cp2200 Silicon Laboratories, cp2200 Datasheet - Page 19

• Manufacturer Part Number: cp2200
• Description: Single-chip Ethernet Controller
• Manufacturer: Silicon Laboratories

6.4. Clocking Options
The CP2200/1 can be clocked from an external parallel-mode crystal oscillator or CMOS clock. Figure 10 and
Figure 11 show typical connections for both clock source types. If a crystal oscillator is chosen to clock the device,
the crystal is started once the device is released from reset and remains on until the device reenters the reset state
or loses power.
Important note on external crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The crystal
should be placed as close as possible to the XTAL pins on the device. The traces should be as short as possible
and shielded with a ground plane from any other traces that could introduce noise or interference.
Table 7 lists the clocking requirements of the CP2200/1 when using a crystal oscillator or CMOS clock. Table 8
shows the electrical characteristics of the XTAL1 pin. These characteristics are useful when selecting an external
CMOS clock.
20 MHz
CMOS
Clock
Figure 11. External CMOS Clock Example
Figure 10. Crystal Oscillator Example
20 MHz
Rev. 1.0
10 MΩ
No Connect
XTAL1
XTAL2
XTAL1
XTAL2
CP2200/1
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