ACE726C

500KHz, 18V, 2A Synchronous Step-Down Converter

VER 1.1

8

Applications Information

Setting Output Voltages

The external resistor divider is used to set the output voltage (see Typical Application on page 1). The

feedback resistor R1 also sets the feedback loop bandwidth with the internal compensation capacitor.

Choose R1 to be around 300kΩ for optimaltransient response.R2isthengivenby:

Selecting the Inductor

Use a

2.2μH-to-10μH inductor with a DC current rating of at least 25% percent 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. Themaximum inductor peak current is:

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

Selecting the Output Capacitor

The output capacitor (C2) 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: