One benefit of high-frequency switching is the fast loop response. This translates to smaller footprint and lower cost, because the ceramic capacitors can be used. The MAX1945 internal switch step-down regulator is designed for high-frequency switching. It can be switched at 1MHz. Its peak current mode control architecture allows simple Type II compensation (R2 and C2) to achieve high bandwidth, further reducing the external component count. As shown in Figure 1, for 6A output, only two 1210 footprint ceramic capacitors are needed to meet the 50% step load change, thus greatly reducing the output capacitor size when compared to switching at 500kHz or less. A second benefit is due to the low ESR of the ceramic capacitors. Large inductor ripple current is allowed to achieve the 1% ripple voltage requirement.The value of the output inductor is 0.68µH, resulting in a footprint of 8.2mm x 8.2mm for 6A output current, further reducing buck converter size. Figure 1. Schematic of the MAX1945 for 1MHz all ceramic capacitor application. In Figure 1, the output inductor is the largest external component with the footprint of 8.2mm x 8.2mm. However, with the new developments at TOKO and Sumida we expect the inductor size to be reduced to 7.2mm x 7.2mm, further reducing the regulator footprint size. Figure 2 shows the output ripple voltage, whose peak-to-peak value is less than 10mV for 1.8V output, well less than 1%. Figure 2. Output ripple voltage and LX switching waveforms. Figure 3 shows the load transient response. With two 47µF ceramic output capacitors, the maximum output voltage deviation can meet ±5% for 50% step load change (3A). In addition, the transient response finishes within 10us. Table 1 lists the bill of materials. Figure 3. Step load transient response: output current from 1A to 4.2A back to 1A. The output voltage back to regulation within 10us for 50% step load change. Table 1. Bill of Materials Component Function Part Number Vendor L1 Output inductor 0.68µH/12A, 6mΩ ESR max, 4783-T007 Sumida C1 Input filtering cap. 2 x 22µF/6.3V ceramic caps. 20mΩ max each cap. LMK325BJ226MM Taiyo Yuden C2 Loop compensation capacitor 100pF/10V, X7R ceramic capacitor   C3 Bootstrap cap. 0.1µF/10V, X7R ceramic capacitor   C4 Reference bypass cap. 0.22F/6.3V, X7R ceramic capacitor   C5 Output filtering cap. 2 x 47µF/6.3V ceramic caps. 20mΩ max each cap. JMK325BJ476 Taiyo Yuden C6 Input filtering cap 0.1µF/10V, X7R ceramic capacitor   R1 Vcc filtering resistor 10Ω, 5%   R2 Loop compensation resistor 100k, 1%   D1 Bootstrap diode BAT54A, Shorttky diode Central Semiconductor IC1 6A step-down regulator MAX1945R MAXIM 相关型号   APP 1782: Nov 11, 2002 MAX1945 1MHz、1%精度、6A内置开关、降压型调节器 完整的数据资料 (PDF, 856kB) 免费样品 自动更新 需要自动接收最新发布的应用笔记吗？请订阅EE-Mail™ (English only)。 我们期待您的反馈！ 喜欢？不喜欢？有待改善？或为我们提供建议？请与我们联系 — 我们将根据您的意见或建议改善我们的工作。 网页评价或提供建议   下载，PDF格式 (55kB)  AN1782, AN 1782, APP1782, Appnote1782, Appnote 1782