The brown-out
reset (BOR) monitor supervises the external supply (VDD) and asserts or de-asserts a
BOR violation to SYSCTL. The primary responsibility of the BOR circuit is to ensure
that the external supply is maintained high enough to enable correct operation of
internal circuits, including the core regulator. The BOR threshold reference is
derived from the internal bandgap circuit. The threshold itself is programmable and is
always higher than the POR threshold. During cold start, after VDD passes the POR+
threshold the bandgap reference and BOR circuit are started. The device is then held in
a BOR state until VDD passes the BOR0+ threshold. Once VDD passes BOR0+, the BOR monitor
releases the device to continue the boot process, and the PMU is started. (The BOR
triggered waveform is shown in
Section 3.2.3).