ATTINY25V-15ST Atmel, ATTINY25V-15ST Datasheet - Page 26

• Manufacturer Part Number: ATTINY25V-15ST
• Description: MCU AVR 2K FLASH 4MHZ 8-SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY25V-15ST

• Package / Case: 8-SOIC (3.9mm Width)
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Speed: 8MHz
• Number Of I /o: 6
• Eeprom Size: 128 x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 128 x 8
• Program Memory Size: 2KB (2K x 8)
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: USI
• Core Size: 8-Bit
• Processor Series: ATTINY2x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 128 B
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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
),