无光反激拓扑简化了隔离DCDC变换器的设计

　　无光反激拓扑简化了隔离DC/DC变换器的设计

　　除了被用在电信和数据通信系统中，直流输出也在许多其他噪声敏感的应用如汽车蓄电池的充电要求，中间总线电压为各种电子负载，和工业品。虽然反激拓扑是流行的隔离DC / DC转换器应用，由于它相对简单和成本较低的替代孤立的拓扑结构，设计传统的反激式是不容易的，因为变压器需要精心设计，环补偿可以是复杂的。此外，它需要一个光耦或额外的变压器绕组反馈输出电压从二次侧，以维持输出精度。

　　光耦合器的传输延迟、老化和增益变化使复环补偿和反激变换器的稳定性复杂化，同时限制了变换器的瞬态响应。此外，光耦合器消耗功率，增加电源的成本和物理尺寸。设计一个高性能变压器与额外的绕组可以采取大量的时间，因为有一个有限的选择现成的变压器。最后，使用一个额外的绕组增加了变压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.