Si5330
Rev. 1.0 9
3. Functional Description
The Si5330 is a low-jitter, low-skew fanout buffer
optimized for high-performance PCB clock distribution
applications. The device produces four differential or
eight single-ended, low-jitter output clocks from a single
input clock. The input can accept either a single-ended
or a differential clock allowing the device to function as a
clock level translator.
3.1. V
DD
and V
DDO
Supplies
The core V
DD
and output V
DDO
supplies have separate
and independent supply pins allowing the core supply to
operate at a different voltage than the I/O voltage levels.
The V
DD
supply powers the core functions of the device,
which operates from 1.8, 2.5, or 3.3 V. Using a lower
supply voltage helps minimize the device’s power
consumption. The V
DDO
supply pins are used to set the
output signal levels and must be set at a voltage level
compatible with the output signal format.
3.2. Loss Of Signal Indicator (LOS)
The input is monitored for a valid clock signal using an
LOS circuit that monitors input clock edges and
declares an LOS condition when signal edges are not
detected over a 1 to 5 μs observation period. The LOS
pin is asserted “low” when activity on the input clock pin
is present. A “high” level on the LOS pin indicates a loss
of signal (LOS). The LOS pin must be pulled to VDD as
shown in Figure 2.
Figure 2. LOS Indicator with External Pull-Up
3.3. Output Enable (OEB)
The output enable (OEB) pin allows disabling or
enabling of the outputs clocks (CLK0-CLK3). The output
enable is logically controlled to ensure that no glitches
or runt pulses are generated at the output as shown in
Figure 3.
Figure 3. OEB Glitchless Operation
All outputs are enabled when the OEB pin is connected
to ground or below the V
IL
voltage for this pin.
Connecting the OEB pin to VDD or above the V
IH
level
will disable the outputs. Both V
IL
and V
IH
are specified
in Table 5. All outputs are forced to a logic “low” when
disabled. The OEB pin is 3.3 V tolerant.
3.4. Input Signals
The Si5330 can accept single-ended and differential
input clocks. See “AN408: Termination Options for Any-
Frequency, Any-Output Clock Generators and Clock
Buffers—Si5338, Si5334, Si5330” for details on
connecting a wide variety of signals to the Si5330
inputs.
3.5. Output Driver Formats
The Si5330 supports single-ended output formats of
CMOS, SSTL, and HSTL and differential formats of
LVDS, LVPECL, and HCSL. It is normally required that
the LVDS driver be dc-coupled to the 100 termination
at the receiver end. If your application requires an ac-
coupled 100 load, contact the applications team for
advice. See AN408 for additional information on the
terminations for these driver types.
3.6. Input and Output Terminations
See AN408 for detailed information.
4. Ordering the Si5330
The Si5330 can be ordered to meet the requirements of
the most commonly-used input and output signal types,
such as CMOS, SSTL, HSTL, LVPECL, LVDS, and
HSCL. See Figure 1, “Si5330 Functional Block
Diagrams,” on page 2 and Table 11, “Order Numbers
and Device Functionality,” on page 14 for specific
ordering information.
Si5330
Control
LOS
IN
V
DDO0
CLK0
V
DDO1
CLK1
V
DDO2
CLK2
V
DDO3
CLK3
V
DD
1k
Valid Clock
No Clock
0
1
IN
CLKn
OEB
Enable
Disable Disable
Enable
