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3. Frequency References
An external crystal is used for generating all radio frequencies and normal operation clocking. As an alternative, an external fre-
quency reference may be used. In addition, a low-power oscillator (LPO) is provided for lower power mode timing.
3.1 Crystal Interface and Clock Generation
The CYW43353 can use an external crystal to provide a frequency reference. The recommended configuration for the crystal oscil-
lator, including all external components, is shown in
ommended components.
A fractional-N synthesizer in the CYW43353 generates the radio frequencies, clocks, and data/packet timing, enabling the
CYW43353 to operate using a wide selection of frequency references.
For SDIO applications, the recommended default frequency reference is a 37.4 MHz crystal. The signal characteristics for the crystal
interface are listed in
Table
Note: Although the fractional-N synthesizer can support alternative reference frequencies, frequencies other than the default require
support to be added in the driver, plus additional extensive system testing. Contact Cypress for details.
Document Number: 002-14949 Rev. *G
PRELIMINARY
Figure
Figure 3. Recommended Oscillator Configuration
C *
C *
2.
3. Consult the reference schematics for the latest configuration and rec-
WRF_XTAL_IN
37.4 MHz
X ohms *
WRF_XTAL_OUT
*
Values determined by crystal drive
level. See reference schematics for details.
CYW43353
Page 14 of 113
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