SLVS675E August 2006 – January 2024 TPS5410
PRODUCTION DATA
Overcurrent limiting is implemented by sensing the drain-to-source voltage across the high-side MOSFET. The drain to source voltage is then compared to a voltage level representing the overcurrent threshold limit. If the drain-to-source voltage exceeds the overcurrent threshold limit, the overcurrent indicator is set true. The system ignores the overcurrent indicator for the leading edge blanking time at the beginning of each cycle to avoid any turn-on noise glitches.
After overcurrent indicator is set true, overcurrent limiting is triggered. The high-side MOSFET is turned off for the rest of the cycle after a propagation delay. The overcurrent limiting scheme is called cycle-by-cycle current limiting.
Sometimes under serious overload conditions such as short-circuit, the overcurrent runaway can still happen when using cycle-by-cycle current limiting. A second mode of current limiting is used, for example hiccup mode overcurrent limiting. During hiccup mode overcurrent limiting, the voltage reference is grounded and the high-side MOSFET is turned off for the hiccup time. After the hiccup time duration is complete, the regulator restarts under control of the slow-start circuit.