The operation of green laser pointer is very easy

The circuit uses a constant current source driver chip HY6340 and high-speed integrated operational amplifier, the MAX4215 simplifies the circuit, to improve the control precision. Practical test of the semiconductor laser power, the results show that the output current is 0 ~ 1.5A, current stability, power can achieve the soft-start slow to shutdown, anti-surge function. Been tested, the digital power to achieve steady-state accuracy of the laser power requirements, improve system dynamic performance, while simplifying the hardware circuit. The median and mean composite filter approach. D / A output signal to adjustment, then adjust the output current. The main program loop part of the continuous detection of LD operating current, operating temperature and transmit power, and displayed to view. The operation of green laser pointer is very easy.
If a fault occurs, the interrupt signal into the microcontroller ports (respectively corresponding overvoltage, overcurrent, sudden power outages), the systems are fast protection of the system call interrupt procedures. The main control functions using interrupts, ensure real-time system response. Finally, when the operator presses the buttons off the device, the system call is slow to close the program to stop working. Impact on the role of system interference signal often has a wide spectrum, and the randomness. The system uses a software method to a digital smoothing filter on the sampled signal by the signal processing to reduce the interference on the useful component. Common digital filtering method has a median filter, mean filter [6]. Median filtering and mean filtering method, construct a composite filtering method, which would be: First, the sample signal sorting, removing the maximum and minimum. Especially the child can not use green laser pointer .
The sequence of the remaining data to calculate the average as the filtering results, so that can filter out the impact of interference to retain the useful signal components. The soft-start and slow shutdown: the system startup or shut down by the start / stop button control, if the judge for the boot. The command of the LD driver chip warm-up work, and then gradually increase the operating current to the set value, a soft-start. If the judgment is off, then gradually reduce the operating current zero, the slow shutdown. Current overload protection: the program to set or determine the upper limit of the current value through the keyboard, CPU control digital potentiometer to adjust the voltage of the laser driver chip PIN21 and detect the current, to ensure the stability of the current flowing through the LD to prevent overcurrent damage of LD. Real-time compare the current settings and sampled values when the actual value is greater than limit, the system starts the movement of current-limiting protection. The selling point of this kind of green laser pointer has been attracting more and more customers.
According to the design of the digital power supply, connect the semiconductor lasers used by the existing laboratory performance testing. Laser warm up for half an hour after boot through software settings to adjust the laser current to 1.5A, the lasers start the system running, the operating current rise steadily to reach 1.5A, the dynamic response time is between 1.5 ~ 2s. System output current of 1.5A, 4 hours of continuous work, each interval of 10 minutes record current test sequence and the corresponding current values in accordance with the time order. The test results data depict the curves shown in Figure 3. The results show that the control current of the system is stable, a small error. Closed after the end of the test laser, the system gradually reduce the output voltage signal, to reduce the laser output power to stop working. The results show that, using the power of the digital control scheme to achieve steady-state laser precision. The biggest selling point of  green laser pointer is the fashionable and attractive appearance.