BCM43362KUBG Datasheet, PDF (20/84 Pages) Cypress Semiconductor – Single-Chip IEEE 802.11™ b/g/n MAC/Baseband/Radio + SDIO

BCM43362 Data Sheet
TCXO
TCXO
As an alternative to a crystal, an external precision TCXO can be used as the frequency reference, provided
that it meets the Phase Noise requirements listed in Table 2 on page 20. When the clock is provided by an
external TCXO, there are two possible connection methods, as shown in Figure 5 and Figure 6:
1. If the TCXO is dedicated to driving the BCM43362, it should be connected to the OSC_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 BCM43362 goes into sleep mode. When the clock buffer turns ON and OFF,
there will be a small impedance variation up to ±15%. Power must be supplied to the WRF_XTAL_VDD1P2
pin.
2. An alternative is to DC-couple the TCXO to the WRF_TCXO_IN pin, as shown in Figure 6. Use this method
when the same TCXO is shared with other devices and a change in the input impedance is not acceptable
because it may cause a frequency shift that cannot be tolerated by the other device sharing the TCXO. This
pin is connected to a clock buffer powered from WRF_TCXO_VDD3P3. If the power supply to this buffer is
always on (even in sleep mode), the clock buffer is always on, thereby ensuring a constant input impedance
in all states of the device. The maximum current drawn from WRF_TCXO_VDD3P3 is approximately
500 µA.
Figure 5: Recommended Circuit to Use with an External Dedicated TCXO
TCXO
1000 pF
NC
OSCIN
OSCOUT
WRF_TCXO_IN
WRF_TCXO_VDD3P3
Figure 6: Recommended Circuit to Use with an External Shared TCXO
TCXO
Connect to a supply (1.7V to 3.3V)
that is powered up or down with the
external TCXO clock.
To other devices
WRF_TCXO_IN
WRF_TCXO_VDD3P3
OSCIN
NC
OSCOUT
Broadcom_®
February 13, 2015 • 43362-DS106-R
IEEE 802.11 b/g/n MAC/Baseband/Radio + SDIO
Page 19
BROADCOM CONFIDENTIAL