Datasheet

CC3200
WLAN_XTAL_P
WLAN_XTAL_N
XO (40MHz)
82 pF
TCXO_EN
EN
OUT
Vcc
SWAS031-087
SWAS031-030
WLAN_XTAL_P
WLAN_XTAL_N
23
22
40 MHz
GND
GND
6.2 pF
6.2 pF
CC3100
SWAS031D –JUNE 2013–REVISED FEBRUARY 2015 www.ti.com
Figure 4-11. Fast Clock Crystal Connections
4.11.3.4 Fast Clock (F
ref
) Using an External Oscillator
The CC3100 device can accept an external TCXO/XO for the 40-MHz clock. In this mode of operation, the clock
is connected to WLAN_XTAL_P (pin 23). WLAN_XTAL_N (pin 22) is connected to GND. The external TCXO/XO
can be enabled by TCXO_EN (pin 21) from the device to optimize the power consumption of the system.
If the TCXO does not have an enable input, an external LDO with an enable function can be used. Using the
LDO improves noise on the TCXO power supply.
Figure 4-12 shows the connection.
Figure 4-12. External TCXO Input
Table 4-5 lists the external F
ref
clock requirements.
Table 4-5. External F
ref
Clock Requirements (–40°C to +85°C)
Characteristics Condition Sym Min Typ Max Unit
Frequency 40.00 MHz
Frequency accuracy (Initial + temp + aging) ±25 ppm
Frequency input duty cycle 45 50 55 %
Clock voltage limits Sine or clipped Vpp 0.7 1.2 Vpp
sine wave, AC
coupled
Phase noise @ 40 MHz @ 1 kHz –125 dBc/Hz
@ 10 kHz –138.5 dBc/Hz
@ 100 kHz –143 dBc/Hz
Input impedance Resistance 12 KΩ
Capacitance 7 pF
18 Specifications Copyright © 2013–2015, Texas Instruments Incorporated
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