CYW4343X
Figure 16. Recommended Circuit to Use with an External Dedicated TCXO
200 pF – 1000 pF
TCXO
WLRF_XTAL_XOP
WLRF_XTAL_XON
NC
Table 3. Crystal Oscillator and External Clock Requirements and Performance
External Frequency
Reference
Crystal
Min. Typ.
Parameter
Conditions/Notes
Max.
Min. Typ. Max.
Units
37.4a
Frequency
–
–
–
–
–
–
MHz
Crystal load capacitance
ESR
–
–
–
–
12
–
–
–
–
–
–
–
–
–
–
–
pF
Ω
60
–
Drive level
External crystal must be able to tolerate 200
this drive level.
–
μW
Input Impedance
Resistive
–
–
–
–
–
–
–
–
–
10k
–
100k
–
7
Ω
(WLRF_XTAL_XOP)
Capacitive
–
–
pF
400b
WLRF_XTAL_XOP input
voltage
AC-coupled analog signal
1260
mVp-p
WLRF_XTAL_XOP input
low level
DC-coupled digital signal
–
–
–
–
–
0
–
–
–
0.2
V
WLRF_XTAL_XOP input
high level
DC-coupled digital signal
–
–
–
1.0
1.26
20
V
Frequency tolerance
Initial + over temperature
–20
20
–20
ppm
Duty cycle
37.4 MHz clock
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
40
–
50
–
60
%
Phase Noisec, d, e
(IEEE 802.11 b/g)
37.4 MHz clock at 10 kHz offset
37.4 MHz clock at 100 kHz offset
37.4 MHz clock at 10 kHz offset
37.4 MHz clock at 100 kHz offset
37.4 MHz clock at 10 kHz offset
37.4 MHz clock at 100 kHz offset
–129
–136
–134
–141
–140
–147
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
–
–
Phase Noisec, d, e
(IEEE 802.11n, 2.4 GHz)
–
–
–
–
Phase Noisec, d, e
(256-QAM)
–
–
–
–
a. The frequency step size is approximately 80 Hz. The CYW4343X does not auto-detect the reference clock frequency; the frequency is specified
in the software and/or NVRAM file.
b. To use 256-QAM, a 800 mV minimum voltage is required.
c. For a clock reference other than 37.4 MHz, 20 × log10(f/37.4) dB should be added to the limits, where f = the reference clock frequency in MHz.
d. Phase noise is assumed flat above 100 kHz.
e. The CYW4343X supports a 26 MHz reference clock sharing option. See the phase noise requirement in the table.
3.3 External 32.768 kHz Low-Power Oscillator
The CYW4343X uses a secondary low-frequency sleep clock for low-power mode timing. Either the internal low-precision LPO or an
external 32.768 kHz precision oscillator is required. The internal LPO frequency range is approximately 33 kHz ± 30% over process,
voltage, and temperature, which is adequate for some applications. However, one trade-off caused by this wide LPO tolerance is a
small current consumption increase during power save mode that is incurred by the need to wake up earlier to avoid missing bea-
cons.
Document No. 002-14797 Rev. *H
Page 23 of 128
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