Si5345-44-42-D-RM
66
Rev. 1.0
11.3. Recommended Oscillators
Table 39 lists recommended TCXO suppliers.
11.4. Register Settings to Control External XTAL Reference
The following registers can be used to control and make adjustments for the external reference source used.
11.4.1. XAXB_FREQ_OFFSET Frequency Offset Register
The VCO locks to the XO that is formed by the crystal or XO and the XAXB pins. XAXB_FREQ_OFFSET provides
a static frequency offset to the VCO frequency. It is a 32-bit 2's complement number. This register can be used to
adjust the frequency of the VCO when it is locked to the XAXB frequency. The Default value is 0.
11.4.2. XAXB_EXTCLK_EN Reference Clock Selection Register
This bit selects between XTAL or external REFCLK on the XA/XB pins. Set this bit to use the external REFCLK.
Table 39. Recommended Oscillator Suppliers
Supplier
Part Number
TCXO/
OCXO
Frequency
Case
Size (mm x mm x mm)
Epson
TG-5500CA-68N-
49.1520000MHz
TCXO
49.152 MHz
5x7
Epson
TG-5500-67N-40.00000MHz
TCXO
40 MHz
5x7
Rakon
513872 (40MHz RTX7050A
HCMOS)
TCXO
40.000
5x7
NDK
NT7050BB-40.000M-
ENA4199B
TCXO
40.000
5x7
Vectron
VT-803-EAH-2870-40M0000
TCXO
40.000
5x3.2
Vectron
VT-803-EAH-2870-49M1520
TCXO
49.152
5x3.2
Vectron
VT-803-EAH-2870-50M0000
TCXO
50.000
5x3.2
Table 40. XAXB Frequency Offset Register
Register Name
Hex
Address
[Bit Field]
Function
XAXB_FREQ_OFFSET
0202[7:0]-
0205[7:0]
32-bit number which allows adjustment to the center frequency of the
XTAL in the range of ±1000 ppm.
Table 41. XAXB External Clock Selection Register
Register Name
Hex
Address
[Bit Field]
Function
XAXB_EXTCLK_EN
090E[0]
This bit selects between the XTAL or external REFCLK on the XA/XB pins.
The default is XTAL = 0