An initiator assembly that includes a housing assembly, an exploding foil initiator, an input charge and an output charge. The exploding foil initiator is received in the housing assembly and includes a bridge, a flyer and a barrel. The flyer overlies the bridge and is disposed between the barrel and the bridge. The barrel defines a barrel aperture. The input charge, which is formed of a secondary explosive, is received in the housing assembly and is disposed in-line with the barrel aperture. The output charge assembly is received in the housing assembly and is segregated from the input charge.