ATMEGA649V-8AI Atmel, ATMEGA649V-8AI Datasheet - Page 43

• Manufacturer Part Number: ATMEGA649V-8AI
• Description: IC AVR MCU FLASH 64K 1.8V 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA649V-8AI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

10.4
10.5
2552K–AVR–04/11
External Reset
Brown-out Detection
Figure 10-3. 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 10-4. External Reset During Operation
ATmega329/3290/649/6490 has an On-chip Brown-out Detection (BOD) circuit for monitoring
the V
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
When the BOD is enabled, and V
10-5), the Brown-out Reset is immediately activated. When V
level (V
expired.
The BOD circuit will only detect a drop in V
ger than t
BOT+
INTERNAL
TIME-OUT
CC
= V
BOT+
RESET
RESET
level during operation by comparing it to a fixed trigger level. The trigger level for the
BOD
BOT
V
CC
CC
in
+ V
given in
Figure
HYST
/2 and V
10-5), the delay counter starts the MCU after the Time-out period t
“System and Reset Characteristics” on page
V
“System and Reset Characteristics” on page
POT
BOT-
CC
= V
decreases to a value below the trigger level (V
BOT
- V
CC
HYST
ATmega329/3290/649/6490
if the voltage stays below the trigger level for lon-
V
RST
/2.
t
TOUT
TOUT
– has expired.
CC
RST
increases above the trigger
330.
– on its positive edge, the
330) will generate a
BOT-
in
TOUT
Figure
has
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