Datasheet

724
32133D–11/2011
UC3D
Figure 32-2. Oscillator Connection
32.7.2 32KHz Crystal Oscillator (OSC32K) Characteristics
32.7.2.1 Digital Clock Characteristics
The following table describes the characteristics for the oscillator when a digital clock is applied
on XIN32.
Figure 32-2 and the equation above also applies to the 32KHz 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.
XIN
XOUT
C
LEXT
C
LEXT
C
L
C
i
UC3D
Table 32-12. Digital Clock Characteristics
Symbol Parameter Conditions Min Typ Max Units
f
CPXIN
XIN32 clock frequency 32.768 5000 KHz
t
CPXIN
XIN32 clock duty cycle 40 60 %
Table 32-13. 32 KHz Crystal Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
1/(t
CP32KHz
) Crystal oscillator frequency 32.768 5000 KHz
t
ST
Startup time R
S
= 50kOhm, C
L
= 9pF 2 s
C
L
Crystal load capacitance 6 15 pF
C
i
Internal equivalent load
capacitance
1.4 pF