ATtiny25 Automotive Atmel Corporation, ATtiny25 Automotive Datasheet - Page 26

• Manufacturer Part Number: ATtiny25 Automotive
• Manufacturer: Atmel Corporation

Specifications of ATtiny25 Automotive

• Flash (kbytes): 2 Kbytes
• Pin Count: 8
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 4
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 6
• Ext Interrupts: 6
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 4
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.12
• Eeprom (bytes): 128
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 125
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 5
• Pwm Channels: 6
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

6.6
6.6.1
26
Calibrated Internal RC Oscillator
ATtiny25/45/85
Oscillator Calibration Register – OSCCAL
The calibrated internal RC Oscillator provides an 8.0 MHz clock. The frequency is the nominal
value at 3V and 25°C. If the frequency exceeds the specification of the device (depends on V
the CKDIV8 Fuse must be programmed in order to divide the internal frequency by 8 during
start-up.
as the system clock by programming the CKSEL Fuses as shown in
operate with no external components. During reset, hardware loads the calibration byte into the
OSCCAL Register and thereby automatically calibrates the RC Oscillator. At 3V and 25°C, this
calibration gives a frequency within ± 1% of the nominal frequency. 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 calibration value, see the section
“Calibration Byte” on page
Table 6-6.
Note:
When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in
Table
Table 6-7.
Note:
• Bits 7..0 – CAL7..0: Oscillator Calibration Value
Writing the calibration byte to this address will trim the internal Oscillator to remove process vari-
ations from the Oscillator frequency. This is done automatically during Chip Reset. When
OSCCAL is zero, the lowest available frequency is chosen. Writing non-zero values to this regis-
ter will increase the frequency of the internal Oscillator. Writing 0xFF to the register gives the
highest available frequency. The calibrated Oscillator is used to time EEPROM and Flash
access. If EEPROM or Flash is written, do not calibrate to more than 8.8 MHz frequency. Other-
wise, the EEPROM or Flash write may fail.
Bit
Read/Write
Initial Value
SUT1..0
10
00
01
11
(1)
6-7.
1. The device is shipped with this option selected.
1. The device is shipped with this option selected.
See “System Clock Prescaler” on page 29.
CKSEL3..0
Internal Calibrated RC Oscillator Operating Modes
Start-up Times for the Internal Calibrated RC Oscillator Clock Selection
0010
CAL7
R/W
7
from Power-down
(1)
Start-up Time
6 CK
6 CK
6 CK
CAL6
R/W
6
137.
CAL5
R/W
5
Device Specific Calibration Value
CAL4
R/W
4
Additional Delay from
Reset (V
Reserved
14CK + 64 ms
14CK + 4 ms
14CK + 4 ms
CAL3
for more details. This clock may be selected
R/W
3
CC
Nominal Frequency
= 5.0V)
CAL2
R/W
8.0 MHz
2
Table
CAL1
R/W
Recommended Usage
BOD enabled
Fast rising power
Slowly rising power
1
6-6. If selected, it will
CAL0
R/W
0
7598H–AVR–07/09
OSCCAL
CC
),