Texas Instruments CDCM1804 User manual


 
2006 High Performance Analog/CDC
User’s Guide
SCAU009C

IMPORTANT NOTICE
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Copyright 2006, Texas Instruments Incorporated

EVALUATION BOARD/KIT IMPORTANT NOTICE
Texas Instruments (TI) provides the enclosed product(s) under the following conditions:.
This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR
EVALUATION PURPOSES ONLY and is not considered by TI to be a finished end−product fit for general
consumer use. Persons handling the product(s) must have electronics training and observe good engineering
practice standards. As such, the goods being provided are not intended to be complete in terms of required
design−, marketing−, and/or manufacturing−related protective considerations, including product safety and
environmental measures typically found in end products that incorporate such semiconductor components or
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electromagnetic compatibility, restricted substances (RoHS), recycling (WEEE), FCC, CE or UL, and therefore
may not meet the technical requirements of these directives or other related directives.
Should this evaluation board/kit not meet the specifications indicated in the User’s Guide, the board/kit may be
returned within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE
EXCLUSIVE WARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES,
EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR
FITNESS FOR ANY PARTICULAR PURPOSE.
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TI assumes no liability for applications assistance, customer product design, software performance, or
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Please read the User’s Guide and, specifically, the Warnings and Restrictions notice in the User’s Guide prior
to handling the product. This notice contains important safety information about temperatures and voltages. For
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FCC WARNING
This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR
EVALUATION PURPOSES ONLY and is not considered by TI to be a finished end−product fit for general
consumer use. It generates, uses, and can radiate radio frequency energy and has not been tested for
compliance with the limits of computing devices pursuant to part 15 of FCC rules, which are designed to provide
reasonable protection against radio frequency interference. Operation of this equipment in other environments
may cause interference with radio communications, in which case the user at his own expense will be required
to take whatever measures may be required to correct this interference.
Mailing Address: Texas Instruments Post Office Box 655303 Dallas, Texas 75265
Copyright 2006, Texas Instruments Incorporated

EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within the input voltage range of 3 V and 6 V.
Exceeding the specified input range may cause unexpected operation and/or irreversible
damage to the EVM. If there are questions concerning the input range, please contact a TI
field representative prior to connecting the input power.
Applying loads outside of the specified output range may result in unintended operation and/or
possible permanent damage to the EVM. Please consult the EVM User’s Guide prior to
connecting any load to the EVM output. If there is uncertainty as to the load specification,
please contact a TI field representative.
During normal operation, some circuit components may have case temperatures greater than
45°C. The EVM is designed to operate properly with certain components above 60°C as long
as the input and output ranges are maintained. These components include but are not limited
to linear regulators, switching transistors, pass transistors, and current sense resistors. These
types of devices can be identified using the EVM schematic located in the EVM User’s Guide.
When placing measurement probes near these devices during operation, please be aware
that these devices may be very warm to the touch.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2006, Texas Instruments Incorporated

How to Use This Manual
iii
Preface

About This Manual
The CDCM1804/CDCP1803 evaluation module (EVM) allows evaluation of
the CDCM1804/CDCP1803 LVPECL clock drivers. The CDCM1804 provides
three LVPECL and one CMOS outputs, while the CDCP1803 provides three
LVPECL outputs only. This user’s guide provides a brief overview of the EVM,
setup and operation instructions, and typical test results that can be expected.
In addition, it provides recommendations on proper termination, decoupling,
and how to use the CDCM1804/CDCP1803 in single-ended applications, such
as LVTTL, LVCMOS, or other differential clock signals such as LVPECL,
LVDS, HSTL, SSTL−2, CML VML or similar 2.5-V or 3.3-V signals and provide
a differential LVPECL output.
Requesting an EVM
Contact your local marketing or sales representative to request a
CDCM1804/CDCP1803 EVM.
How to Use This Manual
This document contains the following chapters:
-Chapter 1—Introduction
-Chapter 2—EVM PCB
-Chapter 3—EVM Configuration
-Chapter 4 Using the EVM
-Chapter 5—Schematics, Parts List, Board Stackup, Board Layouts, and
References

How to Use This Manual
iv
FCC Warning
This equipment is intended for use in a laboratory test environment only. It
generates, uses, and can radiate radio frequency energy and has not been
tested for compliance with the limits of computing devices pursuant to subpart
J of part 15 of FCC rules, which are designed to provide reasonable protection
against radio frequency interference. Operation of this equipment in other
environments may cause interference with radio communications, in which
case the user at his own expense will be required to take whatever measures
may be required to correct this interference.
For More Information
If you need assitance with this device, please email
[email protected]

