Datasheet

52
8272E–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
Figure 11-2. MCU Start-up, RESET Tied to V
CC
.
Figure 11-3. MCU Start-up, RESET
Extended Externally.
11.1.3 External Reset
An External Reset is generated by a low level on the RESET
pin. Reset pulses longer than the
minimum pulse width (see ”” on page 337) will generate a 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
RST
– on its positive edge, the delay counter starts the MCU after
the Time-out period – t
TOUT
– has expired.
Figure 11-4. External Reset During Operation
V
RESET
TIME-OUT
INTERNAL
RESET
t
TOUT
V
POT
V
RST
CC
RESET
TIME-OUT
INTERNAL
RESET
t
TOUT
V
POT
V
RST
V
CC
CC