ATmega325 Atmel Corporation, ATmega325 Datasheet - Page 43

• Manufacturer Part Number: ATmega325
• Manufacturer: Atmel Corporation

Specifications of ATmega325

• Flash (kbytes): 32 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 54
• Ext Interrupts: 17
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 2
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

11.4
11.5
2570N–AVR–05/11
External Reset
Brown-out Detection
Figure 11-3. 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
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
delay counter starts the MCU after the Time-out period – t
Figure 11-4. External Reset During Operation
Atmel ATmega325/3250/645/6450 has an On-chip Brown-out Detection (BOD) circuit for moni-
toring the V
the BOD can be selected by the BODLEVEL Fuses. The trigger level has a hysteresis to ensure
spike free Brown-out Detection. The hysteresis on the detection level should be interpreted as
V
decreases to a value below the trigger level (V
Reset is immediately activated. When V
5 on page
The BOD circuit will only detect a drop in V
ger than t
BOT+
INTERNAL
TIME-OUT
= V
RESET
RESET
BOD
V
BOT
44), the delay counter starts the MCU after the Time-out period t
CC
CC
CC
given in
level during operation by comparing it to a fixed trigger level. The trigger level for
+ V
HYST
“System and Reset Characteristics” on page
/2 and V
V
“System and Reset Characteristics” on page
POT
BOT-
= V
CC
BOT
increases above the trigger level (V
CC
ATmega325/3250/645/6450
- V
if the voltage stays below the trigger level for lon-
V
BOT-
RST
HYST
t
TOUT
in
/2. When the BOD is enabled, and V
Figure 11-5 on page
TOUT
– has expired.
RST
301.
– on its positive edge, the
TOUT
301) will generate a
44), the Brown-out
BOT+
has expired.
in
Figure 11-
43
CC