BCM4354 Data Sheet
External Frequency Reference
External Frequency Reference
For operation in SDIO and HSIC modes only, an alternative to a crystal (an external precision frequency
reference) can be used. The recommended default frequency is 52 MHz ±10 ppm, and it must meet the phase
noise requirements listed in Table 3.
If used, the external clock should be connected to the WRF_XTAL_IN pin through an external 1000 pF coupling
capacitor, as shown in Figure 5. The internal clock buffer connected to this pin will be turned OFF when the
BCM4354 goes into sleep mode. When the clock buffer turns ON and OFF there will be a small impedance
variation. Power must be supplied to the WRF_XTAL_VDD1P5 pin.
Figure 5: Recommended Circuit to Use with an External Reference Clock
1000 pF
Reference
WRF_XTAL_IN
Clock
NC
WRF_XTAL_OUT
Table 3: Crystal Oscillator and External Clock—Requirements and Performance
External Frequency
Crystala
Referenceb,c
Parameter
Conditions/Notes
Min. Typ. Max. Min. Typ. Max. Units
Frequency
2.4G and 5G bands: IEEE
802.11ac operation, SDIO3.0,
HSIC and PCIe WLAN
interfaces
35
37.4
–
–
52
–
MHz
2.4G and 5G bands, IEEE
802.11ac operation, PCIe
interface alternative frequency
–
40
–
–
–
–
–
–
MHz
MHz
5G band: IEEE 802.11n
operation only
19
52
35
52
Ranges between 19 MHz and 52 MHzd,e
2.4G band: IEEE 802.11n
operation, and both bands
legacy 802.11a/b/g operation
only
Frequency tolerance Without trimming
over the lifetime of the
–20
–
20
–20
–
20
ppm
equipment, including
temperaturef
Crystal load
capacitance
–
–
–
–
12
–
–
–
–
–
–
–
–
pF
ESR
60
Ω
Broadcom®
October 15, 2014 • 4354-DS109-R
Page 28
BROADCOM CONFIDENTIAL
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