Figure 3-4 shows the sequence of power up when a 24-VAC system is plugged in. The battery was already connected and powering the 3V3 rail before 24 VAC was plugged in. Upon plugging in the 24-VAC, the system begins charging the battery and takes over powering the system load. RectOut reaches steady state in approximately 240 ms from the initial 24-VAC plugin. Variances in the 24-VAC transformer cause variances in the steady-state rise time as can be observed by comparing Figure 3-4, Figure 3-8, and Figure 3-10. Note that the LMR36520 rail is tested at node PWRIn, which is directly on the output of the ORing solution. The 3V3 rail exhibits no distinguishable transient response during the transition from battery power to 24-VAC power. Figure 3-8 and Figure 3-10 provide start-up tests to account for tolerances present in 24-VAC transformers and show comparable results to Figure 3-4. Immediate loss of 24-VAC power is tested in Figure 3-5, Figure 3-9, and Figure 3-11. As is evident by the smooth nature of RectOut in these tests, the battery was fully charged and no significant load current was being supplied. Upon a 24-VAC power loss, RectOut discharges most of the rectification caps energy in 1 second for a nominal 24 VAC. Figure 3-6 and Figure 3-7 show a 24-VAC loss while a load on the 3V3 bus is demanding current. The rectification caps discharge considerably faster than no load conditions. The BMOut rail drops in voltage as the BM24072 transitions to battery power. The 3V3 rail exhibits no significant transient response to the loss of 24 VAC and remains regulated and supplying to output load.