摘要：MAX5073是一款可工作于降壓或升壓模式的雙路轉(zhuǎn)換器。作為雙路降壓轉(zhuǎn)換器工作時(shí)，該器件兩路輸出可分別提供高達(dá)2A和1A的輸出電流。該參考設(shè)計(jì)主要說(shuō)明MAX5073作為降壓轉(zhuǎn)換器、工作于2MHz開關(guān)頻率的應(yīng)用。高開關(guān)頻率允許使用更小尺寸的無(wú)源元件，并工作在汽車應(yīng)用中AM波段以外的頻率。

本文給出了采用MAX5073雙通道降壓型轉(zhuǎn)換器、工作于2MHz開關(guān)頻率下的詳細(xì)參考設(shè)計(jì)。該設(shè)計(jì)可用于電路板空間受限的應(yīng)用，因?yàn)檩^高的開關(guān)頻率允許采用更小尺寸的無(wú)源元件。此外，該電源解決方案可用于汽車電子(帶有拋負(fù)載保護(hù))，即需要開關(guān)頻率工作在AM調(diào)頻波段以外的產(chǎn)品。例如，汽車儀表盤和信息娛樂(lè)系統(tǒng)。

該參考設(shè)計(jì)的關(guān)鍵規(guī)格在下面列出，并給出了應(yīng)用所需的詳細(xì)原理圖(圖1)及材料清單(表1)。


規(guī)格

輸入電壓：5.5V至16V
第1路轉(zhuǎn)換器輸出電壓 = 3.3V/2A (最大值)
第2路轉(zhuǎn)換器輸出電壓 = 2.5V/1A (最大值)
每路轉(zhuǎn)換器的開關(guān)頻率(fSW) = 2MHz
環(huán)境溫度(TA) = -40°C至+85°C

圖1. MAX5073參考設(shè)計(jì)

表1. 材料清單

DesignatorValueDescriptionPartFootprintManufacturerQuantityC1100µF/35VCapacitorEEVFK1V101P8mm x 10.2mmPanasonic1C2, C3, C4, C17, C180.1µF/25VCapacitorsGRM188R71E104KA01D603Murata5C5, C6, C722µF/6.3VCapacitorsGRM31CR60J226KE191206Murata2C8, C910µF/25VCapacitorsGRM31CR61E106KA121206Murata1C10, C122.2nFCapacitorsGRM188R71H222JA01603Murata2C11560pFCapacitorGRM188R71H561KA01603Murata1C13, C1422pFCapacitorsGRM1885C1H220JA01603Murata2C151nFCapacitorGRM18871H102KA01603Murata1C164.7µF/6.3VCapacitorGRM188R60J475KE19B603Murata1C190.22µF/10VCapacitorGRM188R71A224KA01603Murata1C200.01µFCapacitorGRM188R71H103KA01J603Murata1D1, D230V, 500mASchottky diodesMBR0530SOD123ON Semiconductor2D340V, 3ASchottky diodeMBRS340SMCON Semiconductor1D440V, 2ASchottky diodeMBRS240SMBON Semiconductor1L1, L24.7µHInductorsIHLP2525-CZ6.86mm x 6.47mm x 3.18mmVishay1R1, R11100kΩResistorsSMD, 1%, 0.125W603Vishay2R26.8ΩResistorSMD, 1%, 0.125W603Vishay1R34.7ΩResistorSMD, 1%, 0.125W603Vishay1R4, R8, R101.18kΩResistorsSMD, 1%, 0.125W603Vishay3R5, R927.4kΩResistorsSMD, 1%, 0.125W603Vishay2R610kΩResistorSMD, 1%, 0.125W603Vishay1R712.7kΩResistorSMD, 1%, 0.125W603Vishay1R122.2ΩResistorSMD, 1%, 0.125W603Vishay1R136.19kΩResistorSMD, 1%, 0.125W603Vishay1R148.76kΩResistorSMD, 1%, 0.125W603Vishay1U1MAX5073Dual buck converterMAX5073ETI+32-TQFN_EP (5mm x 5mm)Maxim1

實(shí)際測(cè)量電路獲得的數(shù)據(jù)給出了器件的效率指標(biāo)，詳細(xì)內(nèi)容參見表2和表3。

表2. V_OUT2禁止時(shí)的效率指標(biāo)
f_SW = 2MHz、L_OUT = 4.7µH、C_OUT = 22µF/6.3V (陶瓷電容)

V_IN (V)I_IN (A)V_OUT1 (V)I_OUT1 (A)Efficiency (%)14.0070.0657323.33710.101836.897337114.0100.1836903.33390.512266.354211714.0050.2677503.33210.803271.372208214.0070.3294903.33091.011272.981248514.0050.4492903.32981.400774.123072314.0020.5845203.32811.820374.020137514.0010.6502603.32672.015073.6279304

表3. V_OUT1禁止時(shí)的效率指標(biāo)
f_SW = 2MHz、L_OUT = 4.7µH、C_OUT = 22µF/6.3V (陶瓷電容)

V_IN (V)I_IN (A)V_OUT2 (V)I_OUT2 (A)Efficiency (%)14.0080.0445332.53500.107543.684597914.0080.0671442.53370.204955.196788114.0030.0876382.53370.301062.145278714.0040.1090762.53370.400366.398684714.0050.1336802.53370.512269.317871014.0050.1553502.53380.609771.005854214.0080.2559762.53341.000170.6597037

在穩(wěn)定性方面，圖2和圖3所示為每路輸出的波特圖，詳細(xì)說(shuō)明了每路輸出的增益和相位。

圖2. 3.3V/1.4A VOUTPUT波特圖

圖3. 2.5V/0.6A VOUTPUT波特圖