ZHCSEQ3D February 2016 – December 2022 LM5165
PRODUCTION DATA
The output capacitor, COUT, filters the inductor ripple current and stores energy to meet the load current requirement when the LM5165 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.