ATmega406 Atmel Corporation, ATmega406 Datasheet - Page 27

• Manufacturer Part Number: ATmega406
• Manufacturer: Atmel Corporation

Specifications of ATmega406

• Flash (kbytes): 40 Kbytes
• Pin Count: 48
• Max. Operating Frequency: 1 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 18
• Ext Interrupts: 4
• Usb Speed: No
• Usb Interface: No
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 12
• Adc Speed (ksps): 1.9
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 2
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -30 to 85
• I/o Supply Class: 4.0 to 25
• Operating Voltage (vcc): 4.0 to 25
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 3
• Pwm Channels: 2
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

7.4
7.5
7.6
7.7
2548E–AVR–07/06
32 kHz Crystal Oscillator
Slow RC Oscillator
Ultra Low Power RC Oscillator
CPU, I/O, Flash, and Voltage ADC Clock
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
use with a 32.768 kHz watch crystal.
C1 and C2 should always be equal. 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 envi-
ronment. For information on how to choose capacitors and other details on Oscillator operation,
refer to the 32 kHz Crystal Oscillator application note.
Figure 7-2.
The Slow RC Oscillator provides a fixed 131 kHz clock. This clock source can be used as a
backup clock source in case of 32 kHz Crystal Oscillator failure. It can also be used as the only
Run-Time clock source in systems where the resulting clock accuracy is acceptable. To provide
good accuracy when used as a Run-Time clock source, the slow RC Oscillator has a calibration
byte stored in the signature address space. See the section
order to get the actual timeout periods, the application software must use this calibration byte to
scale the WUT time-outs found in
The Ultra Low Power RC Oscillator (ULP Oscillator) provides a clock of 128 kHz. It operates at
very low power consumption, at the expense of frequency accuracy.
The clock source for the CPU, I/O, Flash, and Voltage ADC is the calibrated Fast RC Oscillator.
Note that the Calibrated Fast RC Oscillator will provide a 4 MHz clock to the TWI module and a
1 MHz clock to all other modules.
When the CPU wakes up from Power-down or Power-save, the CPU clock source is used to
time the start-up, ensuring a stable clock before instruction execution starts. When the CPU
starts from reset, there is an additional delay allowing the voltage regulator to reach a stable
level before commencing normal operation. The Ultra Low Power RC Oscillator is used for tim-
ing this real-time part of the start-up time. Start-up times are determined by the SUT Fuses as
32 kHz Crystal Oscillator Connections
Table 10-1 on page
C2
C1
Figure
50.
XTAL2
XTAL1
GND
”Calibration Bytes” on page
7-2. This Oscillator is optimized for
ATmega406
198. In
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