了解線性穩壓器的優缺點

　　設計者很清楚切換DC/DC變換器的效率，但線性調節器仍然是許多應用的最佳選擇。理解原因將有助于確保設計者做出正確的選擇并正確地執行它。

　　本文比較線性和開關穩壓器，并顯示如何簡單，低成本和穩定性等因素也必須給予適當考慮，連同效率。

　　開關穩壓器：高效但復雜

　　開關穩壓器是高效的，能夠升壓（升壓），降壓（降壓），并輕松地反轉電壓。現代模塊芯片是緊湊，可靠，可從多個供應商。盡管有許多優點，開關調節器也有一些弱點（表1）。

　　Table 1： Comparison of the characteristics of switching and linear regulators. （Table source： Maxim Integrated）

　　First， they are complex chips， and consequently， it can take additional design effort to get a new product working properly. Second， the level of integration of contemporary switching regulators can be expensive， and also increases the chip size. Finally， all that high-frequency switching tends to be noisy.

　　Voltage and current ripple at the input and output filters generated by high-frequency operation can be a major issue for a design using a switching regulator. While these problems can be tackled， it takes time and design skill to do so.

　　Linear regulators address all the key weaknesses of the switching type. They are simple， low cost， require fewer external components， and there is no switching to generate excess noise. In the right application， these modest devices can be a good choice， as shown in Table 1.