3.1.3 External Input Clock on CLKIN_x/CLKIN_x#
When supplying differential input clocks into the CLKIN_x/CLKIN_x# inputs, AC or DC coupling can be used. The figures below show
the AC and DC coupled differential input clock connection to the Si5332 clock inputs. (There are some restrictions to observe when
using DC coupled input clocks as described further below.) The input clock Format Termination shown in below figures is dependent on
the driver’s termination requirements. The Si5332 clock inputs are high impedance inputs and the clock driven into the Si5332 must
meet the Si5332 Data Sheet's specified electrical requirements. When using differential input clocks, the respective Si5332 input must
be configured as a differential input using CBPro.
0.1 µF
0.1 µF
Controlled
Impedance
VDD Core
CLKIN_x#
Figure 3.3. AC-Coupled Differential Input Clock (LVDS, LVPECL, HCSL, CML, etc.)
Controlled
Impedance
VDD Core
CLKIN_x#
Figure 3.4. DC-Coupled Differential Input Clock
To determine if a specific DC-coupled differential input clock arrangement is supported, refer to the table below.
Table 3.1. Si5332 Input Clock Coupling Restrictions (AC or DC)
Format
VDD_Core
3.3 V
2.5 V
1.8 V
LVDS 3.3 V/2.5 V
AC or DC
AC only
AC only
LVDS 1.8 V
AC or DC
AC only
AC only
LVPECL 3.3 V/2.5 V
AC or DC
AC only
AC only
HCSL
AC or DC
AC or DC
AC only
CML
AC only
AC only
AC only
LVCMOS
AC only
AC only
AC only
Note:
1. For DC-coupled, input clock peak voltage must not exceed VDD_Core and minimum voltage must not be below GND.
2. For AC-coupled, peak swing must not exceed VDD_Core.
Si5332-AM1/2/3 Automotive Grade Device Reference Manual
Input Clocks
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