User's Guide
SNOU126 – September 2013
LMK00725EVM User’s Guide
1
Introduction
The LMK00725 is a low skew, high performance clock fanout buffer, which distributes up to five 3.3 V
LVPECL outputs. The clocks are derived from one of two selectable inputs, which can accept differential
or single-ended input signals.
This evaluation module (EVM) is designed to demonstrate the functionality and electrical performance of
the LMK00725 device. For optimum performance, the board is equipped with 50-ohm SMA connectors
and 50-ohm controlled impedance traces.
Table 1. Device and Package Configurations
DESIGNATOR
IC
PACKAGE
U1
LMK00725
PW-20 (TSSOP 20 pin)
2
Features
•
Easy to use evaluation board to fan-out up to five LVPECL clocks with low phase noise/jitter
•
Accepts differential or single-ended/LVCMOS input clock
•
Device control pins configurable through jumpers
•
Board power at 3.3-V for VCC
3
Setup
This section describes the jumpers and connectors on the EVM as well and how to properly connect, set
up and use the LMK00725EVM.
With this EVM, one could distribute one of two input clocks to up to 5 LVPECL outputs. Therefore, a
minimum of one clock source is needed and appropriate test equipment to observe or measure the
outputs.
3.1
Input/ Output Connector Description
Connectors
:
•
CLK0
and
nCLK0
SMA connectors are used to interface an external AC-coupled clock input to the first
of the two differential input pairs (CLK0, nCLK0) of the device.
•
CLK1
and
nCLK1
SMA connectors are used to interface an external AC-coupled clock input to the
second of the two differential input pairs (CLK1, nCLK1) of the device..
•
Q1
,
nQ1
and
Q3
,
nQ3
SMA connectors are used to distribute two of the five differential clock outputs.
The other three differential clock outputs are not connected to the traces, so their SMA connectors are
not populated by default.
•
PWR
is a 3-pin header used to 3.3-V supply power to the board/device. VCC and GND pins are
labeled on the top side of the board. The center pin is not connected (N/C).
4
LMK00725EVM User’s Guide
SNOU126 – September 2013
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