ATMEGA649A-AU Atmel, ATMEGA649A-AU Datasheet - Page 32

• Manufacturer Part Number: ATMEGA649A-AU
• Description: IC MCU AVR 64K FLASH 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA649A-AU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 54
• 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
• Processor Series: ATmega
• Core: AVR
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: SPI, USART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 54
• Number Of Timers: 3
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Operating Temperature Range: - 40 C to + 85 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8.4
8.5
8284A–AVR–10/10
Calibrated Internal RC Oscillator
Crystal Oscillator
By default, the Internal RC Oscillator provides an approximate 8 MHz clock. Though voltage and
temperature dependent, this clock can be very accurately calibrated by the user. The device is
shipped with the CKDIV8 Fuse programmed. See
more details.
This clock may be selected as the system clock by programming the CKSEL Fuses as shown in
Table
the pre-programmed calibration value into the OSCCAL Register and thereby automatically cali-
brates the RC Oscillator. The accuracy of this calibration is shown as Factory calibration in
28-12 on page
By changing the OSCCAL register from SW, see
page
The accuracy of this calibration is shown as User calibration in
When this Oscillator is used as the chip clock, the Watchdog Oscillator will still be used for the
Watchdog Timer and for the Reset Time-out. For more information on the pre-programmed cali-
bration value, see the section
Table 8-3.
Notes:
When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in
Table
Table 8-4.
Note:
XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can be con-
figured for use as an On-chip Oscillator, as shown in
ceramic resonator may be used.
C1 and C2 should always be equal for both crystals and resonators. The optimal value of the
capacitors depends on the crystal or resonator in use, the amount of stray capacitance, and the
Power Conditions
BOD enabled
Fast rising power
Slowly rising power
ATmega169A/169PA/329A/329PA/649A/649P/3290A/3290PA/6490A/6490P
38, it is possible to get a higher calibration accuracy than by using the factory calibration.
8-3. If selected, it will operate with no external components. During reset, hardware loads
8-4.
1. The device is shipped with this option selected.
2. The frequency ranges are preliminary values.
3. If 8 MHz frequency exceeds the specification of the device (depends on V
1. The device is shipped with this option selected
Fuse can be programmed in order to divide the internal frequency by 8.
Internal Calibrated RC Oscillator Operating Modes
Start-up times for the internal calibrated RC Oscillator clock selection
353.
Frequency Range
7.3 - 8.1
Start-up Time from Power-
”Calibration Byte” on page
down and Power-save
(2)
(MHz)
Reserved
6 CK
6 CK
6 CK
”OSCCAL – Oscillator Calibration Register” on
”System Clock Prescaler” on page 37
.
Figure
314.
Additional Delay from
Reset (V
Table 28-12 on page
8-2. Either a quartz crystal or a
14CK + 65 ms
14CK + 4.1 ms
(1)(3)
14CK
CC
CKSEL3...0
= 5.0V)
0010
(1)
CC
), the CKDIV8
353.
SUT1...0
00
01
10
11
Table
for
32