4.6.1.1.2 Under Voltage Detection (1.8V Supply)

The under-voltage condition is triggered when the 1.8V core supply drops below a 1.665V (-7.5% nominal) threshold causing the assertion of the 1.8V supply Under-Voltage (UV18) status bit in the OPEN Alliance Status 1 (OA_STATUS1) register. In case of the 1.8V supply, both the LAN8650 externally sourced and the LAN8651 internally generated LDO 1.8V supplies are monitored. If the interrupt status is not masked via the 1.8V Under-Voltage Interrupt Mask (UV18M) bit in the OPEN Alliance Mask 1 (OA_MASK1) register, the IRQ_N pin will assert. The 1.8V Under-Voltage status bit will not be cleared until the supply voltage rises above the minimum threshold.

To prevent false brown-out detection due to power supply noise, the supply voltage must remain below the minimum threshold for greater than 5.12 μs before the under-voltage condition will be triggered. The debounce time may be adjusted by configuring the 1.8V supply Under-Voltage Filter Time (UV18FTM) field of the Miscellaneous (MISC) register.