
58
32117DS–AVR-01/12
AT32UC3C
Notes:
1. Please refer to the SCIF chapter for details.
7.6.2
32KHz Crystal Oscillator (OSC32K) Characteristics
7.6.2.1
Digital Clock Characteristics
The following table describes the characteristics for the oscillator when a digital clock is applied
on XIN32.
7.6.2.2
Crystal Oscillator Characteristics
Figure 7-2 and the equation above also applies to the 32 KHz oscillator connection. The user
must choose a crystal oscillator where the crystal load capacitance C
L is within the range given
in the table. The exact value of C
L can then be found in the crystal datasheet..
Table 7-8.
Crystal Oscillator Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
fOUT
Crystal oscillator frequency
0.4
20
MHz
C
i
Internal equivalent load capacitance
1.7
pF
tSTARTUP
Startup time
fOUT = 8MHz
975
us
f
OUT = 16MHz
1100
us
Table 7-9.
Digital 32KHz Clock Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Units
fCPXIN
XIN32 clock frequency
32.768
5000
KHz
t
CPXIN
XIN32 clock period
200
ns
tCHXIN
XIN32 clock high half-priod
0.4 x tCPXIN
0.6 x tCPXIN
ns
t
CLXIN
XIN32 clock low half-priod
0.4 x t
CPXIN
0.6 x t
CPXIN
ns
C
IN
XIN32 input capacitance
2
pF
Table 7-10.
32 KHz Crystal Oscillator Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
fOUT
Crystal oscillator frequency
32 768
Hz
t
STARTUP
Startup time
R
S = 50 kOhm, CL = 12.5 pF
2
s
C
L
Crystal load capacitance
6
15
pF
C
i
Internal equivalent load
capacitance
1.4
pF