attiny25v ATMEL Corporation, attiny25v Datasheet - Page 43

• Manufacturer Part Number: attiny25v
• Description: Microcontroller With 2/4/8k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

8.2.3
8.2.4
2586K–AVR–01/08
Brown-out Detection
Watchdog Reset
Figure 8-4.
ATtiny25/45/85 has an On-chip Brown-out Detection (BOD) circuit for monitoring the V
during operation by comparing it to a fixed trigger level. The trigger level for the BOD can be
selected by the BODLEVEL Fuses. The trigger level has a hysteresis to ensure spike free
Brown-out Detection. The hysteresis on the detection level should be interpreted as V
V
When the BOD is enabled, and V
8-5), the Brown-out Reset is immediately activated. When V
(V
expired.
The BOD circuit will only detect a drop in V
longer than t
Figure 8-5.
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
“Watchdog Timer” on page 44
BOT
BOT+
+ V
in
HYST
Figure
CC
BOD
/2 and V
External Reset During Operation
Brown-out Reset During Operation
INTERNAL
TIME-OUT
given in
8-5), the delay counter starts the MCU after the Time-out period t
RESET
RESET
V
CC
BOT-
“System and Reset Characteristics” on page
= V
BOT
for details on operation of the Watchdog Timer.
- V
CC
HYST
decreases to a value below the trigger level (V
V
BOT-
/2.
CC
if the voltage stays below the trigger level for
CC
V
t
TOUT
BOT+
increases above the trigger level
ATtiny25/45/85
170.
TOUT
BOT-
. Refer to
TOUT
in
CC
BOT+
Figure
level
has
43
=