure 3 R3 is a 0.1-ohm sampling resistor. According to the error amplifier formula: Vo = (Rf / R7) * (Vi+ - Vi-), Vo is proportional to the difference between the two voltages. In a series circuit, when Rf = R12 and R6 = R7, the circuit also satisfies the requirement that the DC resistance of the two input terminals to ground be equal. R12 is connected across the input and output terminals, and resistor R10 is grounded. R11 and diode V5 are connected to the output, serving as current limiting and reverse protection. R12 is 7.5kΩ and R6 is 1kΩ, amplifying the signal by 7.5 times. When the current through R3 exceeds 2A, Vo will be greater than 1.5V. Subtracting the 0.7V dropout across R5, VSENSE will be greater than 0.8V, thus achieving the current limiting purpose.

[0034] Furthermore, the capacitor energy storage circuit employs twenty surface-mount tantalum capacitors connected in parallel, such as... Figure 4 C4 to C23 are CAK55-H-10V-1500uF-K tantalum capacitors. They have high capacitance, very low equivalent series resistance, and minimal capacitance change at low temperatures.

[0035] According to the formulas: U = Q / C, Q = I × ΔT, we get...

[0036] I×△T=△U×C

[0037] Where: I—discharge current, which is taken as 30A in this embodiment;

[0038] △T—Discharge time, taken as 3ms in this embodiment;

[0039] △U——Volume drop of energy storage capacitor, taken as 3V in this embodiment (the full voltage of the capacitor is 6.9V);

[0040] Calculate C = 30000uF;

[0041] In this embodiment, 20 1500uF / 10V capacitors are connected in parallel.

[0042] Furthermore, the constant current discharge circuit is built around the Ruimeng Electronics MS358 chip and the Xi'an Xinpai NMOS transistor. For example... Figure 5 The current sampling resistor R33 = 35mΩ. When I = 30A, the voltage V is approximately 1V. Therefore, when Vcon is set to 1V, the laser's drive current can reach 30A. Figure 5 Pin 8 (+Vs) of the chip is connected to the +12V power supply, pin 4 (-Vs) is grounded, pin 3 (+INA) is the positive input terminal connected to resistor R20, pin 2 (-INA) is the reverse feedback terminal connected to capacitor C37 and resistors R27 and R28, and the output terminal 1 (OUTA) is connected to R24; the drain terminal of the MOSFET is connected to the negative terminal of laser V3, the source terminal is connected to the sampling resistor R33, and the gate terminal is connected to the resistor R23; the positive terminal of V3 is connected to the energy storage capacitor Vc.

[0043] Furthermore, the analog switching circuit is built around the SGM3157 microchip from Sanbang Microelectronics, such as... Figure 6 When LAS_con = 1, output pin 4 of N3 is connected to pin 1; when LAS_con = 0, output pin 4 of N3 is connected to pin 3. Figure 7 That is, the Vcon potential is equal to the potential of pin 4 of N3. By setting the potential of pin 1 to 1V through a resistor divider, and grounding pin 3, the constant current circuit is turned on and off. For example... Figure 6 Pin 5 (V+) of the chip is connected to +5V, pin 2 (GND) is grounded, pin 1 (NO) is connected to the voltage divider through resistors R14, R16, and R19, pin 3 (NC) is grounded through resistor R25, pin 6 (IN) is connected to the control terminal LAS_con through resistor R21, and pin 4 (COM) is the selection output.

[0044] Furthermore, a summary table of electronic components is shown in Table 1.

[0045] Table 1

[0046]

[0047]

[0048] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A driving circuit for a microchip laser, characterized in that, include: The circuit includes an analog switching circuit, a constant current discharge circuit, a voltage converter circuit, an error amplifier charging and current limiting circuit, and a capacitor energy storage circuit; among which, Analog switch circuit, used to control the opening and closing of constant current discharge circuit according to externally input control signals; The constant current discharge circuit is used to output a discharge signal to the voltage converter circuit after the analog switch circuit controls its turn-on, and to output the electrical energy input to the capacitor energy storage circuit to the outside. The voltage converter circuit is used to increase the voltage input range, convert the discharge signal into voltage, and output the converted discharge signal to the error amplifier charging current limiting circuit. The error amplifier charging current limiting circuit is used to detect the magnitude of the internal current of the drive circuit and limit the current to protect the drive circuit, and output the discharge signal after current limiting to the capacitor energy storage circuit. A capacitor energy storage circuit is used to store electrical energy and output electrical energy to a constant current discharge circuit according to the discharge signal after current limiting. The capacitor energy storage circuit is formed by several identical surface-mount tantalum capacitors connected in parallel.

2. The driving circuit for a microchip laser according to claim 1, characterized in that, The voltage converter circuit uses the SGM61232 chip, which has a voltage input range of 4 to 28V, an internal reference of 0.8V, and a switching frequency of 540Hz.

3. The driving circuit for a microchip laser according to claim 1, characterized in that, The chip model selected for the error amplifier charging current limiting circuit is MS321.

4. The driving circuit for a microchip laser according to claim 1, characterized in that, The tantalum capacitor model selected is CAK55-H-10V-1500uF-K.

5. The driving circuit for a microchip laser according to claim 1, characterized in that, The chip model selected for the constant current discharge circuit is MS358.

6. The driving circuit for a microchip laser according to claim 1, characterized in that, The chip model selected for the analog switch circuit is SGM3157.

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