2.1.3.1 PLL Behavior at Brownout Condition

The Microchip SoC Products Group recommends using monotonic power supplies or voltage regulators to ensure proper power-up behavior. Power ramp-up should be monotonic at least until VCC and VCCPLLx exceed brownout activation levels. The VCC activation level is specified as 1.1V worst-case (see Figure 2-2 for more details).

When PLL power supply voltage and/or VCC levels drop below the VCC brownout levels (0.75V ± 0.25V), the PLL output lock signal goes low and/or the output clock is lost. Refer to the “Power-Up/-Down Behavior of Low Power Flash Devices” chapter of the ProASIC3 FPGA Fabric User’s Guide for information on clock and lock recovery.