Contents
v

1 Introduction 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 EVM PCB 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 Use of the EVM 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Design of Differential Traces 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Other Design Tweaks 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4 CDCM1804/CDCP1803 EVM Kit Contents 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 CDCM1804/CDCP1803 EVM Configuration 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1 Default EVM Delivery 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Mode Setting for CDCM1804/CDCP1803 Through EN, S0, S1, and S2 3-2. . . . . . . . . . . .
4 Using the EVM 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1 EVM Power Connections 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 Applying An Input 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3 Typical Test Results 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 Schematic, Parts List, Board Stack Up, Board Layouts, and References 5-1. . . . . . . . . . . . .
5.1 Schematic 5-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2 Parts List 5-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3 Board Stackup and Layouts 5-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4 References 5-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents
vi

1−1 CDCM1804/CDCP1803 EVM Default Setup 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4−1 EVM Power Connections for the CDCM1804/CDCP1803 Evaluation 4-2. . . . . . . . . . . . . . . . .
4−2 Typical Output From the CDCM1804/CDCP1803 EVM 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5−1 Schematic of the EVM Signal Path 5-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5−2 Top Layer 5-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5−3 PWR1 Layer 5-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5−4 GND1 Layer 5-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5−5 Bottom Layer 5-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-1
Introduction

The Texas Instruments (TIt) CDCM1804/CDCP1803 evaluation module
(EVM) is used to evaluate the CDCM1804/CDCP1803 clock driver (24-pin
MLF) and ease the evaluation of the clock drivers without having to modify
existing board design.
The CDCM1804 clock drivers distributes one pair of differential clock input to
three pairs of differential clock outputs (Y0:Y2) and an additional CMOS output
(Y3) with minimum skew for clock distribution. The CDCM1804 is specifically
designed for driving 50-Ωtransmission lines.
The CDCP1803 clock drivers distributes one pair of differential clock inputs to
three pairs of differential clock outputs (Y0:Y2) with minimum skew for clock
distribution. The CDCP1803 is specifically designed for driving 50-Ω
transmission lines.
Both devices are capable of accepting any differential swing as small as 150
mV and as high as a 3.6-V signal swing, which makes it ideal for signal level
translation. Both the CDCM1804 and the CDCP1803 can accept single-ended
signals such as LVTTL or LVCMOS or other differential clock signals such as
LVPECL, LVDS, HSTL, SSTL−2, CML, and VML or similar 2.5-V or 3.3-V
signals and provide a differential LVPECL output.
The CDCM1804/CDCP1803 are both 3.3-V LVPECL clock drivers
(CDCM1804 provides three LVPECL + one CMOS outputs). This evaluation
module (EVM) is designed to quickly evaluate the CDCM1804/CDCP1803
with flexibility in having single-ended or differential signals or as level
translator. In addition, the CDCM1804/CDCP1803 incorporate a VBB
reference voltage pin to support reception of single-ended input signals such
as: LVTTL, LVCMOS, LVPECL, HSTL, SSTL−2, CML, and LVDS (when the IN
input pair are ac-coupled).
This user’s guide gives a brief overview of the EVM, setup and operation
instructions, and typical test results that can be expected. Detailed information
relating to the CDCM1804/CDCP1803 can be found in the devices respective
data sheets, available from www.ti.com/clocks. A picture of the EVM, with
CDCM1804/CDCP1803 device installed, is shown in Figure 1−1.
Chapter 1

1-2
Figure 1−1.CDCM1804/CDCP1803 EVM Default Setup

2-1
EVM PCB
 
This chapter discusses the use of the EVM and the contents of the kit.
Topic Page
2.1 Use of the EVM 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Design of Differential Traces 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Other Design Tweaks 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4 EVM Kit Contents 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 2

2-2
2.1 Use of the EVM
The board can be used to evaluate device parameters, while acting as a guide
for high-speed board layout. The evaluation board can be used as a daughter
board that is plugged into new or existing designs. See the respective device
data sheets for detailed parametric specifications.
2.2 Design of Differential Traces
As the frequency of operation increases, the board designer must ensure that
the highest signal integrity is maintained. This applies to both, the high-speed
differential and single-ended clock and data applications.
To cover a wide range of usage, each trace of a differential signal pair has been
matched to maintain 50-Ωline impedance.
2.3 Other Design Tweaks
In addition, the 50-Ωimpedance mismatches are reduced by designing the
component pad size to be as close as possible to the width of the connecting
transmission lines. Overall, the board layout is designed and optimized to
support high-speed operation. Thus, understanding impedance control and
transmission line effects are crucial when designing high-speed boards. Pads
are provided for ac-coupling capacitors to level shift signal’s common-mode
to drive other differential signaling applications. If ac-coupling is not desired,
then 0-Ωresistors can be installed instead.
2.4 CDCM1804/CDCP1803 EVM Kit Contents
-CDCM1804/CDCP1803 EVM board
-CDCM1804/CDCP1803 EVM kit documentation (this document)

