From Figure 9-8, locate the 5-V output voltage section. In the load current column, choose the load current line that is closest to the current required for the application; for this example, use the 0.5-A line. In the maximum input voltage column, select the line that covers the input voltage required for the application; in this example, use the 15-V line. The rest of this line shows the recommended inductors and capacitors that provides the best overall performance.

The capacitor list contains both through hole electrolytic and surface mount tantalum capacitors from four different capacitor manufacturers. TI recommends using both the manufacturers and the manufacturer's series that are listed in Table 9-5.

In this example, aluminum electrolytic capacitors from several different manufacturers are available with the range of ESR numbers needed:

  120-μF, 2-5V Panasonic HFQ Series

  120-μF, 2-5V Nichicon PL Series

For a 5-V output, a capacitor voltage rating at least 7.5 V or more is required. But, in this example, even a low ESR, switching grade, 120-μF, 10-V aluminum electrolytic capacitor can exhibit approximately 400 mΩ of ESR (see Figure 9-2 for the ESR vs voltage rating). This amount of ESR can result in relatively high output ripple voltage. To reduce the ripple to 1% of the output voltage, or less, a capacitor with a higher voltage rating (lower ESR) must be selected. A 16-V or 25-V capacitor reduces the ripple voltage by approximately half.