限制Low Loads變換器DC/DC變換器效率的技術(shù)

　　拉伸功率預(yù)算是設(shè)計(jì)工程師開(kāi)發(fā)電池驅(qū)動(dòng)產(chǎn)品的常見(jiàn)挑戰(zhàn)。消費(fèi)者期望從每一個(gè)新產(chǎn)品迭代中獲得更多的功能和更長(zhǎng)的運(yùn)行時(shí)間，但是，因?yàn)殡姵丶夹g(shù)進(jìn)展非常緩慢，這證明越來(lái)越困難。

　　開(kāi)關(guān)DC / DC轉(zhuǎn)換器有助于提高電池壽命，因?yàn)樗鼈兊母咝视兄跍p少電力消耗。然而，在輸出電流范圍內(nèi)，效率不是恒定的，在低負(fù)荷時(shí)會(huì)顯著下降。對(duì)于電池供電的設(shè)備來(lái)說(shuō)，這尤其是一個(gè)問(wèn)題，通常需要長(zhǎng)時(shí)間處于待機(jī)狀態(tài)或休眠狀態(tài)。這種低負(fù)荷運(yùn)行效率低，電池壽命計(jì)算錯(cuò)誤，產(chǎn)品運(yùn)行時(shí)間短，用戶(hù)失望。

　　本文將仔細(xì)研究如何在負(fù)載下切換DC/DC轉(zhuǎn)換器的效率，解釋為什么會(huì)出現(xiàn)這種情況，并指出一些產(chǎn)品包含技術(shù)來(lái)緩解這個(gè)問(wèn)題。

　　Squeezing out the power

　　Processor chips have improved in performance roughly in harmony with Gordon Moore’s 1965 prediction that the number of transistors on a chip doubles every 24 months. （Actually， the performance has tended to double every 18 months because not only are there more transistors， but they also operate faster.）

　　Meanwhile， batteries have improved relatively slowly. For example， Lithium ion （Li ion） cells， the mainstay power source for high-demand portable devices such as cell phones and digital cameras， have improved in energy density by only about 7 percent a year （the improvement is mainly due to incremental engineering refinements）。