Datasheet

117
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
16.4 Clock Characteristics
16.4.1 Accuracy of Calibrated Internal Oscillator
It is possible to manually calibrate the internal oscillator to be more accurate than default factory calibration. Note
that the oscillator frequency depends on temperature and voltage. Voltage and temperature characteristics can be
found in Figure 17-39 on page 141 and Figure 17-40 on page 141.
Notes: 1. Accuracy of oscillator frequency at calibration point (fixed temperature and fixed voltage).
16.4.2 External Clock Drive
Figure 16-2. External Clock Drive Waveform
Table 16-2. Calibration Accuracy of Internal RC Oscillator
Calibration
Method Target Frequency V
CC
Temperature
Accuracy at given Voltage
& Temperature
(1)
Factory
Calibration
8.0 MHz 3V 25C±10%
User
Calibration
Fixed frequency within:
7.3 – 8.1 MHz
Fixed voltage within:
1.8V – 5.5V
Fixed temp. within:
-40C – 85C
±1%
V
IL1
V
IH1
Table 16-3. External Clock Drive Characteristics
Symbol Parameter
V
CC
= 1.8 - 5.5V V
CC
= 2.7 - 5.5V V
CC
= 4.5 - 5.5V
UnitsMin. Max. Min. Max. Min. Max.
1/t
CLCL
Clock Frequency 0 4 0 8 0 12 MHz
t
CLCL
Clock Period 250 125 83 ns
t
CHCX
High Time 100 50 33 ns
t
CLCX
Low Time 100 50 33 ns
t
CLCH
Rise Time 2.0 1 0.6 s
t
CHCL
Fall Time 2.0 1 0.6 s
t
CLCL
Change in period from one clock cycle to the next 2 2 2 %