ATmega325PA Atmel Corporation, ATmega325PA Datasheet - Page 47

• Manufacturer Part Number: ATmega325PA
• Manufacturer: Atmel Corporation

11.2.1
8285D–AVR–06/11
Power-on Reset
ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P
Figure 11-1. Reset Logic
A Power-on Reset (POR) pulse is generated by an On-chip detection circuit. The detection level
is defined in
V
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 11-2. MCU Start-up, RESET Tied to V
CC
is below the detection level. The POR circuit can be used to trigger the start-up Reset, as
INTERNAL
TIME-OUT
BODLEVEL [2..0]
CC
RESET
RESET
V
decreases below the detection level.
CC
”System and Reset Characteristics” on page
Pull-up Resistor
JTAG Reset
Register
FILTER
SPIKE
V
V
POT
RST
CC
t
TOUT
CKSEL[3:0]
rise. The RESET signal is activated again, without any delay,
Power-on Reset
Reset Circuit
SUT[1:0]
Brown-out
Watchdog
Oscillator
Generator
Circuit
Clock
CK
CC
Register (MCUSR)
MCU Status
DATA BUS
Delay Counters
326. The POR is activated whenever
TIMEOUT
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