Datasheet

906
32142D–06/2013
ATUC64/128/256L3/4U
can be found in the crystal datasheet. The capacitance of the external capacitors (C
LEXT
) can
then be computed as follows:
where C
PCB
is the capacitance of the PCB and C
i
is the internal equivalent load capacitance.
Notes: 1. Please refer to the SCIF chapter for details.
2. Nominal crystal cycles.
3. These values are based on simulation and characterization of other AVR microcontrollers manufactured in the same pro-
cess technology. These values are not covered by test limits in production.
Figure 35-3. Oscillator Connection
C
LEXT
2C
L
C
i
–C
PCB
–=
Table 35-11. Crystal Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
f
OUT
Crystal oscillator frequency
(3)
0.45 10 16 MHz
C
L
Crystal load capacitance
(3)
618
pF
C
i
Internal equivalent load capacitance 2
t
STARTUP
Startup time SCIF.OSCCTRL.GAIN = 2
(1)
30 000
(2)
cycles
I
OSC
Current consumption
Active mode, f = 0.45MHz,
SCIF.OSCCTRL.GAIN = 0
30
µA
Active mode, f = 10MHz,
SCIF.OSCCTRL.GAIN = 2
220
XIN
XOUT
C
LEXT
C
LEXT
C
L
C
i
UC3L