ACE7263C

27V 2A 500KHz Synchronous Step-Down DC/DC Converter

VER 1.2

8

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:

Where L is the inductor value and RESR is the equivalent series resistance (ESR) of the output capacitor.

For ceramic capacitors, the capacitance dominates the impedance at the switching frequency and causes

most of the output voltage ripple. For simplification, estimate the output voltage ripple with:

For tantalum or electrolytic capacitors, the ESR dominates the impedance at the switching frequency. For

simplification, the output ripple can be approximated with:

The characteristics of the output capacitor also affect the stability of the regulation system. The

ACE7263C can be optimized for a wide range of capacitance and ESR values.

Selecting the external boost diode

It is recommended to add an external Boost Diode to improve efficiency and stability in these situations

when the input voltage is fixed at 5.0V. Any a readily and cheap diode can meet the need of these

application such as 1N4148.