簡介：

The followingdesign note features the latest techniques for minimizing the  standby power consumption of a 65 W notebook adapter.
 
主要特點：

NCP1246是一個新的固定頻率電流模式控制器具有動態(tài)自供電。此功能極大地簡化了設(shè)計輔助電源和VCC電容通過激活供貨期間控制器的內(nèi)部啟動電流源啟動，瞬變，鎖存器，待機等設(shè)備中含有一種特殊高壓檢測器，其檢測應(yīng)用程序從AC輸入拔除線和觸發(fā)的X2的放電電流。 HV結(jié)構(gòu)允許在掉電檢測以及。它具有一個基于計時器的故障檢測，確保檢測過載和一個可調(diào)的補償，以幫助保持最大功率的輸入電壓無關(guān)。由于頻率折返，控制器具有優(yōu)良的在輕負載條件下的效率，同時還實現(xiàn)了非常低待機功耗。內(nèi)部頻率抖動，斜坡補償和一個多功能閂鎖輸入該控制器出色的候選人，強勁的電源設(shè)計。一個專門的關(guān)閉模式，可以達到非常低的空載通過“沉睡”了整個裝置的輸入功耗，從而控制電路的功率消耗最小化。

•固定頻率電流模式操作（65 kHz和100 kHz頻率選項）                                 

•頻率折返，然后跳躍模式，最大化性能輕載和待機狀態(tài)下

•定時器過載保護鎖存（選項A）自動恢復(fù)功能（選項B）操作                        

•高電壓電流源，掉電檢測和動態(tài)自供電，VCC電路的簡化設(shè)計

•調(diào)頻軟化EMI簽名                                                                                         

•可調(diào)節(jié)過載保護家屬的散裝電壓

•閉鎖開關(guān)量輸入相結(jié)合的壓制保護感應(yīng)輸入                                                 

•高達28 V的VCC操作，具有過壓檢測

•500/800 mA源出/吸入驅(qū)動器峰值電流能力                                                  

 •10 ms軟啟動

•內(nèi)部熱關(guān)斷                                                                                                  

•空載待機功耗<30 mW的

•X2電容EMI過濾器排氣功能                                                                           

•這些器件是無鉛和無鹵/ BFR免費

2.

The NCP4353 and NCP4354 are secondary side SMPS controllers designed for use in applications which require extremely low no load power consumption. The device is capable of detecting ’no load’ conditions and entering the power supply into a low consumption OFF mode. During OFF mode, the primary side controller is turned off and energy is provided by the output capacitors thus eliminating the power consumption required to maintain regulation. During OFF mode, the output voltage relaxes and is allowed to decrease to an adjustable level. Once more energy is required, the NCP4353 or NCP4354 automatically restarts the primary side controller.

During normal power supply operation, the devices provide integrated voltage feedback regulation, replacing the need for a shunt regulator. The A versions include a current regulation loop in addition to voltage regulation. Feedback control as well as ONOFF signal can be provided with only one optocoupler.

The NCP4354 includes a LED driver pin implemented with an open drain MOSFET driven by a 1 kHz square wave with a 12.5% duty cycle for indication purpose. The NCP4354 is available in SOIC-8 package and the NCP4353 is available in TSOP-6.

方案特點：

When focusing on the no load power consumption of an adapter design, the key losses need to be identified. Switching losses and circuit biasing must be minimized or

eliminated completely. The latest technique for minimizing losses during no load is to turn off the Ac-Dc controller and allow the output voltage to drop. Because the adapter is not supplying power, a drop in output voltage is viewed as acceptable. The following design utilizes the NCP1246 flyback controller and the NCP4354A  secondary side controller to realize this technique. Both controllers have built-in features focused on minimizing no load input power consumption.

Constant Voltage Constant Current Regulation (CCCV)

Very Low Input Power at Light and No Load

High Efficiency Across the Entire Load Range

Overpower Protection

Universal Mains Operation

方案參考原理圖：


圖1 參考原理圖

參考PCB圖：

              

               圖2： 參考PCB圖

詳情請見： http://www.onsemi.cn/pub_link/Collateral/EVBUM2138-D.PDF