The LM5160A when used in either the buck or the Fly-Buck application, can also be biased by an external voltage source for improved efficiency requirements. The LM5160A can be externally biased to VOUT by connecting VCC to VOUT through a diode as shown in the Fly-Buck application circuit in Figure 35. In this dual output rail Fly-Buck application circuit, the VCC pin is externally diode connected (D2) to VOUT (primary). The design procedure with the LM5160A, for both Buck and Fly-Buck configurations, remains the same as with LM5160. The voltage applied to the VCC pin, either from VOUT or an external supply must be between 9 V and 13 V.