GaN FET is usually used for high frequency soft-switching and the detection of FET current zero-crossing is needed for system control. LMG3427R030 integrates a zero current detection (ZCD) circuit that provides a digital feedback signal when the drain-to-source current is positive. When the IN pin signal goes high, the ZCD circuit includes a blanking time t_{ZCD_Blank}, to prevent nuisance ZCD triggering during the turn-on transient. Following the blanking period, the ZCD circuit monitors the drain-to-source current. If the current is negative, a pulse-output with a width of t_{WD_ZVD} is set on the ZCD pin after detecting the zero-crossing point, with a delay time of t_{zc_Det}. If the current is positive, the pulse output is set on the ZCD pin immediately, as indicated in the timing diagrams below.

Figure 7-10 ZCD timing diagram when FET turns on into negative current

Figure 7-11 ZCD timing diagram when FET tuns on into positive current