The device detects low-side (LS) current during off-time and high-side (HS) current during on-time. The device responds to an overcurrent fault when soft start is done.

Low-side Overcurrent Protection:

The device monitors valley current during HS off-time. If the inductor current is above the valley current limit threshold, the next HS pulse is skipped, the LS FET remains on, and an internal counter increments. This counter counts as long as inductor current is higher than valley at the clock edge. If the current goes below valley at the clock edge, the counter is reset.

If the counter is able to count to 16 cycles without reset, then it is identified as a current limit fault and the device hiccups. The device enters hiccup for seven cycles of internal soft start and then attempts a normal soft start.

High-side Overcurrent Limit:

The device implements a high-side overcurrent limit-to-limit peak current and prevents the inductor from saturation when a short circuit happens. When the device hits peak current limit, the HS FET turns off and the LS FET turns on. Once the inductor current clears the valley limit, the HS FET turns on at the next clock edge.

Negative Overcurrent Protection:

When the inductor current goes below the negative overcurrent threshold, the low-side FET turns off. It turns on again at the next clock pulse.