CYW20702
6.2 Crystal Oscillator
The CYW20702 can use an external crystal to provide a frequency reference. The recommended configuration for the crystal oscillator,
including all external components, is shown in Figure 7.
Figure 7. Recommended Oscillator Configuration
XIN
0 ~18 pF*
Crystal
Oscillator
XOUT
0 ~18 pF*
*Capacitor value range depends
on the manufacturer of the XTAL
as well as board layout.
6.3 External Frequency Reference
An external frequency reference, such as VDD_RF, collectively refers to several RF power supplies generated by a TCXO signal that
may be directly connected to the crystal input pin on the CYW20702, as shown in Figure 8. The external frequency reference input is
designed to not change loading on the TCXO when the CYW20702 is powered up or powered down.
When using the CYW20702 with the TXCO OR gate option, GPIO 6 must be driven active high or active low. Excessive leakage
current results if GPIO6 is allowed to float.
Figure 8. Recommended TCXO Connection
TCXO
XIN
10–1000 pF*
No Connection
XOUT
* Recommended value is 100 pF.
Higher values produce a longer startup time.
Lower values have greater isolation.
Larger values help small signal swings.
6.3.1 TCXO Clock Request Support
If the application utilizes an external TCXO as a clock reference, the CYW20702 provides a clock request output to allow the system
to power off the TCXO when not in use.
Document Number: 002-14773 Rev. *L
Page 24 of 55
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