SWRU543B January 2019 – June 2025 CC3230S , CC3230SF , CC3235MODS , CC3235MODSF , CC3235S , CC3235SF
BROWNOUT is the state where the supply voltage falls below the chip brownout threshold. For wide voltage mode, Vbrownout = 2.1 V. The hibernate controller, 2 × 32-bit general-purpose retention register inside the hibernate controller, the 32.768-kHz crystal oscillator, and the RTC counter are not impacted by BROWNOUT state and continue to function. Once the supply voltage rises above Vbrownout, the chip reboots.
BLACKOUT is the condition where the CC32xx PMU incorporates a continuous time coarse analog supply voltage monitor that forces the PMU, including the hibernate controller, into a reset state where Vsupply < Vblackout. Vblackout is typically 1.4 V and varies with temperature.
BLACKOUT ensures that there is a deterministic reset of the control registers and flags inside the hibernate module just before the supply falls, to ensure that the system operations are terminated reliably. In this way, when a proper supply level is restored, the PMU starts from a clean reset state without any corrupt control bits carried over from last session. The hibernate controller, 2 × 32-bit general-purpose retention register inside the hibernate controller, the 32.768-kHz crystal oscillator, and the RTC counter are all reset during BLACKOUT. For a functional perspective, the effect of BLACKOUT is similar to that of pulling down the chip reset pin (nRESET).