Rainbow Electronics ATtiny2313 - Manual (Page 39)

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ATtiny2313
2543A–AVR–08/03
Internal Voltage
Reference ATtiny2313 features an internal bandgap reference. 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 influence the way it should be used.
The start-up time is given in Table 18. To save power, the reference is not always turned
on. The reference is on during the following situations:
1. When the BOD is enabled (by programming the BODLEVEL [2..0] Fuse).
2. When the bandgap reference is connected to the Analog Comparator (by setting
the ACBG bit in ACSR).
Thus, when the BOD is not enabled, after setting the ACBG bit, the user must always
allow the reference to start up before the output from the Analog Comparator is used. To
reduce power consumption in Power-down mode, the user can avoid the three condi-
tions above to ensure that the reference is turned off before entering Power-down mode.
Note: 1. Values are guidelines only. Actual values are TBD.
Table 18. Internal Voltage Reference Characteristics (1)
Symbol Parameter Condition Min Typ Max Units
V
BG
Bandgap reference voltage V
CC
= 2.7V,
T
A
= 25°C
1.0 1.1 1.2 V
t
BG
Bandgap reference start-up time V
CC
= 2.7V,
T
A
= 25°C
40 70 µs
I
BG
Bandgap reference current
consumption V
CC
= 2.7V,
T
A
= 25°C
15 µA