TI boost devices with down-mode start-up multiplex the start-up strategy during output short conditions (TPS61299). Whenever output voltage drops below the input, the device enters down mode. I_LIMIT limits the inductor current until Vout drops below 0.5V. After that, the soft start-up current limit applies and clamps the current peak to 350mA. Figure 3-3 show the output short behavior.

Figure 3-3 TPS61299 Into Short-Circuit Waveform

The device stays in down-mode start-up procedure until the short circuit releases and the device can start up.

Figure 3-4 TPS61299 Short-Circuit Release Waveform