The LTC3108 takes a “systems level” approach to solving a complex problem. It can convert the low voltage source and manage the energy between multiple outputs. The AC voltage produced on the secondary winding of the transformer is boosted and rectified using an external charge pump capacitor (from the secondary winding to pin C1) and the rectifiers internal to the LTC3108. This rectifier circuit feeds current into the VAUX pin, providing charge to the external VAUX capacitor and then the other outputs. The internal 2.2V LDO can support a low power processor or other low power ICs. The LDO is powered by the higher value of either VAUX or V_OUT. This enables it to become active as soon as VAUX has charged to 2.3V while the V_OUT storage capacitor is still charging. In the event of a step load on the LDO output, current can come from the main V_OUT capacitor if VAUX drops below V_OUT. The LDO output is typically 3mA. The V_STORE capacitor may be a very large value (thousands of microfarads or even Farads) to provide holdup at times when the input power may be lost.