7.3.13 Overvoltage and Undervoltage Protection for VDDQ

TPS51116 monitors a resistor divided feedback voltage to detect overvoltage and undervoltage. If VDDQSET is connected to V5IN or GND, the feedback voltage is made by an internal resistor divider inside VDDQSNS pin. If an external resistor divider is connected to VDDQSET pin, the feedback voltage is VDDQSET voltage itself. When the feedback voltage becomes higher than 115% of the target voltage, the OVP comparator output goes high and the circuit latches as the high-side MOSFET driver OFF and the low-side MOSFET driver ON.

The device monitors the VDDQSNS pin voltage directly and if it becomes greater than 4 V, it turns off the high-side MOSFET driver. When the feedback voltage becomes lower than 70% of the target voltage, the UVP comparator output goes high and an internal UVP delay counter begins counting. After 32 cycles, TPS51116 latches OFF both top and low-side MOSFETs. This function is enabled after 1007 cycles of SMPS operation to ensure startup.