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
| Designator | Value | Description | Part | Footprint | Manufacturer | Quantity |
| C1 | 100µF/35V | Capacitor | EEVFK1V101P | 8mm x 10.2mm | Panasonic | 1 |
| C2, C3, C4, C17, C18 | 0.1µF/25V | Capacitors | GRM188R71E104KA01D | 603 | Murata | 5 |
| C5, C6, C7 | 22µF/6.3V | Capacitors | GRM31CR60J226KE19 | 1206 | Murata | 2 |
| C8, C9 | 10µF/25V | Capacitors | GRM31CR61E106KA12 | 1206 | Murata | 1 |
| C10, C12 | 2.2nF | Capacitors | GRM188R71H222JA01 | 603 | Murata | 2 |
| C11 | 560pF | Capacitor | GRM188R71H561KA01 | 603 | Murata | 1 |
| C13, C14 | 22pF | Capacitors | GRM1885C1H220JA01 | 603 | Murata | 2 |
| C15 | 1nF | Capacitor | GRM18871H102KA01 | 603 | Murata | 1 |
| C16 | 4.7µF/6.3V | Capacitor | GRM188R60J475KE19B | 603 | Murata | 1 |
| C19 | 0.22µF/10V | Capacitor | GRM188R71A224KA01 | 603 | Murata | 1 |
| C20 | 0.01µF | Capacitor | GRM188R71H103KA01J | 603 | Murata | 1 |
| D1, D2 | 30V, 500mA | Schottky diodes | MBR0530 | SOD123 | ON Semiconductor | 2 |
| D3 | 40V, 3A | Schottky diode | MBRS340 | SMC | ON Semiconductor | 1 |
| D4 | 40V, 2A | Schottky diode | MBRS240 | SMB | ON Semiconductor | 1 |
| L1, L2 | 4.7µH | Inductors | IHLP2525-CZ | 6.86mm x 6.47mm x 3.18mm | Vishay | 1 |
| R1, R11 | 100kΩ | Resistors | SMD, 1%, 0.125W | 603 | Vishay | 2 |
| R2 | 6.8Ω | Resistor | SMD, 1%, 0.125W | 603 | Vishay | 1 |
| R3 | 4.7Ω | Resistor | SMD, 1%, 0.125W | 603 | Vishay | 1 |
| R4, R8, R10 | 1.18kΩ | Resistors | SMD, 1%, 0.125W | 603 | Vishay | 3 |
| R5, R9 | 27.4kΩ | Resistors | SMD, 1%, 0.125W | 603 | Vishay | 2 |
| R6 | 10kΩ | Resistor | SMD, 1%, 0.125W | 603 | Vishay | 1 |
| R7 | 12.7kΩ | Resistor | SMD, 1%, 0.125W | 603 | Vishay | 1 |
| R12 | 2.2Ω | Resistor | SMD, 1%, 0.125W | 603 | Vishay | 1 |
| R13 | 6.19kΩ | Resistor | SMD, 1%, 0.125W | 603 | Vishay | 1 |
| R14 | 8.76kΩ | Resistor | SMD, 1%, 0.125W | 603 | Vishay | 1 |
| U1 | MAX5073 | Dual buck converter | MAX5073ETI+ | 32-TQFN_EP (5mm x 5mm) | Maxim | 1 |
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 (%) |
| 14.007 | 0.065732 | 3.3371 | 0.1018 | 36.8973371 |
| 14.010 | 0.183690 | 3.3339 | 0.5122 | 66.3542117 |
| 14.005 | 0.267750 | 3.3321 | 0.8032 | 71.3722082 |
| 14.007 | 0.329490 | 3.3309 | 1.0112 | 72.9812485 |
| 14.005 | 0.449290 | 3.3298 | 1.4007 | 74.1230723 |
| 14.002 | 0.584520 | 3.3281 | 1.8203 | 74.0201375 |
| 14.001 | 0.650260 | 3.3267 | 2.0150 | 73.6279304 |
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 (%) |
| 14.008 | 0.044533 | 2.5350 | 0.1075 | 43.6845979 |
| 14.008 | 0.067144 | 2.5337 | 0.2049 | 55.1967881 |
| 14.003 | 0.087638 | 2.5337 | 0.3010 | 62.1452787 |
| 14.004 | 0.109076 | 2.5337 | 0.4003 | 66.3986847 |
| 14.005 | 0.133680 | 2.5337 | 0.5122 | 69.3178710 |
| 14.005 | 0.155350 | 2.5338 | 0.6097 | 71.0058542 |
| 14.008 | 0.255976 | 2.5334 | 1.0001 | 70.6597037 |
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