The MAX3814 TMDS™ EQ/driver IC compensates for
FR-4 and cable losses up to the DVI™/HDMI®transmit
connector and provides a fully compliant DVI/HDMI
TMDS output. The device can also be used in DVI/HDMI
cable applications to extend reach and improve jitter
margin of cable channels at the receive-side connector.
The on-chip TMDS drivers operate at a standard current level for implementing a typical DVI/HDMI nonback-terminated transmitter, as well as a 50% higher
current mode for using a 200Ω back termination resistor (nonmatching) to achieve a 10dB return loss.
Typical DVI/HDMI output drivers contribute to reflection
problems between the connector and a typical highimpedance (open) DVI/HDMI Tx output. The selectable
output current (LEVEL pin) gives the option of partial
back termination (e.g., differentially connected 200Ω) to
mitigate the reflection problem effectively while keeping
common-mode offset to a minimum.
The 4-channel implementation treats all channels identically. To allow board layout flexibility for DVI and HDMI
connectors, which have different channel order, the
clock and data channels can be arbitrarily assigned.
The MAX3814 operates from a 3.3V power supply,
standard for DVI/HDMI applications, and is packaged
in a 5mm x 5mm x 0.1mm, 32-pin TQFP package.
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
TMDS is a trademark of Silicon Image, Inc.
DVI is a trademark of Digital Display Working Group.
HDMI is a registered trademark and registered service mark of HDMI Licensing, LCC.
(Typical values measured at VCC= 3.3V, TA= +25°C; external terminations = 50Ω ±1%; min/max values valid over VCC= 3.3V
±0.3V, T
A
= 0°C to +70°C; with external terminations = 50Ω ±1% to voltage = 3.3V ±0.7V. Tested at 1.65Gbps. AC parameters guar-
anteed by design and characterization.)
POWER SUPPLY
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Termination-Supply Voltage Range.......................-0.5V to +4.0V
Signal Voltage Range on Any One Signal Wire ....-0.5V to +4.0V
CML Common-Mode Voltage Range on
Any I/O Pair (sustained) .....................................-0.5V to +5.5V
CML Common-Mode Voltage Range on Any I/O Pair
(sustained, within V
CC
and GND) ...-3.3V to +3.3V, Differential
CML Output Loading (termination)............................0Ω to Open
Operating Ambient Temperature Range ................0°C to +70°C
Storage Ambient Temperature Range...............-40°C to +150°C
ESD Human Body Model, Any Pin .....................................2000V
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
OPERATING CONDITIONS
TMDS EQUALIZER PERFORMANCE
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Supply Voltage V
Operating Ambient Temperature 0 25 70 °C
Data Rate 0.25 1.65 Gbps
Maximum Channel Loss
Source Output Rise/Fall Time
Differentia l Input-Voltage Swing
Maximum Supply Noise
Tolerance
CC
3.0 3.3 3.6 V
At 825MHz, FR-4 microstrip compensate
on curve
20% to 80%, mea sured at source
transmitter (input to channel)
Measured at source transm itter (input to
channel)
DC-5000kHz, all specifications maintained 50 mV
15 dB
240 ps
700 1050 1400 mV
P-P
P-P
PARAMETER CONDITIONS MIN TYP MAX UNITS
DC PARAMETERS
Supply Current 110 140 mA
PARAMETER CONDITIONS MIN TYP MAX UNITS
Residua l Output Jitter (15 x
+ DJ) from 0.25Gbps to
RJ
RMS
1.65Gbps
Subtract source j itter for DJ, 0 to 15dB FR4 loss at
825MHz (Note 1)
The MAX3814 TMDS equalizer/driver accepts differential
CML input data rates from 250Mbps to 1.65Gbps. It consists of four differential CML input buffers, four independent fixed equalizers, four limiting amplifiers, and four
differential CML output buffers (Figure 1). The MAX3814
functions both as an equalizer and as a driver.
As an equalizer the MAX3814 automatically adjusts for
attenuation levels up to 16dB at 825MHz from either
dielectric board losses or skin-effect losses in copper
cable.
As a driver the MAX3814 provides CML outputs. The
CML output is normally open (i.e., no back termination)
and is DC-coupled by transmission line to a termination
at the far end per DVI/HDMI standards. The MAX3814
provides nominally 10mA output-switching currents.
