Datasheet

C
L
+
C
1
C
2
(C
1
) C
2
)
TMS320C28346, TMS320C28345, TMS320C28344
TMS320C28343, TMS320C28342, TMS320C28341
SPRS516D –MARCH 2009–REVISED AUGUST 2012 www.ti.com
3.6.1.1 External Reference Oscillator Clock Option
The on-chip oscillator requires an external crystal to be connected across the X1 and X2 pins.
The connection of the required circuit, consisting of the crystal and two load capacitors, is shown in
Figure 3-12. The load capacitors, C
1
and C
2
, must be chosen such that the equation below is satisfied
(typical values are on the order of C1 = C2 = 10 pF). C
L
in the equation is the load specified for the
crystal. All discrete components used to implement the oscillator circuit must be placed as close as
possible to the associated oscillator pins (X1, X2, and V
SSK
).
NOTE
The external crystal load capacitors must be connected only to the oscillator ground pin
(V
SSK
). Do not connect to board ground (V
SS
).
Where: C
L
equals the crystal load capacitance.
TI recommends that customers have the crystal vendor characterize the operation of their device with the
MCU chip. The crystal vendor has the equipment and expertise to tune the crystal circuit. The vendor can
also advise the customer regarding the proper component values that will produce proper start up and
stability over the entire operating range.
56 Functional Overview Copyright © 2009–2012, Texas Instruments Incorporated
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