Research on DC/DC DC Converter Based on SG3525

**Introduction** With the rapid advancement of power conversion technologies, power MOSFETs have become essential components in various switching converter applications. To support this demand, Silicon General Semiconductor Corporation from the United States introduced the SG3525, a dedicated PWM controller designed for driving N-channel power MOSFETs. The SG3525 is a single-chip integrated circuit that offers excellent performance, comprehensive functionality, and wide application versatility. It is known for its simplicity, reliability, and ease of use. The chip features a push-pull output stage, which significantly enhances its driving capability. Additionally, it includes an undervoltage lockout circuit, a soft start function, a control circuit, PWM latch, overcurrent protection, adjustable frequency, and a maximum duty cycle limit. These features make it ideal for a variety of power management systems. Some key performance characteristics of the SG3525 include: 1) A wide operating voltage range of 8 to 35V, making it suitable for a broad range of applications. 2) An internal reference voltage source of 5.1V ± 1.0%, ensuring stable operation. 3) An on-chip oscillator that can operate between 100 Hz and 400 kHz, providing flexibility in frequency selection. 4) Support for external synchronization of the oscillator, allowing for precise timing control. 5) Adjustable dead time, which helps prevent cross-conduction in power switches and improves system efficiency. The final stage uses a push-pull configuration, enabling faster switching speeds and delivering up to 400mA of sink or source current. 6) An undervoltage lockout circuit that disables the chip when the input voltage drops below 8V, reducing power consumption to less than 2mA. 7) A built-in soft start circuit that gradually increases the output voltage, preventing inrush currents. This is achieved by charging a capacitor connected to pin 8, with the voltage rising linearly from 0V to 2.5V over a period determined by the capacitor value and a constant current source. 8) A PWM latch that eliminates noise and jitter, ensuring clean and reliable pulse signals. The system can only be reset in the next clock cycle, enhancing overall stability. **1. Pulse Width Modulator SG3525 Introduction** **1.1 Block Diagram** The SG3525 is a fixed-frequency PWM controller housed in a standard 16-pin DIP package. Its pin functions are illustrated in Figure 1, while the internal block diagram is shown in Figure 2.

**1.2 Pin Function Description** When the DC power supply Vs is connected to pin 15, it splits into two paths: one is fed into the NOR gate, and the other is used to generate a stable reference voltage. The oscillator pins, 5 and 6, must be connected to an external capacitor (CT) and resistor (RT), respectively. The oscillation frequency is determined by these external components. The oscillator output is split into two signals: one serves as a clock signal for the flip-flop and NOR gates, while the other acts as a sawtooth wave input to the comparator. The non-inverting input of the comparator is connected to the sawtooth wave, while the inverting input receives the output of the error amplifier. The comparator then generates a square wave whose width varies according to the error amplifier's output. This signal is sent to one input of the NOR gate, while the other inputs receive the flip-flop and oscillator signals. The flip-flop outputs are complementary, alternating between high and low levels, and drive the bases of transistors VT1 and VT2. The sawtooth wave ensures a dead time between the two transistors, preventing both from being on simultaneously. Finally, VT1 and VT2 produce PWM signals with a 180° phase difference, making the SG3525 an efficient and robust solution for power conversion applications.

Full Outdoor Digital Signage

Full Outdoor Digital Signage,Full Outdoor Signage,Waterproof Lcd Display,High Brightness Digital Signage

Shenzhen Risingstar Outdoor High Light LCD Co., Ltd , https://www.risingstarlcd.com