CC3100_15 Datasheet, PDF (18/44 Pages) Texas Instruments – CC3100 SimpleLink Wi-Fi Network Processor, Internet-of-Things Solution for MCU Applications

CC3100
SWAS031D – JUNE 2013 – REVISED FEBRUARY 2015
23
WLAN_XTAL_P
40 MHz
6.2 pF
GND
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WLAN_XTAL_N ²²
6.2 pF
GND
SWAS031-030
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.
CC3200
TCXO_EN
WLAN_XTAL_P
82 pF
Vcc
XO (40MHz)
EN
OUT
WLAN_XTAL_N
SWAS031-087
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
Frequency
Frequency accuracy (Initial + temp + aging)
Frequency input duty cycle
Clock voltage limits
Phase noise @ 40 MHz
Input impedance
Resistance
Capacitance
Condition
Sine or clipped
sine wave, AC
coupled
@ 1 kHz
@ 10 kHz
@ 100 kHz
Sym
Vpp
Min
Typ
40.00
45
50
0.7
12
Max
Unit
MHz
±25
ppm
55
%
1.2
Vpp
–125
–138.5
–143
7
dBc/Hz
dBc/Hz
dBc/Hz
KΩ
pF
18
Specifications
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