ATMEGA128-16AI Atmel, ATMEGA128-16AI Datasheet - Page 38

• Manufacturer Part Number: ATMEGA128-16AI
• Description: IC AVR MCU 128K 16MHZ 64-TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA128-16AI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 128KB (64K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 4K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• For Use With: ATSTK501 - ADAPTER KIT FOR 64PIN AVR MCU
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: Q1167170A

Crystal Oscillator
38
ATmega128
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. The CKOPT fuse selects between two different Oscillator
Amplifier modes. When CKOPT is programmed, the Oscillator output will oscillate will a full rail-
to-rail swing on the output. This mode is suitable when operating in a very noisy environment or
when the output from XTAL2 drives a second clock buffer. This mode has a wide frequency
range. When CKOPT is unprogrammed, the Oscillator has a smaller output swing. This reduces
power consumption considerably. This mode has a limited frequency range and it can not be
used to drive other clock buffers.
For resonators, the maximum frequency is 8MHz with CKOPT unprogrammed and 16MHz with
CKOPT programmed. 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 electromagnetic noise of the environment. Some initial guidelines for
choosing capacitors for use with crystals are given in
capacitor values given by the manufacturer should be used.
Figure 19. Crystal Oscillator Connections
The Oscillator can operate in three different modes, each optimized for a specific frequency
range. The operating mode is selected by the fuses CKSEL3..1 as shown in
Table 8. Crystal Oscillator Operating Modes
Note:
The CKSEL0 fuse together with the SUT1..0 fuses select the start-up times as shown in
CKOPT
1
1
1
0
1. This option should not be used with crystals, only with ceramic resonators.
101, 110, 111
CKSEL3..1
101
110
111
(1)
Frequency Range
0.4 - 0.9
0.9 - 3.0
3.0 - 8.0
(MHz)
1.0 -
C2
C1
Recommended Range for Capacitors
C1 and C2 for Use with Crystals
Figure
Table
XTAL2
XTAL1
GND
12 - 22pF
12 - 22pF
12 - 22pF
19. Either a quartz crystal or a
8. For ceramic resonators, the
–
Table
2467V–AVR–02/11
8.
Table
9.