CP3BT26G18NEP/HAPB National Semiconductor, CP3BT26G18NEP/HAPB Datasheet - Page 52

• Manufacturer Part Number: CP3BT26G18NEP/HAPB
• Manufacturer: National Semiconductor

Specifications of CP3BT26G18NEP/HAPB

• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 128
• Package Type: LQFP
• Lead Free Status / RoHS Status: Not Compliant

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11.1
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
the Slow Clock, the Slow Clock is generated by dividing the
fast Main Clock.
The crystal network you choose may require external com-
ponents different from the ones specified in this datasheet.
In this case, consult with National’s engineers for the com-
ponent specifications
The crystals and other oscillator components must be
placed close to the X1CKI/X1CKO and X2CKI/X2CKO de-
vice input pins to keep the printed trace lengths to an abso-
lute minimum.
Figure 5 shows the external crystal network for the X1CKI
and X1CKO pins. Figure 6 shows the external crystal net-
work for the X2CKI and X2CKO pins. Table 21 shows the
component specifications for the main crystal network, and
Table 22 shows the component specifications for the 32.768
kHz crystal network.
Crystal
Capacitor C1, C2
Component
EXTERNAL CRYSTAL NETWORK
Table 21 Component Values of the High Frequency Crystal Circuit
Resonance Frequency
Type
Max. Serial Resistance
Max. Shunt Capacitance
Load Capacitance
Capacitance
Parameters
52
Figure 5. Main Clock External Crystal Network
Figure 6. Slow Clock External Crystal Network
12 MHz ± 20 ppm
Values
AT-Cut
22 pF
22 pF
50
7 pF
Tolerance
20%
N/A