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Electrical Specifications
X2/CLKIN
CLKOUT
Bypass Mode
NOTE A: The relationship of X2/CLKIN to CLKOUT depends on the PLL multiply and divide factor chosen for the CLKMD register. The waveform
relationship shown in Figure 5−3 is intended to illustrate the timing parameters based on CLKOUT = 1xCLKIN configuration.
5.6.5 Real-Time Clock Oscillator With External Crystal
The real-time clock module includes an oscillator circuit. The oscillator requires an external 32.768-kHz crystal
connected across the RTCINX1 and RTCINX2 pins. The connection of the required circuit, consisting of the
crystal and two load capacitors, is shown in Figure 5−5. The load capacitors, C
such that the equation below is satisfied. C
Figure 5−5. Real-Time Clock Oscillator With External Crystal
NOTE: The RTC can be idled by not supplying its 32-kHz oscillator signal. In order to keep
RTC power dissipation to a minimum when the RTC module is not used, it is recommended
that the RTC module be powered up, the RTC input pin (RTCINX1) be pulled low, and the RTC
output pin (RTCINX2) be left floating.
80
SPRS163H
C1
C12
C4
Figure 5−4. External Multiply-by-N Clock Timings
in the equation is the load specified for the crystal.
L
+
C
L
(C
RTCINX1
Crystal
32.768 kHz
C1
C2
C3
C3
C10
C11
C9
C8
C6
C
C
1
2
) C
)
1
2
RTCINX2
C2
C7
and C
, should be chosen
1
2
April 2001 − Revised January 2008
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