3-1
CDCM1804/CDCP1803 EVM Configuration
  !
LVPECL drivers are generally loaded with 50-Ωresistors to a termination bias
voltage, VT. VT is usually 2 V below the supply voltage of the driver circuit.
When the driver operates from a 3.3-V supply, VT is set to approximately 1.3 V.
The EVM has been designed to support the various I/O signaling and output
termination.
The CDCM1804/CDCP1803 EVM board gives the options for operation, some
of which can be soldered into the EVM or connected through input connectors.
Topic Page
3.1 Default EVM Delivery 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Mode Settings for CDCM1804/CDCP1803 Through EN, S0, S1,
and S2 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 3

3-2
3.1 Default EVM Delivery
The board is normally delivered in a default configuration that requires external
clock inputs at IN pair. The CDCM1804/CDCP1803 is shipped with default op-
eration. Many test set-ups can be used to evaluate the
CDCM1804/CDCP1803 functionality.
3.2 Mode Settings for CDCM1804/CDCP1803 Through EN, S0, S1, and S2
ÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎ
Î
Î
ÎÎ
Î
ÎÎ
ÎÎ
Î
Î
60 k
VDDP
VDDP/2
GND
ÎÎ
ÎÎ
60.4 k
Note: This 60−k pullup is internal to the
CDCM1804 and the CDCP1803
Figure 3−1.Mode Settings for CDCM1804/CDCP1803 Through EN, S0, S1, and S2
3.2.1 Jumper Settings
Control input incorporates a 60-kΩpullup resistor. Thus, it is easy to choose
the input setting by designing a resistor pad between the control input and
GND. To choose a logic zero, the resistor value must be zero. Setting the input
high requires leaving the resistor pad empty (no resistor installed). For setting
the input to VDD/2, the installed resistor needs a value of 60 kΩwith a tolerance
of 10%.
The CDCM1804/CDCP1803 modes can be chosen by jumper settings for pul-
lup, pulldown, or VDD/2 mode. The EVM includes a 60-kΩpulldown on the
VDD pin, in addition to the on-chip 60 kΩinside the device, in order to provide
a VDD/2.

4-1
Using the EVM
"  
This chapter discusses the use of the EVM.
Topic Page
4.1 EVM Power Connections 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 Applying an Input 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3 Typical Test Results 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 4

4-2
4.1 EVM Power Connections
Figure 4−1.Power Connections for the CDCM1804/CDCP1803 EVM
Pulse
Generator
Oscilloscope
CDCM1804/
CDCP1803
EVM
Power
Supply
+
_
3.3 V
Yn
GND VCC
Matched
cables
SMA to SMA
Yn
Output
50
50
Matched
cables
SMA to SMA
IN
IN
4.2 Applying an Input
LVPECL inputs should be applied to SMA connectors IN pair. The two
differential 50-Ωresistors, R11 and R12, are used to terminate the LVPECL
input.
As shown in Figure 4−1, the power supply is used to provide the required 3.3 V
to the EVM. The EVM ground is connected to the oscilloscope ground through
the returns on SMA. With power applied, the common-mode voltage seen by
the CDCM1804/CDCP1803 is approximately equal to the reference voltage
being used inside the device preventing significant common-mode current to
flow.
4.3 Typical Test Results
Figure 4−2 shows a typical test result obtained with the EVM. Figure 4−2
shows the output of the CDCM1804/CDCP1803 being driven directly into a
50-Ωoscilloscope.

4-3
Using the EVM
Figure 4−2.Typical LVPECL Output from the CDCM1804/CDCP1803 EVM

4-4
Figure 4−3.Typical CMOS Output from the CDCM1804 EVM

5-1
Schematic, Parts List, Board Stackup, Board Layouts, and References
#$%  &%  #'(% 
&)%  !
This appendix contains schematics, corresponding parts list, board stackup,
board layout and references for the CDCM1804/CDCP1803 EVM.
Topic Page
5.1 Schematic 5-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2 Parts List 5-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3 Board Stackup and Layouts 5-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3 References 5-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 5

Schematic
5-2
5.1 Schematic
Figure 5−1.Schematic of EVM Signal Path