ACE7333C

28V, 3A, 500KHz Synchronous Step-Down DC/DC Converter

VER 1.2

8

Applications Information

Setting Output Voltages

The external resistor divider is used to set the output voltage. The feedback resistor R1 also sets the

feedback loop bandwidth with the internal compensation capacitor. The recommended value of the R1

should below 100K to provide optimal transient response. R2 is then given by:

Selecting the Inductor

Use a 2.2μH-to-6.8μH inductor with a DC current rating of at least 25% higher than the maximum load

current for most applications. For highest efficiency, select an inductor with a DC resistance less than

15mΩ. For most designs, derive the inductance value from the following equation:

Where ΔIL is the inductor ripple current. Choose an inductor current approximately 30% of the maximum

load current. The maximum inductor peak current is:

Under light-load conditions (below 100mA), use a larger inductor to improve efficiency.

Selecting the Output Capacitor

The output capacitor maintains the DC output voltage. Use ceramic, tantalum, or low-ESR electrolytic

capacitors. Use low ESR capacitors to limit the output voltage ripple. Estimate the output voltage ripple

with: