The ADP5135 combines three high performance buck regulators （BUCK1， BUCK2， and BUCK3）。 It is available in a 24-lead， 4 mm × 4 mm LFCSP. The high switching frequency of the buck regulators enables tiny multilayer external components and minimizes the board space. When the MODE pin is set to high， the buck regulators operate in forced pulse-width modulation （PWM） mode. When the MODE pin is set to low， the buck regulators operate in PWM mode only when the load is above a predefined threshold. When the load current falls below this predefined threshold， the regulator operates in power save mode （PSM）， improving the light load efficiency. BUCK1 and BUCK2 operate in synchronization， and BUCK3 operates out of phase to reduce the input capacitor requirement. Regulators in the ADP5135 are activated through dedicated enable pins. The default output voltages can be externally set in the adjustable version， or factory programmable to a wide range of preset values in the fixed voltage version.