ZHCSQD0 April 2022 LM5013-Q1
PRODUCTION DATA
The LM5013-Q1 manages overcurrent conditions with cycle-by-cycle current limiting of the peak inductor current. The current sensed in the high-side MOSFET is compared every switching cycle to the current limit threshold (4.5 A). There is a 100-ns leading-edge blanking time following the high-side MOSFET turn-on transition to eliminate false tripping off the current limit comparator. To protect the converter from potential current runaway conditions, the LM5013-Q1 includes a tOFF timer that is proportional to VIN and VOUT that is enabled if a 4.5-A peak current limit is detected. As shown in Figure 7-1, if the peak current in the high-side MOSFET exceeds 4.5 A (typical), the present cycle is immediately terminated regardless of the programmed on time (tON), the high-side MOSFET is turned off and the tOFF timer is activated. This allows the peak inductor current to fall from 4.5-A peak to an acceptable value to ensure no excessive current in the power stage. This method folds back the switching frequency to prevent overheating and limits the average output current to less than 4.5 A to ensure proper short-circuit and heavy-load protection of the LM5013-Q1. This innovative current limit scheme enables ultra-low duty-cycle operation, permitting large step-down voltage conversions while ensuring robust protection of the converter.