DS25MB100-EVK
Signal Conditioning Mux-Buffer
Demo Board User Guide
DS25MB100 EVK
P.1
Rev 2.0
4/23/08
Introduction
The DS25MB100 is a signal conditioning 2:1 multiplexer and 1:2 buffer designed to support port
redundancy. Advanced signal conditioning features utilizing input equalization and output driver
de-emphasis enable data communication over FR4 backplane or cable at 0.25 - 2.5Gb/s.
The DS25MB100 demo board is designed to assist customers to evaluate the functionality and
performance. All input and output ports of the DS25MB100 are brought out to SMA connectors for
accessibility to instrumentation.
Evaluation Kit Content
This evaluation kit consists of the following components:
(1) DS25MB100 demo board
(2) Demo Board User Guide (this document)
(3) Demo board schematic
DS25MB100 Demo Board
VCC
GND
SMA
IN-
IN+
OUT-
OUT+
J16
DS25MB100
S8
DEL_1
GND
Open
GND
S1
LB0
Open
Open
DES_1
GND
Open
S5
S4
DEL_0
GND
MUX
GND
Open
GND
LB1
Open
Open
DES_0
GND
Open
S7
EQL
S6
GND
DS25MB100 DEMO
S9
EQS
GND
S3
Open
S2
OUT0+
OUT0-
IN0+
IN0-
OUT1-
OUT1+
IN1-
IN1+
SMA
DS25MB100 EVK
P.2
Rev 2.0
4/23/08
Connection Diagram
VCC=3.3V
DS25MB100-EVK
DC Block
Pattern
Generator
Oscilloscope or
Jitter Measurement
Instrument
DS25MB100
50
D+
IN+
D-
IN-
EQ
R
M
U
X
OUT+
D
OUT-
50
TRIG
1000mVpp
differential
GND
TRIG
Figure 1. Typical connection for evaluation of the DS25MB100
Power
VCC
GND
JP17
J16.3/4
JP20
J16.1/2
3.3V ± 5%
0V
EQ controls
EQL
EQS
S6
J21
S3
J3
EQL enables or disables Equalizer at the line-side (IN±).
EQS enables or disables Equalizers at the switch-side (IN0± and IN1±).
When EQL or EQS is open, it is logic 1 (equalizer bypassed).
When EQL or EQS is strapped to GND, it is logic 0.
De-emphasis controls
DEL_0
DEL_1
DES_0
DES_1
S4
J4
S1
J1
Set de-emphasis level for all outputs at the line side (OUT±).
When DEL_1 or DEL_0 is opened, it is logic 1.
When DEL_1 or DEL_0 is strapped to GND, it is logic 0.
S7
J22
S9
J25
Set de-emphasis level for all outputs at the switch side (OUT0±, and
OUT1±).
When DES_1 or DES_0 is opened, it is logic 1.
When DES_1 or DES_0 is strapped to GND, it is logic 0.
Mux controls
MUX
S2
J2
Set the multiplexer position to select IN0± or IN1±.
When MUX is opened, it is logic 1 (selects IN0±).
When MUX is strapped to GND, it is logic 0 (IN1±).
Loopback controls
LB1
LB0
S8
J24
S5
J5
Enable or disable loopback.
When LB0 or LB1 is opened, it is logic 1 (No loopback).
When LB0 or LB1 is strapped to GND, it is logic 0 (normal mode).
RSV control
RSV
JP8.2
Reserved for factory testing purposes.
JP8.2 is permanently tied to GND.
Switch S and jumper J are connected in parallel for each logic control pin. When switch is being
used, jumper should be kept open. When jumper is used, the corresponding switch should be
kept at OFF position.
DS25MB100 EVK
P.3
Rev 2.0
4/23/08
Logic control for data paths
Following tables list the logic states of the control pins used to configure the data paths of the
DS25MB100. More detailed information about pin functions and pin descriptions can be found in
the DS25MB100 datasheet.
Table 1. Logic table for multiplex controls
MUX
Mux Function
0
1 (default)
MUX select switch input, IN1±.
MUX select switch input, IN0±.
Table 2. Logic table for loopback controls
LB0
Loopback Function
0
1 (default)
Enable loopback from IN0± to OUT0±.
Normal mode. Loopback disabled.
LB1
Loopback Function
0
1 (default)
Enable loopback from IN1± to OUT1±.
Normal mode. Loopback disabled.
Table 3. Line-side de-emphasis controls
DEL_[1:0]
De-emphasis
level in mVpp
(VODB)
De-emphasis
level in mVpp
(VODPE)
De-emphasis in dB
(VODPE/VODB)
Typical FR4 board trace
00
01
10
1 1 (Default)
1300
1300
1300
1300
1300
920
650
461
0
-3
-6
-9
10 inches
20 inches
30 inches
40 inches
Table 4. Switch-side de-emphasis controls
DES_[1:0]
De-emphasis
level in mVpp
(VODB)
De-emphasis
level in mVpp
(VODPE)
De-emphasis in dB
(VODPE/VODB)
Typical FR4 board trace
00
01
10
1 1 (Default)
1300
1300
1300
1300
1300
920
650
461
0
-3
-6
-9
10 inches
20 inches
30 inches
40 inches
Table 5. EQ controls for line or switch side
EQL or EQS
0
1 (default)
DS25MB100 EVK
Equalizer Function
Enable equalization
Equalization disabled.
P.4
Rev 2.0
4/23/08
Typical output waveforms
The followings are typical eye diagrams of the DS25MB100 using demo board connected as
shown in Figure 1.
Figure 2a-b. Eye diagrams at 2.5 and 1.25 Gb/s, PRBS7 pattern, Pre-emphasis=0dB
Figure 3a-b. Eye diagrams at 2.5 and 1.25 Gb/s, PRBS7 pattern, De-emphasis=9dB
Reference Material
DS25MB100 datasheet
National web site http://www.national.com/appinfo/lvds/
DS25MB100 EVK
P.5
Rev 2.0
4/23/08
DS25MB100-EVK board schematic
DS25MB100 EVK
P.6
Rev 2.0
4/23/08
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