Enable Input and Current Limit State MachineThe enable input circuit at the EN/UV pin consists of a lowimpedance source follower output set at 1.2 V. The currentthrough the source follower is limited to 115 μA. When thecurrent out of this pin exceeds the threshold current, a lowlogic level (disable) is generated at the output of the enablecircuit, until the current out of this pin is reduced to less thanthe threshold current. This enable circuit output is sampledat the beginning of each cycle on the rising edge of the clocksignal. If high, the power MOSFET is turned on for that cycle(enabled). If low, the power MOSFET remains off (disabled).Since the sampling is done only at the beginning of each cycle,subsequent changes in the EN/UV pin voltage or current duringthe remainder of the cycle are ignored.