AM335x
(ZCZ Package)
RTC_XTALIN
VSS_RTC
RTC_XTALOUT
C
1
C
2
Optional R
bias
Optional R
d
Crystal
AM335x
(ZCE Package)
RTC_XTALIN RTC_XTALOUT
C
1
C
2
Optional R
bias
Optional R
d
Crystal
AM3359, AM3358, AM3357, AM3356, AM3354, AM3352
www.ti.com
SPRS717H –OCTOBER 2011–REVISED MAY 2015
A. Oscillator components (Crystal, C
1
, C
2
, optional R
bias
and R
d
) must be located close to the AM335x package.
Parasitic capacitance to the printed circuit board (PCB) ground and other signals should be minimized to reduce noise
coupled into the oscillator. VSS_RTC and respective crystal circuit component grounds should be connected directly
to the nearest PCB digital ground (VSS).
B. C
1
and C
2
represent the total capacitance of the respective PCB trace, load capacitor, and other components
(excluding the crystal) connected to each crystal terminal. The value of capacitors C
1
and C
2
should be selected to
provide the total load capacitance, C
L
, specified by the crystal manufacturer. The total load capacitance is C
L
= [(C
1
×
C
2
) / (C
1
+ C
2
)] + C
shunt
, where C
shunt
is the crystal shunt capacitance (C
0
) specified by the crystal manufacturer plus
any mutual capacitance (C
pkg
+ C
PCB
) seen across the AM335x RTC_XTALIN and RTC_XTALOUT signals. For
recommended values of crystal circuit components, see Table 6-5.
Figure 6-12. OSC1 (ZCE Package) Crystal Circuit Schematic
A. Oscillator components (Crystal, C
1
, C
2
, optional R
bias
and R
d
) must be located close to the AM335x package.
Parasitic capacitance to the printed circuit board (PCB) ground and other signals should be minimized to reduce noise
coupled into the oscillator. VSS_RTC and respective crystal circuit component grounds should be connected directly
to the nearest PCB digital ground (VSS).
B. C
1
and C
2
represent the total capacitance of the respective PCB trace, load capacitor, and other components
(excluding the crystal) connected to each crystal terminal. The value of capacitors C
1
and C
2
should be selected to
provide the total load capacitance, C
L
, specified by the crystal manufacturer. The total load capacitance is C
L
= [(C
1
×
C
2
) / (C
1
+ C
2
)] + C
shunt
, where C
shunt
is the crystal shunt capacitance (C
0
) specified by the crystal manufacturer plus
any mutual capacitance (C
pkg
+ C
PCB
) seen across the AM335x RTC_XTALIN and RTC_XTALOUT signals. For
recommended values of crystal circuit components, see Table 6-5.
Figure 6-13. OSC1 (ZCZ Package) Crystal Circuit Schematic
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