When NPWR_BTN is not enabled, power-up is controlled by ACT, shown in Figure 8-4.

When ACT is high, the ENx output sequence starts and NRST is de-asserted RST_DLY[3:0] time after the last ENx. The power-up sequence is defined by PWR_ENx registers, for more information see Table 8-31.

When NPWR_BTN is enabled, ACT is used as AUTO/BUTTON power-on strap option. With ACT strapped to VDD, a short push on NPWR_BTN will start the power-up sequence; with ACT strapped to GND, the power-up sequence will automatically start once VDD is valid. From SHDN2 state a short push on NPWR_BTN is always required to start the power-up sequence. See Figure 8-5 for details. When power-up is triggered, the ENx output sequence starts and NRST is de-asserted CTL_2.RST_DLY[3:0] time after the last ENx.