ZHCSES0C March 2016 – December 2022 LM5165-Q1
PRODUCTION DATA
The output capacitor, COUT, filters the inductor ripple current and stores energy to meet the load current requirement when the LM5165-Q1 is in sleep mode. The output ripple has a base component of amplitude VOUT/123 related to the 10-mV typical feedback comparator hysteresis in PFM. The wakeup time from sleep to active mode adds a ripple voltage component that is a function of the output current. Approximate the total output ripple by Equation 21.
Also, the output capacitance must be large enough to accept the energy stored in the inductor without a large deviation in output voltage. Setting this voltage change equal to 0.5% of the output voltage results in:
In general, select the capacitance of COUT to limit the output voltage ripple at full load current, ensuring that it is rated for worst-case RMS ripple current given by IRMS = IPK(PFM)/2. In this design example, choose a 10-µF, 6.3-V ceramic output capacitor with X7R dielectric and 0805 footprint.