ATA5771_10 Datasheet, PDF (49/219 Pages) ATMEL Corporation – Output Power of 8dBm at 315MHz / 7.5dBm at 433.92 MHz / 5.5dBm at 868.3MHz

Atmel ATA5771/73/74
4.11.1.5
Watchdog Reset
When the Watchdog times out, it will generate a short reset pulse of one CK cycle duration.
On the falling edge of this pulse, the delay timer starts counting the Time-out period t_TOUT. See
Section 4.11.3 “Watchdog Timer” on page 50 for details on operation of the Watchdog Timer.
Figure 4-18. Watchdog Reset During Operation
CC
CK
4.11.2
Internal Voltage Reference
The Atmel^® ATtiny44V 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 or the ADC.
4.11.2.1
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 Section 8.3.4 “System and Reset Characterizations” on page 190. 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).
3. When the ADC is enabled.
Thus, when the BOD is not enabled, after setting the ACBG bit or enabling the ADC, the user
must always allow the reference to start up before the output from the Analog Comparator or
ADC is used. To reduce power consumption in Power-down mode, the user can avoid the
three conditions above to ensure that the reference is turned off before entering Power-down
mode.
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