參考設(shè)計(jì)給出了電路原理圖(圖1)、材料清單(表1)和特性參數(shù)(圖2–7)。MAX15046的關(guān)鍵指標(biāo)如下。
設(shè)計(jì)規(guī)格與配置
輸入電壓:18V至36V
輸出電壓:1.2V
輸出電流:13.4A
輸出電壓紋波:12mVP-P
輸入電壓紋波:180mVP-P
開(kāi)關(guān)頻率:250kHz
效率:VIN= 18V、13.4A輸出電流時(shí)效率為82%;VIN= 36V、13.4A輸出電流時(shí)效率為74%

圖1. MAX15046 buck電源電路原理圖,F(xiàn)SW = 250kHz。
| Designator | Value | Description | Part Number | Manufacturer | Package | Quantity |
| C1 | 470μF/50V | Capacitor | EEVFK1H471M | Panasonic | Electrolytic | 1 |
| C2 | 0.1μF/50V | Capacitor | GRM188R71H104K | Murata | 603 | 1 |
| C3 | 1μF/50V | Capacitor | GRM21BR71H105K | Murata | 805 | 1 |
| C4 | 4.7μF/6.3V | Capacitor | GRM188R60J475K | Murata | 603 | 1 |
| C5 | 2.2μF | Capacitor | GRM21BR71H105K | Murata | 603 | 1 |
| C6, C7, C7X | 10μF/50V | Capacitor | GRM55D470H106K3 | Murata | 2220 | Z |
| C8 | 0.47μF/16V | Capacitor | GRM188R71C477K | Murata | 603 | 1 |
| C9 | 2700pF/50V | Capacitor | GRM2165C1H272JA | Murata | 805 | 1 |
| C10 | 470μF/6.3V | Capacitor | EEFSX0D471E4 | Panasonic | 7.3mm x 4.3mm x 1.9mm | 1 |
| C11 | 100μF/6.3V | Capacitor | GRM32ER60JA017ME20L | Murata | 1210 | 1 |
| C11 | 100μF/6.3V | Capacitor | GRM32ER60J107ME20L | Murata | 1210 | 1 |
| C12 | 100μF/6.3V | Capacitor | GRM32ER60J107ME20L | Murata | 1210 | 1 |
| C13 | 68pF/50V | Capacitor | GRM1885C1H680J | Murata | 603 | 1 |
| C14 | 100pF/50V | Capacitor | GRM39COG101J50D500 | Murata | 603 | 1 |
| C15 | 10nF/50V | Capacitor | GRM1887R1H103KA01D | Murata | 603 | 1 |
| C16 | 820pF/50V | Capacitor | GRM39COG821J50D500 | Murata | 603 | 1 |
| C17 | Open | Capacitor | ||||
| C18 | 22μF/6.3V | Capacitor | GRM31CR70J226KE19L | Murata | 1206 | 1 |
| C19 | 1μF/6.3V | Capacitor | GRM188R70J105KA01D | Murata | 603 | 1 |
| R3 | 10Ω | Resistor | Resistor | Multisource | 603 | 1 |
| R4 | 51kΩ | Resistor | Resistor | Multisource | 603 | 1 |
| R5 | 2.2Ω | Resistor | Resistor | Multisource | 603 | 1 |
| R7 | 1Ω | Resistor | Resistor | Multisource | 603 | 1 |
| R8 | Open | Resistor | ||||
| R9 | 19.1kΩ | Resistor | Resistor | Multisource | 603 | 1 |
| R10 | 6.04kΩ | Resistor | Resistor | Multisource | 603 | 1 |
| R11 | 4kΩ | Resistor | Resistor | Multisource | 603 | 1 |
| R12 | 86.6kΩ | Resistor | Resistor | Multisource | 603 | 1 |
| R13 | 86.6kΩ | Resistor | Resistor | Multisource | 603 | 1 |
| R14 | 68.1kΩ | Resistor | Resistor | Multisource | 603 | 1 |
| R15 | 49.9Ω | Resistor | Resistor | Multisource | 603 | 1 |
| R16 | 0 | Resistor | Resistor | Multisource | 603 | 1 |
| R17 | 0 | Resistor | Resistor | Multisource | 603 | 1 |
| L1 | 2.2μH/20A | Inductor | IHLP5050EZER2R2M01 | Vishay | 13.22mm x 12.90mm x 5.00mm | 1 |
| N2 | 60V, 18.5A | n-Channel MOSFET | SI7478DP | Vishay | PowerPAK SO-8 | 1 |
| D1 | 0.5A, 60V | Schottky Diode | ZHCS506TA | Zetex | SOT23 | 1 |
| U1 | MAX15046 | PWM Controller | MAX15046 | Analog | 16 PIN TQFN | 1 |
特性參數(shù)

圖2. 不同輸入電壓下,總效率與負(fù)載電流關(guān)系曲線。

圖3. 穩(wěn)態(tài)輸入電壓、輸出電壓和柵極信號(hào)。
Ch1:開(kāi)關(guān)節(jié)點(diǎn)電壓
Ch2:輸入電壓
Ch3:輸出電壓

圖4. 穩(wěn)態(tài)輸入紋波峰峰值和輸出紋波峰峰值。
Ch2:輸入電壓紋波
Ch3:輸出電壓紋波

圖5. VIN= 28V、負(fù)載電流為13.4A時(shí)的軟啟動(dòng)。
Ch2:輸入電壓
Ch3:輸出電壓

圖6. 關(guān)閉輸入電源時(shí)的軟停止。
Ch2:輸入電壓
Ch3:輸出電壓

圖7. 負(fù)載短路時(shí)的輸出電壓和柵極信號(hào)。
Ch3:輸出電壓
Ch4:高邊開(kāi)關(guān)的柵極信號(hào)
電路板布局

圖8. 參考設(shè)計(jì)采用MAX15046降壓電源,雙層板。
審核編輯:郭婷
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