Under light-load conditions, the iso-buck converter output voltage increases excessively due to the transformer leakage inductance and parasitic capacitance. Normally, a minimum load of 10% to 20% of the full load is sufficient to keep the converter output voltage regulation within +/-5%. If the minimum load cannot be guaranteed or the supplied circuitry is sensitive to the target supply being exceeded, it is recommended to use a zener diode at the output to limit the voltage and thus protect the supplied circuitry.