The TPSI3050 and TPSI3050S have two modes of operation: two-wire mode and three-wire mode.

In two-wire mode, the power on the primary side is provided directly by the EN pin. Setting EN high causes power transfer to the secondary side. As power transfers, the secondary rails, VDDM and VDDH, begin to rise. After sufficient power is available on the secondary side, VDRV is asserted high. Setting EN low causes VDRV to assert low and halts power transfer to the secondary side.

In three-wire mode, the power on the primary side is provided by a dedicated, low output impedance supply connected to VDDP. In this case, power transfer is independent from the enable state. If VDDP power is present, power is transferred from the primary side to the secondary side regardless of the EN state. In steady state conditions, when sufficient power is available on the secondary side, setting EN high causes VDRV to assert high. Setting EN low causes VDRV to assert low.

In standard enable, available only on the TPSI3050, VDRV follows the state of the EN pin and is used in most load switch applications. In one-shot enable mode, available only on the TPSI3050S in three-wire mode, when a rising transition occurs on EN, VDRV is asserted high momentarily and then automatically asserted low, forming a one-shot pulse on VDRV. This event is useful for driving SCR devices that require only one burst of power to trigger. To re-trigger VDRV, EN must first transition low, followed by another rising transition.