1. Introduction The MSP430 series microcontroller is a new generation of 16-bit microcontrollers manufactured by Texas Instruments (TI). It is an ultra-low-power mixed-signal processor with advantages such as low voltage, ultra-low power consumption, powerful processing capabilities, stable system operation, rich on-chip peripherals, and ease of development. It offers high cost-effectiveness and has a wide range of applications in engineering control and other fields. The switching boost regulated power supply utilizes the energy storage characteristics of switching devices, passive magnetic components, and capacitors to obtain separated energy from the input voltage source. This energy is temporarily stored in the form of a magnetic field in an inductor or an electric field in a capacitor, and then converted to the load. A boost chopper circuit is used for the DC-DC main circuit. 2. System Structure and Overall Design Scheme This switching regulated power supply uses the MSP430F449 as the main control device. It is a powerful 16-bit microcontroller manufactured by TI with ultra-low power consumption. Its low power consumption is beneficial for high system efficiency requirements, and its ADC12 is a high-precision 12-bit A/D conversion module with high speed and versatility. Here, the MSP430 is used to complete the PI regulation of voltage feedback; PWM wave generation, reference voltage setting; voltage and current display; overcurrent protection, etc. The system block diagram is shown in Figure 1. 3 Hardware Circuit Design 3.1 DC/DC Conversion Circuit Design The main hardware circuit of the system consists of power supply, rectifier and filter circuit, DC/DC conversion circuit, drive circuit, MSP430 microcontroller, etc. The AC input voltage passes through the rectifier and filter circuit and then through the DC/DC converter. The Boost chopper circuit is used for DC/DC conversion, as shown in Figure 2: According to the working principle of the boost chopper circuit, the energy stored in the inductor L in one cycle is equal to the energy released, that is: In equation (1), I1 is the output current. The magnitude of the energy stored in the inductor is related to the current passing through it and the inductance value. In the actual circuit, the parameters of the inductor are selected based on the switching frequency and input/output voltage requirements. The appropriate inductance value is selected according to the requirements of the actual circuit, and it should be noted that its internal resistance should not be too large to avoid excessive loss and reduced efficiency of the sampling circuit. For the calculation of the capacitor, under the specified ripple voltage limit, its size is mainly selected according to formula (2): In formula (2): C is the value of the capacitor; D1 is the duty cycle; TS is the switching period of the MOSFET; I0 is the load current; V′ is the output voltage ripple. 3.2 Sampling Circuit The sampling circuit is a voltage acquisition and current acquisition circuit, as shown in Figure 3. Among them, P6.0 and P6.1 are the sampling channels of the MSP430 chip, P6.0 is for voltage acquisition and P6.1 is for current acquisition. Voltage acquisition Since the sampling signal needs to be input into the microcontroller MSP430, its internal sampling reference voltage is selected as 2.5 V. Therefore, the input sampling voltage should be limited to below 2.5 V. Considering the safety margin, the input voltage is limited to below 2 V. When the input voltage is 36 V, the sampling voltage is: 12/(12+200)×36=2.04 V, which meets the requirements. Current acquisition is carried out using constantan wire. First, considering efficiency, the constantan wire cannot be too large. Also, the MSP430 reference voltage is 2.5V, and the required constantan wire needs to be custom-made. Considering these factors, the constantan wire resistance is approximately 0.1Ω. 3.3 PWM Drive Circuit Design: The power MOSFET drive has low power; a transistor drive is sufficient. The drive circuit is shown in Figure 4. Since the microcontroller is a low-voltage system, it needs to be isolated from the high-voltage side to ensure safety and prevent voltage backflow from the high-voltage side from burning out the MSP430. Opto-isolation is first achieved using a switching optocoupler, then the transistor drives the MOSFET via the IR2101 drive circuit. The PWM wave generated by the MSP430 passes through the optocoupler and the subsequent IR2101 chip. The PWM wave output at pin 5 of the IR2101 chip is connected to the gate (G) of the MOSFET, enabling it to operate. The IR2101 is specifically designed to drive high-voltage, high-frequency N-channel MOSFETs and IGBTs. It is an 8-pin chip with high and low-side output reference levels. The gate voltage range is 10–20V. 3.4 Protection Circuit Design Overcurrent protection is a power supply load protection function to prevent damage to the power supply and load caused by overload output current, including short circuits at the output terminals. When the current exceeds the limit, the normally closed contact of the relay is used to disconnect for protection. The MSP430 microcontroller controls the opening and closing of the normally open and normally closed relays to achieve the function of automatic circuit recovery. As shown in Figure 5: 4 Software Design The MSP430 microcontroller has multiple clock sources with high, medium and low speeds, which can be flexibly configured for use by various modules and operate in various low-power modes, greatly reducing the power consumption of the control circuit and improving the overall efficiency; the 430F449 has an ADC12 module that can realize 12-bit precision analog-to-digital conversion, a hardware multiplier, and TIMERA and TIMRB timers with PWM output function, so that the entire circuit can complete real-time acquisition of power supply output voltage and current, PI control, and PWM output without any expansion; at the same time, the MSP430F449 has an internal LCD driver module, and the LCD screen can be directly connected to the chip's driver port, making the circuit structure extremely simple. The software in this design is written in C language. The entire program includes several sub-modules: a keyboard control module, an A/D voltage and current acquisition module, a PI control module, and a PWM wave generation module. The software flowchart is shown in Figure 6. Keyboard control and display module: The voltage reference value can be set and the voltage and current can be switched and displayed via the keyboard. The reference voltage is set and displayed via LEDs, and the acquired voltage and current values ​​are displayed on the LCD. A/D voltage and current acquisition module: The 12-bit A/D conversion module of the MSP430 microcontroller acquires the system output voltage and load current. PI control module: This module is used to control the system output voltage to stabilize it. Its control principle is shown in Figure 7. PWM wave generation module: Utilizes the comparison function of the TimerB timer of the MSP430 microcontroller to generate a signal to drive the MOSFET. 5. Experimental Results Analysis Through the software design using the MSP430 microcontroller, by selecting reasonable parameters and switching frequency for PI adjustment, voltage stabilization can be achieved, ensuring that the first three indicators mentioned above achieve good results. Whether ripple voltage can be limited mainly depends on the capacitors in the rectifier filter circuit; therefore, the selection of high-voltage supporting electrolytic capacitors is crucial. After selecting the switching components, efficiency is mainly affected by the switching frequency, the internal resistance of the energy storage inductor, and the losses of other components in the circuit. Therefore, the loss level of the components should be carefully considered during selection. A comprehensive test of this system was conducted, and the results are shown in Table 1. 6 Conclusion This switching power supply design uses the low-power TI 16-bit microcontroller MSP430F449 as the control core. Based on PWM control technology, closed-loop PI regulation, and high-precision 12-bit A/D conversion, it completes the functions and parameter specifications for sampling value display and voltage value setting. Experimental results show that by designing with the MSP430 microcontroller software and selecting reasonable parameters and switching frequency for PI regulation, voltage regulation can be achieved.