CP3BT23_14 Datasheet, PDF (66/324 Pages) Texas Instruments – CP3BT23 Reprogrammable Connectivity Processor with Bluetooth and Dual CAN Interfaces

CP3BT23
SNOSCX3A – JULY 2013 – REVISED JANUARY 2014
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11.1 EXTERNAL CRYSTAL NETWORK
An external crystal network is connected to the X1CKI and X1CKO pins to generate the Main Clock,
unless an external clock signal is driven on the X1CKI pin. A similar external crystal network may be used
at pins X2CKI and X2CKO for the Slow Clock. If an external crystal network is not used for 12 MHz
Crystal X1CKI the Slow Clock, the Slow Clock is generated by dividing the fast Main Clock.
The crystal network you choose may require external components different from the ones specified in this
datasheet. In this case, consult with National’s engineers for the component specifications.
The crystals and other oscillator components must be placed close to the X1CKI/X1CKO and
X2CKI/X2CKO device input pins to keep the printed trace lengths to an absolute minimum.
Figure 11-2 shows the external crystal network for the X1CKI and X1CKO pins. Figure 11-3 shows the
external crystal network for the X2CKI and X2CKO pins. Table 11-1 shows the component specifications
for the main crystal network, and Table 11-1 shows the component specifications for the 32.768 kHz
crystal network.
12 MHz
Crystal
X1CKI
C1
X1CKO
C2
GND
DS189
Figure 11-2. Main Clock External Crystal Network
X2CKI
C1
32.768 kHz
Crystal
X2CKO
C2
GND
DS215
Figure 11-3. Slow Clock External Crystal Network
66
Triple Clock and Reset
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