JAJSOW6C November 2007 – January 2024 TPS5420-Q1
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.
Once 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 may still occur when using cycle-by-cycle current limiting. A second mode of current limiting is used, i.e., 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. Once the hiccup time duration is complete, the regulator restarts under control of the slow start circuit.