Self-Tracking Zero-Current Detection Based on Switching Node Ringing for High-Current Buck Converters

A self-tracking zero-current detection (ZCD) for buck converters is presented. The proposed scheme detects the switching node ringing and adaptively adjusts the turn-off time of the low-side switch to achieve accurate ZCD. It combines the advantages of two traditional methods: Zero-I Cross Detector and CCM/DCM Boundary Detector. It is particularly suitable for DC-DC converters with heavy load current applications. Based on a $0.18 \mu \mathrm{~m}$ BCD process, the proposed ZCD is verified in a 12 A buck converter with $4.5 \mathrm{~m} \Omega$ low-side power switch.