ATmega3250A Atmel Corporation, ATmega3250A Datasheet - Page 32

• Manufacturer Part Number: ATmega3250A
• Manufacturer: Atmel Corporation

Specifications of ATmega3250A

• Flash (kbytes): 32 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 69
• Ext Interrupts: 25
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• 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): 2
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• 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: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

9.5
8285D–AVR–06/11
Crystal Oscillator
ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P
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
electromagnetic noise of the environment. Some initial guidelines for choosing capacitors for
use with crystals are given in
the manufacturer should be used.
Figure 9-2.
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 9-5.
Notes:
The CKSEL0 Fuse together with the SUT1:0 Fuses select the start-up times as shown in
9-6.
Table 9-6.
CKSEL0
CKSEL3:1
100
0
0
0
101
110
111
(1)
1. This option should not be used with crystals, only with ceramic resonators.
SUT1:0
Crystal Oscillator Connections
Crystal Oscillator Operating Modes
Start-up Times for the Crystal Oscillator Clock Selection
00
01
10
Frequency Range (MHz)
Start-up Time from
Power-down and
0.4 - 0.9
0.9 - 3.0
3.0 - 8.0
Power-save
8.0 -
Table
258 CK
258 CK
1K CK
C2
C1
9-5. For ceramic resonators, the capacitor values given by
(2)
(1)
(1)
Additional Delay
Recommended Range for Capacitors C1 and
14CK + 4.1ms
14CK + 65ms
(V
XTAL2 (TOSC2)
XTAL1 (TOSC1)
GND
from Reset
CC
14CK
Figure
= 5.0V)
C2 for Use with Crystals (pF)
9-2. Either a quartz crystal or a
12 - 22
12 - 22
12 - 22
Recommended Usage
Ceramic resonator, fast
rising power
Ceramic resonator, slowly
rising power
Ceramic resonator, BOD
enabled
–
Table
9-5.
Table
32