SNVSBY6 October 2021 LM61430-Q1
Diode emulation prevents reverse current though the inductor, which requires a lower frequency needed to regulate given a fixed peak inductor current. Diode emulation also limits ripple current as frequency is reduced. With a fixed peak current, as output current is reduced to zero, frequency must be reduced to near zero to maintain regulation.
The LM61430-Q1 has a minimum peak inductor current setting while in auto mode. Once current is reduced to a low value with fixed input voltage, on-time is constant. Regulation is then achieved by adjusting frequency. This mode of operation is called PFM mode regulation.