With the rapid development of the Internet and communication infrastructure, digital control technology is becoming increasingly popular in telecom, networking, and computer power systems. This is due to its flexibility, reduced component count, advanced control algorithms, improved system communication, and greater immunity to external noise and parameter variations. Digital power is widely used in high-end applications such as servers, storage systems, and telecommunications, where isolation requirements are often necessary.
One of the main challenges in digital power systems is the need to transmit digital or analog signals across isolated boundaries quickly and accurately within a compact space. Traditional optocoupler solutions suffer from limitations such as low bandwidth and significant variation in current transfer ratio (CTR) with temperature and time. Transformer-based solutions, on the other hand, tend to be bulky and prone to magnetic saturation. These issues restrict their use in high-reliability, compact, and long-life applications. This article explores how Analog Devices’ iCoupler® digital isolation technology can effectively address these challenges in digital power supply design.
Isolation is crucial in power supply design to meet safety standards and protect operators from electric shocks and harmful energy. Various global organizations, including VDE, IEC, and UL, specify different insulation requirements based on input and output voltage levels under both steady-state and transient conditions. For example, UL60950 outlines five types of insulation: functional, basic, supplemental, double, and reinforced. Each serves a specific purpose in ensuring electrical safety.
In terms of control strategies, digital power supplies can be categorized into primary-side and secondary-side control. Table 1 compares the functions of both approaches, highlighting features like undervoltage protection (UVP) and overvoltage protection (OVP). The ADP1051, a high-performance digital power controller from Analog Devices, is commonly used for secondary-side control due to its ease of communication with the system. However, it requires an auxiliary power supply during startup, and the PWM signal must cross the isolation boundary. Three common solutions for this include gate drive transformers, digital isolators, and isolated gate drivers.
Gate drive transformers offer advantages such as low latency and cost but require careful design to avoid saturation. Digital isolators, like the ADuM3210, provide a more compact and reliable solution without duty cycle restrictions or saturation issues. Isolated gate drivers, such as the ADuM7223, further simplify the design by integrating isolation and robust gate drive capabilities.
For primary-side control, which is often used in low-cost applications, linear optocouplers, standard optocouplers with amplifiers, and isolated amplifiers are viable options. While optocouplers have limitations in CTR stability, combining them with amplifiers can improve output voltage accuracy. Isolated amplifiers, like the ADuM3190, offer higher bandwidth and accuracy, making them ideal for primary-side control applications.
In conclusion, as telecom, networking, and computer power systems demand higher security, reliability, and efficiency, isolation technology is becoming essential. Analog Devices' iCoupler products, when combined with digital power controllers like the ADP1051, provide reliable, high-bandwidth, and high-density solutions that outperform traditional optocouplers and transformers.
**Reference Circuit**
1. Baoxing Chen. “Micro-transformer isolation is beneficial for digital control.†Power Electronics Technology, October 2008.
2. ADP1051 data sheet. Analog Devices, 2014.
**Author**
Jason Duan
Jason Duan earned his bachelor's and master's degrees in electrical engineering from Xi'an Jiaotong University in 2000 and 2003, respectively. He joined Analog Devices’ power management division in Shanghai in 2007 and moved to the San Jose office in 2013 as a senior application engineer. His current focus includes power electronics, particularly in the development of advanced digital power controllers, ultra-low noise linear regulators, and multi-channel PMU products.
Alumina Ceramic,Alumina Ceramic Ring,99 Alumina Ceramic Ring,Corrosion Resistance Of Alumina Ceramic Ring
Yixing Guanming Special Ceramic Technology Co., Ltd , https://www.guanmingceramic.com