16.9 Page 9 Registers Si5397C/D
Table 16.283. 0x090E XAXB Configuration
Reg Address
Bit Field
Type
Setting Name
Description
0x090E
0
R/W
XAXB_EXTCLK_EN Selects between the XTAL or external reference clock
on the XA/XB pins. Default is 0, XTAL. Set to 1 to use
an external reference oscillator.
Table 16.284. 0x0943 Control I/O Voltage Select
Reg Address
Bit Field
Type
Setting Name
Description
0x0943
0
R/W
IO_VDD_SEL
0: For 1.8 V external connections
1: For 3.3 V external connections
The IO_VDD_SEL configuration bit selects between 1.8 V and 3.3 V digital I/O. All digital I/O pins, including the serial interface pins, are
3.3 V tolerant. Setting this to the default 1.8 V is the safe default choice that allows writes to the device regardless of the serial interface
used or the host supply voltage. When the I2C or SPI host is operating at 3.3 V and the Si5397/96 at VDD=1.8 V, the host must write
IO_VDD_SEL=1. This will ensure that both the host and the serial interface are operating with the optimum signal thresholds.
Table 16.285. 0x0949 Clock Input Control and Configuration
Reg Address
Bit Field
Type
Setting Name
Description
0x0949
3:0
R/W
IN_EN
0: Disable and Powerdown Input Buffer
1: Enable Input Buffer
for IN3–IN0.
0x0949
7:4
R/W
IN_PULSED_CMO
S_EN
0: Standard Input Format
1: Pulsed CMOS Input Format for IN3–IN0. See for
more information.
When a clock is disabled, it is powered down.
Input 0 corresponds to IN_EN 0x0949 [0], IN_PULSED_CMOS_EN 0x0949 [4]
Input 1 corresponds to IN_EN 0x0949 [1], IN_PULSED_CMOS_EN 0x0949 [5]
Input 2 corresponds to IN_EN 0x0949 [2], IN_PULSED_CMOS_EN 0x0949 [6]
Input 3 corresponds to IN_EN 0x0949 [3], IN_PULSED_CMOS_EN 0x0949 [7]
Table 16.286. 0x094A Input Clock Enable to DSPLL
Reg Address
Bit Field
Type
Setting Name
Description
0x094A
3:0
R/W
INX_TO_PFD_EN Value calculated in CBPro
Table 16.287. 0x094E-0x094F Input Clock Buffer Hysteresis
Reg Address
Bit Field
Type
Setting Name
Description
0x094E
7:0
R/W
REFCLK_HYS_SEL Value calculated in CBPro
0x094F
3:0
R/W
REFCLK_HYS_SEL
0x094F
7:4
R/W
IN_CMOS_USE1P8
Si5397/96 Reference Manual
Si5397C/D Register Map
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