無(wú)光反激拓?fù)浜?jiǎn)化了隔離DC/DC變換器的設(shè)計(jì)

　　除了被用在電信和數(shù)據(jù)通信系統(tǒng)中，直流輸出也在許多其他噪聲敏感的應(yīng)用如汽車蓄電池的充電要求，中間總線電壓為各種電子負(fù)載，和工業(yè)品。雖然反激拓?fù)涫橇餍械母綦xDC / DC轉(zhuǎn)換器應(yīng)用，由于它相對(duì)簡(jiǎn)單和成本較低的替代孤立的拓?fù)浣Y(jié)構(gòu)，設(shè)計(jì)傳統(tǒng)的反激式是不容易的，因?yàn)樽儔浩餍枰脑O(shè)計(jì)，環(huán)補(bǔ)償可以是復(fù)雜的。此外，它需要一個(gè)光耦或額外的變壓器繞組反饋輸出電壓從二次側(cè)，以維持輸出精度。

　　光耦合器的傳輸延遲、老化和增益變化使復(fù)環(huán)補(bǔ)償和反激變換器的穩(wěn)定性復(fù)雜化，同時(shí)限制了變換器的瞬態(tài)響應(yīng)。此外，光耦合器消耗功率，增加電源的成本和物理尺寸。設(shè)計(jì)一個(gè)高性能變壓器與額外的繞組可以采取大量的時(shí)間，因?yàn)橛幸粋€(gè)有限的選擇現(xiàn)成的變壓器。最后，使用一個(gè)額外的繞組增加了變壓器的物理尺寸和成本。

　　Fortunately， recent advances in power conversion technology have made low-power isolated converters much easier to design. By incorporating a primary-side sensing scheme and running the converter in boundary mode， Linear Technology’s no-opto flyback converters， such as the LT3574 and LT8300， simplify the design of flyback converters by eliminating the need for an opto-coupler， external MOSFET， secondary-side reference voltage， and extra transformer winding. Its boundary mode， which is a variable-frequency， current-mode， control switching scheme （more on this shortly）， also results in improved regulation over the full line， load， and temperature ranges. According to Linear， boundary mode also permits the use of a smaller transformer compared to equivalent continuous conduction mode （CCM） designs. These flyback solutions are popular in isolated power supplies ranging from less than a watt to tens of watts.