Si5345-44-42-D-RM
Rev. 1.0
23
5.2. Types of Inputs
Each of the four different inputs IN0-IN3 can be configured as standard LVDS, LVPECL, HCL, CML, and single-
ended LVCMOS formats, or as a low duty cycle pulsed CMOS format. The standard format inputs have a nominal
50% duty cycle, must be AC-coupled and use the “Standard” Input Buffer selection as these pins are internally dc-
biased to approximately 0.83 V. The pulsed CMOS input format allows pulse-based inputs, such as frame-sync
and other synchronization signals, having a duty cycle much less than 50%. These pulsed CMOS signals are DC-
coupled and use the “Pulsed CMOS” Input Buffer selection. In all cases, the inputs should be terminated near the
device input pins as shown in Figure 7. The resistor divider values given below will work with up to 1 MHz pulsed
inputs.
Figure 7. Input Termination for Standard and Pulsed CMOS Inputs
Pulsed
CMOS
DC
Coupled
Single
Ended
Standard
AC
Coupled
Single
Ended
100
3.3V,
2.5V,
1.8V
LVCMOS
Standard
AC
Coupled
Differential
LVPECL
INx
INx
50
100
Standard
AC
Coupled
Differential
LVDS
INx
INx
3.3V,
2.5V
LVPECL
3.3V,
2.5V
LVDS
or
CML
INx
INx
INx
INx
50
50
50
50
Pulsed
CMOS
Standard
Si5347/46
Si5347/46
Si5347/46
Si5347/46
3.3V,
2.5V,
1.8V
LVCMOS
50
R2
R1
Pulsed
CMOS
Standard
Pulsed
CMOS
Standard
Pulsed
CMOS
Standard
VDD
R1
(
)
R2
(
)
1.8V
324
665
2.5V
511
475
3.3V
634
365