ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 50

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

11.5
11.6
50
Brown-out Detection
Watchdog System Reset
Atmel ATmega48PA/88PA/168PA [Preliminary]
The Atmel
monitoring the V
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
and V
Brown-out Reset is immediately activated. When V
in
has expired.
The BOD circuit will only detect a drop in V
ger than t
Figure 11-5. Brown-out Reset During Operation
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
Refer to
Figure 11-6. Watchdog System Reset During Operation
Figure 11-5 on page
CC
CC
page 51
decreases to a value below the trigger level (V
BOD
®
ATmega48PA/88PA/168PA has an On-chip Brown-out Detection (BOD) circuit for
INTERNAL
TIME-OUT
given in
RESET
RESET
BOT+
CC
V
for details on operation of the Watchdog Timer.
CC
level during operation by comparing it to a fixed trigger level. The trigger
= V
“System and Reset Characteristics” on page
50), the delay counter starts the MCU after the Time-out period t
BOT
+ V
HYST
/2 and V
V
CK
BOT-
CC
BOT-
if the voltage stays below the trigger level for lon-
= V
CC
BOT
increases above the trigger level (V
– V
BOT-
HYST
V
in
t
TOUT
BOT+
Figure 11-5 on page
/2.When the BOD is enabled,
318.
9223B–AVR–09/11
50), the
TOUT
TOUT
BOT+
.