ACE727C

600KHz, 16V, 2A Synchronous Step-Down Converter

VER 1.2

6

Selecting the Output Capacitor

The output capacitor (C2) is required to maintain the DC output voltage. Ceramic, tantalum, or low ESR

electrolytic capacitors are recommended. Low ESR capacitors are preferred to keep the output voltage

ripple low. The output voltage ripple can be estimated by:

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

capacitor. In the case of ceramic capacitors, the impedance at the switching frequency is dominated by

the capacitance. The output voltage ripple is mainly caused by the capacitance. For simplification, the

output voltage ripple can be estimated by:

In the case of tantalum or electrolytic capacitors, the ESR dominates the impedance at the switching

frequency. For simplification, the output ripple can be approximated to:

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

ACE727C can be optimized for a wide range of capacitance and ESR values.