However, with the MAX3814, there is a selectable higher
current drive to accommodate a differential 200Ω back
termination resistor while maintaining the differential
swing of 1000mV
P-P
. This 200Ω back termination resistor
serves to dampen signal reflections returning to the
device from discontinuities in the channel such as DVI or
HDMI connectors, providing a 10dB return loss. See the
The input buffers and the output drivers are currentmode logic (CML). See Figures 2, 3, and 4.
The input buffers consist of a 50Ω load resistor connected
to V
CC
and the input connected to a differential equalizer.
The output drivers are open-collector. The current in
these outputs can be adjusted to 10mA or 15mA with
the control pin LEVEL. For 10mA operation, each opencollector output drives through a transmission line to a
50Ω pullup of the next stage, as shown in Figure 3. For
recommended 15mA operation, the two outputs are
bridged by an external 200Ω back termination resistor
that is subsequently pulled up by a 50Ω resistor of the
next stage, as shown in Figure 4. The ESD structure permits signals to achieve 5.5V absolute maximum ratings,
high common-mode range, and compatibility to HDMI
testing. The back termination resistor should be placed
as close as possible to the MAX3814 in the layout.
The ESD protection for both the input and output circuitry consists of diodes connected to a transient voltage suppressor clamp shown as a Schottky diode in
Figures 2, 3, and 4. For more information about the
function of the suppressor clamp, refer to the
Detailed
Description
section of the MAX3208E data sheet
(www.maxim-ic.com/MAX3208E).
Figure 2. Simplified Input Circuit
Figure 3. Simplified Output Circuit Without Back Termination
Resistor
V
TRANSIENT
SUPRESSOR
CLAMP
IN_+
CC
50Ω
V
T
50Ω50Ω
TRANSIENT
SUPRESSOR
CLAMP
OUT_+
OUT_-
TRANSIENT
SUPRESSOR
CLAMP
IN_-
50Ω
+
-
V
EQUALIZER
CC
ENABLE = HIGH
10mA
LEVEL = LOW
5mA
Output Enable Control
The ENABLE pin is an LVTTL input that allows the user
to shut off the output-collector currents, thereby reducing power consumption of the device. Forcing this pin
high turns the output currents off; forcing this pin low
(normal operation) turns the currents on.
Figure 5 shows a simplified circuit for both the output
and enable controls.
Applications Information
Figure 6a shows a typical TMDS channel from a graphics board of a laptop computer to a remote display.
Maintaining a 100Ω differential impedance for this
channel has its challenges. Besides proper board layout of traces, there are multiple reflection points (A to
H). For example, at interface F in Figure 6a, a circular
arrow shows a reflection at the connector of a remote
display. When these reflections hit another interface,
they reflect again and thus become echoes corrupting
the incident signal. In Figure 6b, the MAX3814 is used
to equalize losses, isolate reflections, and redrive the
transmission line with high fidelity.
Figure 4. Simplified Output Circuit with Back Termination
Resistor
Figure 5. Simplified Input Circuitry for Output Level (LEVEL)
and Enable (
ENABLE) Control
V
T
50Ω
TRANSIENT
SUPRESSOR
CLAMP
ENABLE = HIGH
10mA
LEVEL = LOW
5mA
OUT_+
200Ω
OUT_-
BACK TERMINATION
50Ω
V
CC
44kΩ
LEVEL,
ENABLE
INPUTS
88kΩ
44kΩ
50kΩ
TRANSIENT
SUPRESSOR
CLAMP
MAX3814
Laptop PC TMDS Equalizer and Driver
As shown at location XX in Figure 6b, the MAX3814
equalizes trace losses and redrives the TMDS outputs
at the docking connector. The 200Ω resistor at the output of the MAX3814 absorbs reflections from the docking connector.
Dock or Port Expander
The MAX3814 can also be used on the dock or port
expander as it equalizes loss, isolates the connector,
and redrives TMDS output signals at location YY as
shown in Figure 6b. Similarly, with the previous applica-
tion, the 200Ω resistor at the output of the MAX3814
absorbs reflections in this case from the DVI or the
HDMI connector.
An optional 2dB to 6dB attenuator pad can be used to
absorb reflections between internal interface connections. If used, the attenuator pad must be a matched Pi
or T attenuator network. The resulting flat through loss
can be made by the excellent input sensitivity of the
MAX3814 as shown in the
Typical Application Circuits
.
The MAX3814’s excellent input sensitivity allows the
attenuated signal to be restored.
