PI超薄笔记本电脑设计:The notebook adapter power supply shown in Figure 1 features the Power Integrations® TOPSwitch®-HX TOP261LN in a fl yback confi guration, using a universal input to deliver a 65 W, 19.7 V Figure 1. 65 W Notebook Adapter Schematic. output. The features designed into the TOP261LN (U11) provide the type of protection important to a notebook adapter such as OVP, latching shutdown, and hysteretic thermal-overload protection. All TOPSwitch-HX devices feature EcoSmart® to provide constant effi ciency over full specifi ed load range. EcoSmart utilizes multicycle modulation (MCM), a proprietary, automatic function that eliminates special operating modes usually necessary at specifi c load thresholds. This simplifi es and optimizes circuit design for meeting future energy effi ciency regulation changes without redesign. Capacitor C66 at the input reduces differential mode EMI, while Resistors R63 and R64 provide a discharge path upon AC removal to prevent shock. Bridge rectifi er D25 rectifi es the AC. Bulk capacitors C63 and C64 fi lter the resulting DC. A line-sensing network (D26 and C70) enables implementation of a fast AC reset function. A clamp network (C43, R93, R62, D18, VR2, and R72) prevents voltage spikes at the Drain (D) pin upon MOSFET switch turn-off. Y-capacitor C41 reduces common-mode EMI, as does common-mode inductor L1.