ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 40

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

External Reset
Brown-out Detection
40
ATmega325/3250/645/6450
Figure 16. MCU Start-up, RESET Tied to V
Figure 17. 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 Table 16) 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
counter starts the MCU after the Time-out period – t
Figure 18. External Reset During Operation
ATmega325/3250/645/6450 has an On-chip Brown-out Detection (BOD) circuit for mon-
itoring the V
level for the BOD can be selected by the BODLEVEL Fuses. The trigger level has a hys-
INTERNAL
INTERNAL
TIME-OUT
TIME-OUT
RESET
RESET
RESET
RESET
V
V
CC
CC
CC
CC
level during operation by comparing it to a fixed trigger level. The trigger
V
V
V
POT
POT
RST
t
TOUT
V
RST
CC
t
TOUT
RST
TOUT
– on its positive edge, the delay
– has expired.
2570A–AVR–09/04