在很多网络和电信应用系统中，有多种稳压电源电压。很多电源电压要求提供大电流、合理的尺寸和效率、以及优异的负载瞬态响应。这篇文章提供了采用开关频率为300kHz的双buck控制器MAX5066的详细参考设计方案。
该参考设计的关键规格在下面列出，并给出了应用中所需的详细电路原理图(图1)和材料清单(表1)。
规格
- VIN = 5.15V (-0.4V, +0.4V)
- VOUT1 = 1.2V ±48mV/IOUT1 = 0至8.5A (包括瞬态)
- 转换器1的输出电压纹波：12mVP-P
- 转换器1的负载瞬态响应：负载从10%变化至60%时，18mVP-P
- VOUT2 = 3.3V ±132mV/IOUT2 = 0至4.4A (包括瞬态)
- 转换器2的输出电压纹波：27mVP-P
- 转换器2的负载瞬态响应：负载由10%变化至60%时，40mVP-P
- 转换器1和2的复合效率：满负载时93.38%
- 温度范围：-40°C 至+85°C
图1. MAX5066参考设计显示了5.1V转1.2V/8.5A和3.3V/4.4A的DC-DC转换器；fSW = 295kHz。
| Designator | Value | Description | Part | Footprint | Manufacturer | Quantity |
| C50, C71 | 4.7µF/6.3V | Capacitors | JMK107BJ475MA-T | 0603 | Taiyo Yuden | 2 |
| C60 | 470µF/6.3V | Capacitors | APXA6R3ARA471MHC0G | 3.1mm x 4.2mm x 2.2mm | Nippon Chemi-Con | 1 |
| C61, C62, C64, C72, C74, C75, C76, C77 | 10µF/10V | Capacitors | LMK212BJ106M | 0805 | Taiyo Yuden | 8 |
| C63, C73, C86, C87 | 1.0µF/16V | Capacitors | EMK107BJ105KA-T | 0603 | Taiyo Yuden | 4 |
| C65, C79 | 220nF/16V | Capacitors | EMK107BJ224MA-T | 0603 | Taiyo Yuden | 2 |
| C67, C68, C81, C83, C84 | 100nF/16V | Capacitors | EMK105BJ104KV-FR | 0402 | Taiyo Yuden | 5 |
| C69 | 100pF | Capacitor | UMK105CH180JW | 0402 | Taiyo Yuden | 1 |
| C70, C85 | 1.0µF/6.3V | Capacitors | JMK105BJ105KV | 0402 | Taiyo Yuden | 2 |
| C82 | OPEN | Capacitor | OPEN | 0402 | OPEN | 1 |
| L60, L61 | 2.3µH | Inductors | MVR1278 | 7.8mm x 11.5mm | Coilcraft | 2 |
| Q60, Q61 | n-channel 30V | nMOSFETs | SI7114DN | PowerPAK 1212-8 | Vishnay-Siliconix | 2 |
| Q62, Q63, Q64 | n-channel 20V | nMOSFETs | SI7114DN | PowerPAK 1212-8 | Vishnay-Siliconix | 3 |
| R60, R72 | 1Ω | Resistors | SMD, 1%, 63mW | 0402 | Vishay | 2 |
| R62, R73, R74, R75, R76, R77 | 0.01Ω | Resistors | RL1220T, 250mW | 0805 | Susumu | 6 |
| R62, R73, R74, R75, R76, R77 | 0.01Ω | Resistors | RL1220T, 250mW | 0805 | Susumu | 6 |
| R64 | 0.039Ω | Resistor | RL1220T, 250mW | 0805 | Susumu | 1 |
| R65 | 1.2kΩ | Resistor | SMD, 1%, 63mW | 0402 | Vishay | 1 |
| R66 | 3.3kΩ | Resistor | SMD, 1%, 63mW | 0402 | Vishay | 1 |
| R67, R83 | 1MΩ | Resistors | SMD, 1%, 63mW | 0402 | Vishay | 2 |
| R69 | 43kΩ | Resistor | SMD, 1%, 63mW | 0402 | Vishay | 1 |
| R70 | 4.7kΩ | Resistor | SMD, 1%, 63mW | 0402 | Vishay | 1 |
| R71 | 41.2Ω | Resistor | SMD, 1%, 63mW | 0402 | Vishay | 1 |
| R78 | 0.027Ω | Resistor | RL1220T, 250mW | 0805 | Susumu | 1 |
| R79 | 910Ω | Resistor | SMD, 1%, 63mW | 0402 | Vishay | 1 |
| R80 | 22kΩ | Resistor | SMD, 1%, 63mW | 0402 | Vishay | 1 |
| R81 | 20kΩ | Resistor | SMD, 1%, 63mW | 0402 | Vishay | 1 |
| R82 | 100kΩ | Resistor | SMD, 1%, 63mW | 0402 | Vishay | 1 |
| D60, D61 | 30V/200mA | Schottky Diodes | RB521S30T1 | SOD-523 | ON Semiconductor | 2 |
| D62, D63 | 30V/30mA | Schottky Diodes | RB751 | SOD-523 | ON Semiconductor | 2 |
| U60 | MAX5066 | PWM Controller | MAX5066AUI | 28-TSSOP-EP | Maxim | 1 |
表2中总结了每个转换器的效率数据，显示出每路输出都具有高效率，如图2所示。
| VIN(V) | IIN(A) | VOUT1(V) | IOUT1(A) | VOUT2(v) | IOUT2(A) | Efficiency (%) |
| 5.1402 | 5.0780 | 1.1814 | 8.5008 | 3.2558 | 4.4016 | 93.38% |
| 5.1347 | 4.5728 | 1.1853 | 72.6491 | 3.2636 | 3.96 | 95.73% |
| 5.361 | 4.0605 | 1.1891 | 6.8012 | 3.2713 | 3.5244 | 95.06% |
| 5.1500 | 3.5440 | 1.1928 | 5.9558 | 3.2791 | 3.0836 | 94.32% |
| 5.1441 | 3.0432 | 1.1967 | 5.1030 | 3.2870 | 2.6435 | 94.54% |
| 5.1497 | 2.5398 | 1.2005 | 4.2507 | 3.2948 | 2.2086 | 94.65% |
| 5.1522 | 2.0337 | 1.2044 | 3.3988 | 3.3030 | 1.7608 | 94.57% |
| 5.1490 | 1.5407 | 1.2083 | 4.2557 | 3.3111 | 1.3232 | 94.15% |
| 5.1465 | 1.0441 | 1.2122 | 1.7073 | 3.3194 | 0.8815 | 92.97% |
| 5.380 | 0.5472 | 1.2163 | 0.8455 | 3.3279 | 0.4419 | 88.88% |
图2. 整体效率相对总输出功率的关系
图3和图4中显示了控制器输出电压与其输出负载电流之间的关系。
图3. 第一个控制器输出电压与其输出负载电流之间的关系
图4. 第二个控制器输出电压与其输出负载电流之间的关系
图5和6中给出各路稳压输出的负载瞬态响应性能。
图5. 1.2V时，负载在0.85A和5.1A之间变化时，输出在10µs内阶跃18mV
图6. 3.3V时，负载在0.44A和2.64A之间变化时，输出在10µs内阶跃40mV
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