Figure 8-13 shows a functional block diagram of the power-good function in a secondary device. During initialization, the device presets FF1 and FF2, which pulls down the PG pin and forces the device to operate in DCM. When the device completes the soft start, it resets FF2, which turns off Q1. However, in a stacked configuration, all devices share the same PG signal, and therefore the PG pin stays low until all devices in the stack have completed the soft start. When that happens, FF1 is reset and the converters operate in CCM.

Figure 8-13 Power-Good Functional Block Diagram (Secondary Device)