4.16.1.1 Under-Voltage Detection (3.3V Supply)

The device is able to detect a voltage source brown-out condition. The under-voltage condition is triggered when the VDDA or VDDAU supplies drop below a 3.05V (-7.5% nominal) threshold causing the assertion of the 3.3V supply Under-Voltage (UV33) status bit in the Status 2 (STS2) register. If the interrupt status is not masked via the 3.3V Under-Voltage Interrupt Mask (UV33M) bit in the Interrupt Mask 2 (IMSK2) register, the IRQ_N pin will assert. The 3.3V 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 200 μs before the under-voltage condition will be triggered. The debounce time may be adjusted by configuring the 3.3V supply Under-Voltage Filter Time (UV33FTM) field of the Analog Control 5 (ANALOG5) register.