ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 41

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Watchdog Reset
2570A–AVR–09/04
teresis to ensure spike free Brown-out Detection. The hysteresis on the detection level
should be interpreted as V
Table 17. BODLEVEL Fuse Coding
Note:
Table 18. Brown-out Characteristics
When the BOD is enabled, and V
in Figure 19), the Brown-out Reset is immediately activated. When V
the trigger level (V
out period t
The BOD circuit will only detect a drop in V
for longer than t
Figure 19. Brown-out Reset During Operation
When the Watchdog times out, it will generate a short reset pulse of one CK cycle dura-
tion. On the falling edge of this pulse, the delay timer starts counting the Time-out period
t
TOUT
Symbol
V
t
BOD
HYST
. Refer to page 43 for details on operation of the Watchdog Timer.
BODLEVEL 2..0 Fuses
1. V
INTERNAL
devices where this is the case, the device is tested down to V
production test. This guarantees that a Brown-Out Reset will occur before V
to a voltage where correct operation of the microcontroller is no longer guaranteed.
The test is performed using BODLEVEL = 10 for ATmega325/3250/645/6450V and
BODLEVEL = 01 for ATmega325/3250/645/6450L.
TOUT
TIME-OUT
BOT
Parameter
Brown-out Detector Hysteresis
Min Pulse Width on Brown-out Reset
RESET
RESET
11
10
01
00
BOD
V
has expired.
may be below nominal minimum operating voltage for some devices. For
CC
BOT+
given in Table 16.
in Figure 19), the delay counter starts the MCU after the Time-
BOT+
= V
CC
V
BOT
BOT-
(1)
Min V
ATmega325/3250/645/6450
decreases to a value below the trigger level (V
+ V
BOT
HYST
CC
if the voltage stays below the trigger level
/2 and V
Typ V
1.8
2.7
4.3
BOD Disabled
BOT-
BOT
Min
V
t
TOUT
BOT+
= V
BOT
Typ
50
Max V
2
- V
CC
CC
HYST
increases above
BOT
= V
Max
/2.
BOT
during the
CC
Units
Units
mV
V
µs
drops
BOT-
41