Figure 6a (top). Schematic Showing the TMDS Signal Channel from the Laptop Graphics Boards to the Remote Display. Possible
Reflection Interfaces are Labeled A to H.
Figure 6b (bottom). Schematic Showing the Same Channel, with possible location of the MAX3814 to Equalize Losses, to Absorb
Reflections, and to Redrive the Transmission Line.
LAPTOP
GRAPHICS
BOARD
ASIC
MXM
CONNECTOR
DOCKING
CONNECTOR
INTERNAL
CONNECTOR
OR FLEX
DOCK
EXTERNAL DVI/HDMI
CABLE
DVI/HDMI
CONNECTOR
DVI/HDMI
CONNECTOR
REMOTE DISPLAY
50Ω
3.3V
ASIC
50Ω
3.3V
A
BCDEFGH
REFLECTION
INTERFACES
GRAPHICS
BOARD
ASIC
LAPTOPDOCK
XX
MAX3814
50Ω
3.3V
50Ω
3.3V
MXM
CONNECTOR
200Ω
DOCKING
CONNECTOR
PAD
INTERNAL
CONNECTOR
OR FLEX
YY
MAX3814
50Ω
3.3V
50Ω
3.3V
200Ω
EXTERNAL DVI/HDMI
CABLE
DVI/HDMI
CONNECTOR
DVI/HDMI
CONNECTOR
ZZ
MAX3814
50Ω
3.3V
50Ω
3.3V
REMOTE DISPLAY
200Ω
50Ω
3.3V
ASIC
50Ω
3.3V
Cable TMDS Equalizer
The MAX3814 is useful in providing equalization for
cables losses at location ZZ, at the input DVI/HDMI
connector of the remote display. It can equalize cable
lengths of 15 meters of 26 AWG wire and 12 meters of
28 AWG wire. Again, the 200Ω resistor placed at the
output of the MAX3814 absorbs reflections from the
imperfect termination of the ASIC or imperfect transmission-line interconnect.
Layout Considerations
The TMDS CML inputs are the most critical paths for
the MAX3814 and great care should be taken to minimize discontinuities on these transmission lines
between the connector and the IC. Here are some suggestions for maximizing the performance of the
MAX3814.
• The data and clock inputs should be wired directly between the cable connector and IC without
stubs.
• The 4-channel implementation treats all channels
identically. Input and output data channel designations are only a guide. Polarity assignments can be
swapped and channel paths can be interchanged.
• An uninterrupted ground plane should be positioned beneath the high-speed I/Os.
• Ground-path vias should be placed close to the
IC and the input/output interfaces to allow a return
current path to the IC and the DVI and HDMI
inputs.
• Maintain a 100Ω differential transmission line
impedance into and out of the MAX3814.
• To minimize possible reflections, choose the
200Ω back termination option. Place this resistor
as close to the MAX3814 as possible.
• Use good high-frequency layout techniques and
multilayer boards with an uninterrupted ground
plane to minimize EMI and crosstalk. Refer to the
schematic and board layers of the MAX3814EVKIT.
For the latest package outline information and land patterns,
go to www.maxim-ic.com/packages
. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package
drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
MAX3814
TQFP
(5mm × 5mm × 1.0mm)
TOP VIEW
29
30
28
27
12
11
13
INB+
V
CCVCC
INC+
INC-
14
N.C.
OUTB+
V
EEVEE
N.C.
OUTC+
OUTC-
1+2
V
EE
4567
23242220 19 18
LEVEL
INA+
OUTD-
V
EE
ENABLE
IND-
INB-
OUTB-
3
21
31
10
INA-
IND+
32
9
V
CC
V
CC
OUTA+
26
15
OUTD+
OUTA-
25
16
V
EE
N.C.
N.C.
8
17
V
EE
Pin Configuration
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
32 TQFPH32+1
21-011090-0149
MAX3814
DVI/HDMI TMDS FR-4 and
Cable Equalizer/Driver
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
14
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
Corrected T
globals; replaced the package outline drawing with the Package Information table
Changed the operating ambient temperature max from 85°C (max) to 70°C (max) in
the Operating Conditions table; added the package code and land pattern no. to the
Package Informat ion table
= 0°C to +85°C to TA = 0°C to +70°C in the Specification Tables
A
DESCRIPTION
PAGES
CHANGED
2, 3, 4, 13
2, 13
Loading...
+ hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.