ZHCS573I August 2010 – April 2018 LM25119
PRODUCTION DATA.
The output capacitors smooth the inductor ripple current and provide a source of charge during transient loading conditions. For this design example, a 680-µF electrolytic capacitor with 10-mΩ ESR was selected as the main output capacitor. The fundamental component of the output ripple voltage is approximated with Equation 21 and the example (Equation 22 and Equation 23).
Two 22-µF low ERS or ESL ceramic capacitors are placed in parallel with the 680-µF electrolytic capacitor, to further reduce the output voltage ripple and spikes.
K < 1 | 1 <— K —> 3 | K > 3 | ||
---|---|---|---|---|
Cross talk | Sub-harmonic oscillation may occur | Higher | Lower | Introduces additional pole near cross-over frequency |
Peak inductor current with short output condition | Lower | Higher | ||
Inductor size | Smaller | Larger | ||
Power dissipation of Rs | Higher | Lower | ||
Efficiency | Lower | Higher |