The output of the pick lower block goes into a pick higher block, which selects the higher of the pick lower block output and the burst mode threshold setting.
The burst mode multiplexer selects between burst mode threshold (BMT) and ground. During soft start, the multiplexer selects ground. The startup process is open loop and controlled by the soft start ramp. Burst mode is not enabled during soft start phase.
After soft start, the higher of the two inputs are sent to the differential amplifier. The output of the block is FBLessThanBMT. This output is sent to the waveform generator state machine to control burst mode and system external shut down.