On Semi NCP1236 65W笔记本电脑离线适配器设计方案
On Semi公司的NCP1236是新型固定频率电流模式控制器,具有动`态自给电源(DSS),从而简化了辅助电源的设计,可调过功率补偿,VCC工作高达28V并具有压检测.驱动能力500mA,软起动时间4.0ms,内部具有热关断.主要用在笔记本电脑,LCD和打印机的AC/DC适配器,离线电池充电器,消费类电子电源等.本文介绍了NCP1236主要特性,方框图, 采用NCP1236的反激转换器以及65W笔记本电脑离线适配器参考设计主要特性,电路图,材料清单和PCB元件布局图.
The NCP1236 is a new fixed−frequency current−mode controller featuring Dynamic Self−Supply (DSS). This device is pin−to−pin compatible with the previous NCP12xx families.
The DSS function greatly simplifies the design of the auxiliary supply and the VCC capacitor by activating the internal startup current source to supply the controller during transients.
Due to frequency foldback, the controller exhibits excellent efficiency in light load condition while still achieving very low standby power consumption. Internal frequency jittering, ramp compensation, and a versatile latch input make this controller an excellent candidate for converters where components cost is the key constraints.
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