ATMEGA48V_06 ATMEL [ATMEL Corporation], ATMEGA48V_06 Datasheet - Page 47

• Manufacturer Part Number: ATMEGA48V_06
• Description: 8-bit Microcontroller with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

9.4
9.5
2545J–AVR–12/06
External Reset
Brown-out Detection
Figure 9-3.
An External Reset is generated by a low level on the RESET pin. Reset pulses longer than the
minimum pulse width (see
reset, even if the clock is not running. Shorter pulses are not guaranteed to generate a reset.
When the applied signal reaches the Reset Threshold Voltage – V
delay counter starts the MCU after the Time-out period – t
can be disabled by the RSTDISBL fuse, see
Figure 9-4.
ATmega48/88/168 has an On-chip Brown-out Detection (BOD) circuit for monitoring the V
level 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
value below the trigger level (V
When V
MCU after the Time-out period t
The BOD circuit will only detect a drop in V
longer than t
BOT
INTERNAL
TIME-OUT
+ V
RESET
CC
RESET
HYST
V
CC
increases above the trigger level (V
CC
BOD
/2 and V
MCU Start-up, RESET Extended Externally
External Reset During Operation
given in
BOT-
”System and Reset Characteristics” on page
= V
V
”System and Reset Characteristics” on page
POT
BOT
BOT-
TOUT
- V
in
has expired.
HYST
Figure
/2.When the BOD is enabled, and V
Table 26-6 on page
9-5), the Brown-out Reset is immediately activated.
CC
V
BOT+
RST
if the voltage stays below the trigger level for
t
TOUT
in
Figure
TOUT
ATmega48/88/168
– has expired. The External Reset
9-5), the delay counter starts the
287.
RST
– on its positive edge, the
307.
307) will generate a
CC
decreases to a
BOT+
47
CC
=