ATmega128A Atmel Corporation, ATmega128A Datasheet - Page 41

• Manufacturer Part Number: ATmega128A
• Manufacturer: Atmel Corporation

Specifications of ATmega128A

• Flash (kbytes): 128 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: 53
• Ext Interrupts: 8
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• 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): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 4
• Output Compare Channels: 8
• Input Capture Channels: 2
• Pwm Channels: 7
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

8.5
8.6
8151H–AVR–02/11
Low-frequency Crystal Oscillator
External RC Oscillator
Table 8-4.
Notes:
To use a 32.768 kHz watch crystal as the clock source for the device, the Low-frequency Crystal
Oscillator must be selected by setting the CKSEL fuses to “1001”. The crystal should be con-
nected as shown in
capacitors on XTAL1 and XTAL2, thereby removing the need for external capacitors. The inter-
nal capacitors have a nominal value of 36pF.
When this Oscillator is selected, start-up times are determined by the SUT fuses as shown in
Table
Table 8-5.
Note:
For timing insensitive applications, the External RC configuration shown in
used. The frequency is roughly estimated by the equation f = 1/(3RC). C should be at least
22pF. By programming the CKOPT fuse, the user can enable an internal 36 pF capacitor
between XTAL1 and GND, thereby removing the need for an external capacitor. For more infor-
mation on Oscillator operation and details on how to choose R and C, refer to the External RC
Oscillator application note.
CKSEL0
SUT1:0
00
01
10
11
1
1
1
8-5.
1. These options should only be used when not operating close to the maximum frequency of the
2. These options are intended for use with ceramic resonators and will ensure frequency stability
1. These options should only be used if frequency stability at start-up is not important for the
device, and only if frequency stability at start-up is not important for the application. These
options are not suitable for crystals.
at start-up. They can also be used with crystals when not operating close to the maximum fre-
quency of the device, and if frequency stability at start-up is not important for the application.
application.
SUT1:0
Start-up Times for the Crystal Oscillator Clock Selection (Continued)
Start-up Times for the Low-frequency Crystal Oscillator Clock Selection
Start-up Time from
Power-down and
01
10
11
Power-save
Figure
1K CK
1K CK
32K CK
Power-down and Power-
(1)
(1)
Start-up Time from
8-2. By programming the CKOPT fuse, the user can enable internal
16K CK
16K CK
16K CK
save
from Reset (V
Additional Delay
4.1ms
65ms
65ms
5.0V)
Reserved
from Reset (V
Additional Delay
CC
=
4.1ms
5.0V)
65ms
–
Recommended Usage
Fast rising power or BOD enabled
Slowly rising power
Stable frequency at start-up
CC
=
ATmega128A
Recommended Usage
Crystal Oscillator, BOD
enabled
Crystal Oscillator, fast
rising power
Crystal Oscillator, slowly
rising power
Figure 8-3
can be
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