Silicon Labs

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6 Power-On Reset and Brownout Detector

BLE121LR includes a power-on reset (POR), providing correct initialization during device power on. It also

includes a brownout detector (BOD) operating on the regulated 1.8-V digital power supply only. The BOD

protects the memory contents during supply voltage variations which cause the regulated 1.8-V power to drop

below the minimum level required by digital logic, flash memory, and SRAM. When power is initially applied,

the POR and BOD hold the device in the reset state until the supply voltage rises above the power-on-reset

and brownout voltages.