SLVUCU8 January 2024
Figure 3-18 and Figure 3-19 show the start-up and shutdown waveforms for U2 with EN. In Figure 3-18, the input voltage is initially applied and the output is inhibited by pulling EN to GND using an external function generator. When the EN voltage is increased above the enable-threshold voltage, the start-up sequence begins and the output voltage ramps up to the externally set value. In Figure 3-19, the external function generator pulls EN to ground and the TPS54KC23 shuts down.