MAX5073双通道降压转换器工作于2MHz开关频率的参考设计
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摘要：MAX5073是一款可工作于降压或升压模式的双路转换器。作为双路降压转换器工作时，该器件两路输出可分别提供高达2A和1A的输出电流。该参考设计主要说明MAX5073作为降压转换器、工作于2MHz开关频率的应用。高开关频率允许使用更小尺寸的无源元件，并工作在汽车应用中AM波段以外的频率。
本文给出了采用MAX5073双通道降压型转换器、工作于2MHz开关频率下的详细参考设计。该设计可用于电路板空间受限的应用，因为较高的开关频率允许采用更小尺寸的无源元件。此外，该电源解决方案可用于汽车电子(带有抛负载保护)，即需要开关频率工作在AM调频波段以外的产品。例如，汽车仪表盘和信息娱乐系统。
该参考设计的关键规格在下面列出，并给出了应用所需的详细原理图(图1)及材料清单(表1)。
规格
输入电压：5.5V至16V
第1路转换器输出电压 = 3.3V/2A (最大值)
第2路转换器输出电压 = 2.5V/1A (最大值)
每路转换器的开关频率(fSW) = 2MHz
环境温度(TA) = -40°C至+85°C
图1. MAX5073参考设计
表1. 材料清单
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
实际测量电路获得的数据给出了器件的效率指标，详细内容参见表2和表3。
表2. VOUT2禁止时的效率指标
fSW = 2MHz、LOUT = 4.7µH、COUT = 22µF/6.3V (陶瓷电容)
VIN (V)IIN (A)VOUT1 (V)IOUT1 (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. VOUT1禁止时的效率指标
fSW = 2MHz、LOUT = 4.7µH、COUT = 22µF/6.3V (陶瓷电容)
VIN (V)IIN (A)VOUT2 (V)IOUT2 (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
在稳定性方面，图2和图3所示为每路输出的波特图，详细说明了每路输出的增益和相位。
图2. 3.3V/1.4A VOUTPUT波特图
图3. 2.5V/0.6A VOUTPUT波特图
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