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ATmega161(L)
1228B–09/01
Internal Voltage
Reference
ATmega161 features an internal voltage reference with a nominal voltage of 1.22V. This
reference is used for Brown-out Detection and it can be used as an input to the Analog
Comparator.
Voltage Reference
Enable Signals and Start-
up Time
The voltage reference has a start-up time that may have an influence on the way it
should be used. The maximum start-up time is TBD. To save power, the reference is on
during the following situations only:
1.
When BOD is enabled (by programming the BODEN fuse)
2.
When the bandgap reference is connected to the Analog Comparator (by setting
the AINBG bit in ACSR)
Thus, when BOD is not enabled, after setting the AINBG bit, the user must always allow
the reference to start up before the output from the Analog Comparator is used. The
bandgap reference uses approximately 10
µ
A, and to reduce the power consumption in
Power-down mode, the user can turn off the reference when entering this mode.