Looking at reference design PMP9546 (Schematic at http://www.ti.com/lit/df/tidr919/tidr919.pdf ) I have a question that needs some information about the internals of the LM43600. If the power supply is shut off, but the battery is still connected, will the battery discharge through L1 and back into pins 1 and 2 of the LM43600? I am wondering if a diode is needed between L1 and the battery?