The LMR436x0-Q1 can have two behaviors while lightly loaded. One behavior, called auto mode operation, allows for seamless transition between normal current mode operation while heavily loaded and highly efficient light-load operation. The other behavior, called FPWM mode, maintains full frequency even when unloaded. Which mode the LMR436x0-Q1 operates in depends on which variant from this family is selected. Note that all parts operate in FPWM mode when synchronizing frequency to an external signal.
The light-load operation is employed in the LMR436x0-Q1 only in auto mode. The light load operation employs two techniques to improve efficiency:
Note that while these two features operate together to improve light load efficiency, they operate independently.