Pulse-frequency-modulation (PFM) mode is activated when peak current is lower than I_PEAK-MIN, only in auto mode. Peak current is kept constant and V_OUT is regulated by frequency. Efficiency is greatly improved by lowered switching losses, especially at very light loads.

In PFM operation, a small DC positive offset appears on V_OUT. The lower the frequency is folded back in PFM, the more the DC offset is on V_OUT. See the V_OUT regulation curves in the Section 9.2.3. If the DC offset on V_OUT is not acceptable, a dummy load at V_OUT, or lower R_FBT and R_FBB resistance values can be used to reduce the offset. Alternatively, the device can be run in FPWM mode where the switching frequency is constant, and no offset is added to affect the V_OUT accuracy unless t_{ON_MIN} is reached.