從一個單一的同步降壓轉(zhuǎn)換器生成多個輸出簡單

　　許多系統(tǒng)板需要多個電壓軌驅(qū)動各種半導(dǎo)體集成電路遍布董事會。例如，考慮一個現(xiàn)代機(jī)頂盒（機(jī)頂盒）。它包括設(shè)備從系統(tǒng)級芯片（SoC）芯片的邏輯、Wi-Fi、HDMI、以太網(wǎng)PHY接口，如USB和SDIF和。此外，它還集成了RF / IF功能和時鐘，因為所有這些設(shè)備消耗大量的功率，風(fēng)扇需要冷卻。為了盡量減少噪音，一個好的設(shè)計也分離模擬和數(shù)字電源軌。其結(jié)果是，SOC需要的核心電壓為1.8 V或更低，而其I / OS需要一個3.3 V電源。同樣，一個USB端口使用5 V電源，所以風(fēng)扇?？傊?，一個單一的系統(tǒng)板需要多個電源軌操作。

　　傳統(tǒng)上，產(chǎn)生這些多電壓，設(shè)計師們已經(jīng)使用多個開關(guān)變換器或低壓差穩(wěn)壓器（LDO）降壓電壓從最近電壓總線。除了添加到系統(tǒng)板的成本和空間，使用多個開關(guān)穩(wěn)壓器或LDO也意味著功耗和整體效率低。另一種，簡單的方法是從一個單一的同步降壓型穩(wěn)壓器產(chǎn)生多種電壓。1

　　Multi-output synchronous converters

　　Although， single-synchronous step-down regulators generating multiple-output voltages are available， such as Linear Technology’s LM5006， they use coupled inductors and associated multiple external MOSFETs， as well as diode rectification to generate two or more voltage outputs. A typical LM5006-based step-down converter using coupled inductors is shown in Figure 1. Additional components required generating two or more outputs use more space and add cost while compromising efficiency， and thereby defeating its use. Hence， to minimize external components while overcoming the cumbersome of designing transformers or coupled inductors， suppliers like Texas Instruments and Linear Technology have introduced next-generation integrated multi-output synchronous step-down switching regulators that simplify such tasks from a smaller footprint without compromising efficiency.