This jumper is used to choose between PWM and PFM/PWM modes of operation. Setting the jumper across PWM forces the device into the low-noise fixed-frequency pulse width modulation (PWM) mode. Setting the jumper across PWM/PFM enables the power save mode where the device enters apulse frequency modulation mode (PFM) at light to medium load currents, which reduces quiescent current and switching frequency to a minimum to achieve highest efficiency over the entire load current range.

Additionally an external clock between 600 kHz and 1200 kHz can be applied to pin 2 of J2 (SYNC) in order to synchronize the converter to an external clock.