ATmega644P Atmel Corporation, ATmega644P Datasheet - Page 53

• Manufacturer Part Number: ATmega644P
• Manufacturer: Atmel Corporation

Specifications of ATmega644P

• Flash (kbytes): 64 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 32
• Ext Interrupts: 32
• Usb Speed: No
• Usb Interface: No
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• 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): 4
• Eeprom (bytes): 2048
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• 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: 6
• Input Capture Channels: 1
• Pwm Channels: 6
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

8.5
8.6
8011O–AVR–07/10
Brown-out Detection
Watchdog Reset
ATmega164P/324P/644P has an On-chip Brown-out Detection (BOD) circuit for monitoring the
V
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
V
When the BOD is enabled, and V
8-5 on page
trigger level (V
out period t
The BOD circuit will only detect a drop in V
ger than t
Figure 8-5.
When the Watchdog times out, it will generate a short reset pulse of one CK cycle duration. On
the falling edge of this pulse, the delay timer starts counting the Time-out period t
page 61
Figure 8-6.
CC
BOT
level during operation by comparing it to a fixed trigger level. The trigger level for the BOD
+ V
for details on operation of the Watchdog Timer.
HYST
BOD
CC
TOUT
53), the Brown-out Reset is immediately activated. When V
/2 and V
given in
Brown-out Reset During Operation
Watchdog Reset During Operation
BOT+
INTERNAL
TIME-OUT
has expired.
RESET
RESET
in
V
CC
BOT-
Figure 8-5 on page
”System and Reset Characteristics” on page
= V
BOT
- V
CC
HYST
decreases to a value below the trigger level (V
V
CK
BOT-
/2.
53), the delay counter starts the MCU after the Time-
CC
if the voltage stays below the trigger level for lon-
ATmega164P/324P/644P
V
t
TOUT
BOT+
331.
CC
increases above the
TOUT
BOT-
. Refer to
in
Figure
BOT+
53
=