atmega161-4pi ATMEL Corporation, atmega161-4pi Datasheet - Page 27

• Manufacturer Part Number: atmega161-4pi
• Description: 8-bit Microcontroller With 16k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Power-on Reset
1228D–AVR–02/07
A Power-on Reset (POR) pulse is generated by an On-chip detection circuit. The detec-
tion level is nominally 1.4V (rising V
the detection level. The POR circuit can be used to trigger the Start-up Reset, as well as
detect a failure in supply voltage.
A Power-on Reset (POR) circuit ensures that the device is reset from Power-on. Reach-
ing the Power-on Reset threshold voltage invokes a delay counter, which determines
the delay, for which the device is kept in RESET after V
the delay counter can be defined by the user through the CKSEL fuses. The eight differ-
ent selections for the delay period are presented in Table 4. The RESET signal is
activated again, without any delay, when the V
Figure 25. MCU Start-up, RESET Tied to V
Figure 26. MCU Start-up, RESET Controlled Externally
INTERNAL
INTERNAL
TIME-OUT
TIME-OUT
RESET
RESET
RESET
RESET
VCC
VCC
V
V
V
POT
POT
RST
t
TOUT
CC
). The POR is activated whenever V
V
RST
CC
CC
t
TOUT
decreases below detection level.
CC
ATmega161(L)
rise. The time-out period of
CC
is below
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