ATMEGA128-16AU SL383 Atmel, ATMEGA128-16AU SL383 Datasheet - Page 52

• Manufacturer Part Number: ATMEGA128-16AU SL383
• Manufacturer: Atmel

Power-on Reset
External Reset
52
ATmega128
A Power-on Reset (POR) pulse is generated by an On-chip detection circuit. The detection level
is defined in
POR circuit can be used to trigger the Start-up Reset, as well as to detect a failure in supply
voltage.
A Power-on Reset (POR) circuit ensures that the device is reset from Power-on. Reaching the
Power-on Reset threshold voltage invokes the delay counter, which determines how long the
device is kept in RESET after V
when V
Figure 23. MCU Start-up, RESET Tied to V
Figure 24. MCU Start-up, RESET Extended Externally
An External Reset is generated by a low level on the RESET pin. Reset pulses longer than the
minimum pulse width (see
Shorter pulses are not guaranteed to generate a reset. When the applied signal reaches the
Reset Threshold Voltage – V
Time-out period t
CC
INTERNAL
INTERNAL
2. V
TIME-OUT
TIME-OUT
decreases below the detection level.
RESET
RESET
RESET
RESET
this is the case, the device is tested down to V
antees that a Brown-out Reset will occur before V
operation of the microcontroller is no longer guaranteed. The test is performed using
BODLEVEL=1for ATmega128L and BODLEVEL=0 for ATmega128. BODLEVEL=1 is not
applicable forATmega128
V
V
BOT
Table
CC
CC
may be below nominal minimum operating voltage for some devices. For devices where
TOUT
19. The POR is activated whenever V
has expired.
Table
RST
V
V
V
POT
POT
RST
CC
on its positive edge, the delay counter starts the MCU after the
t
rise. The RESET signal is activated again, without any delay,
TOUT
19) will generate a reset, even if the clock is not running.
CC
.
V
RST
t
TOUT
CC
= V
BOT
CC
CC
is below the detection level. The
during the production test. This guar-
drops to a voltage where correct
2467S–AVR–07/09