for current saving if fast or frequent changes between the turbo mode and the non turbo mode are required the external buck 104 may hold the low voltage level in order to be readily available when needed a further embodiment provides that the external buck 104 may be directly controlled by the pmic 102 however this control need not be exclusive to the pmic 102 a still further embodiment provides that external control may be provided by the main device processor fig3 shows the combined output voltage of the pmic 102 and the external buck 104 u 1 u 2 and also shows the control signals for the external buck 104 u 2 before operation of the embodiments described herein commences the pmic 102 drives the amperage up to a predetermined level in the normal mode in step 1 the external buck 104 is enabled in step 2 the activation signal and voltage selector en and vsel is set to activate the higher voltage mode the pmic 102 voltage is then increased to a predetermined level in step 3 this voltage is below the voltage level provided in the turbo mode in step 4 the output voltage vout reaches the turbo mode level at that point the load current is driven by the external buck 104 entry into the turbo mode occurs in step 5 the turbo mode is ready in step 6 after passage of a predetermined amount of time when the output.