8-bit AVR Microcontrollers

BOD Disable

When the Brown-out Detector (BOD) is enabled by BODLEVEL fuses, the BOD is actively monitoring the power supply voltage during a sleep period. To save power, it is possible to disable the BOD by use of software for some of the sleep modes. The sleep mode power consumption will then be at the same level as when BOD is globally disabled by fuses. If BOD is disabled in software, the BOD function is turned off immediately after entering the sleep mode. Upon wake-up from sleep, BOD is automatically enabled again. This ensures safe operation in case the VCC level has dropped during the sleep period.

When the BOD has been disabled, the wake-up time from sleep mode will be approximately 60 μs to ensure that the BOD is working correctly before the MCU continues executing code.

BOD disable is controlled by the BOD Sleep bit in the MCU Control Register (MCUCR.BODS). Writing this bit to '1' turns off the BOD in relevant sleep modes, while a zero in this bit keeps BOD active. The default setting, BODS=0, keeps BOD active.

Note: Writing to the BODS bit is controlled by a timed sequence and an enable bit.