ZHCS688I November 2011 – March 2018 TPS65217
PRODUCTION DATA.
The advanced fast-response voltage-mode control scheme of the two converters lets the use of small ceramic capacitors with a typical value of 10 µF, without having large output-voltage undershoots and overshoots during heavy load transients. Ceramic capacitors having low ESR values result in the lowest output voltage ripple and are therefore recommended.
If ceramic output capacitors are used, the capacitor RMS ripple-current rating must always meet the application requirements. Use Equation 6 to calculate the RMS ripple current (IRMSCout).
At the nominal load current, the inductive converters operate in PWM mode and the overall output voltage ripple is the sum of the voltage spike caused by the output capacitor ESR plus the voltage ripple caused by charging and discharging the output capacitor as shown in Equation 7.
where
At light-load currents, the converters operate in power-save mode, and the output-voltage ripple depends on the output capacitor value. The output-voltage ripple is set by the internal comparator delay and the external capacitor. The typical output-voltage ripple is less than 1% of the nominal output voltage.