HDMI to LVDS Conversion Options

Hello Ajinder Singh,

I am interested in this solution you may have. Could you please specify which ic's are used and if there is some sort of application note that covers such a converter?

Thank you

Murillo,

I am the business development manager for this product area.  We currently do not have anything that will support an HDMI(TM) to LVDS link but I am not sure this is needed.  HDMI(TM) contains audio but LVDS does not.  Do you really need a TMDS(TM) to LVDS translator, DVI --> LVDS?  We could provide a two chip solution for this application if audio is not involved.  The TFP401A or TFP403 DVI recievers hooked up to the SN75LVDS83B FlatLink(TM) transmitter might work depending on the application.  We need to understand what the pixel clock need is for us to determine that we have a potential solution.  Fill free to contact me at r-hubbard2@ti.com.

Regards,

Richard Hubbard

Hi Richard,

We have an application where we need to convert the HDMI to LVDS (video only no audio). Can I use TFP401A or TFP403 and SN75LVDS83B as the  HDMI to LVDS receiver. Is there better solution from TI for single port HDMI.

Thanks n regards

MRK

MRK,

This is our best solution for this application.  We need to understand the pixel clock, bits per color, and refresh rate in order to determine whether this solution has the bandwidth needed.  Once these are known we can have you discuss this with an applicaiton engineer for support.

Regards,

Richard Hubbard

Richard Hubbard,

Wow, glad I ran across these boards, I'm looking to work on a CE class project and decided to do something I wanted to do for myself while I'm at it.  Scouring the net finding no useful information until these posts.  I'm looking for a solution of what you've stated just before... I want to take DVI(from external graphics card) input and convert to LVDS(LCD laptop screen).  Basically I want to take my Lenovo W510 notebook, attach an external desktop graphics card via PCIe ExpressCard expansion board (if TI also has components to make this I would be very much interested also but I plan on just buying a ViDoc), then using the output from that graphics card hook it back up to the notebook's LCD screen and not utilizing the onboard graphics card.

Does this make sense?  And more importantly does TI have all the components to make such a thing happen assuming I know the specifications of my LCD and such.  I can get some help afterwards if I am pointed in the right direction as far as components.  Number of components is not an issue, being bulky isn't a problem, as it is going to be a bulky prototype.

Thanks in advance,

John

Richard,

I am a project trainee and i need to design a HDMI to composite convereter.I went through your post and found out that TI has a solution for

DVI to LVDS conversion.Well the HDMI to DVI conversion is possible via a cable but I don't know whether a LVDS signal will be compatible with

a LCD or not.If not , then please suggest me a LVDS to composite conversion circuit. Moreover do give the circuit and the components required for

a DVI to LVDS conversion.

with regards

Saptarshi dutta chowdhury

Saptarshi,

I need to understand the application in order to understand your need.  Are you trying to drive a panel or a monitor? 

• If you are trying to drive a monitor, usually they do not accept LVDS input signals.  Depending upon the type of Monitor many will accept HDMI, DVI, and/or VGA directly. 
• If you are developing a system that is driving a panel, these usually have a LVDS input.  Some may have parallel, DSI, or eDP inputs.   For this we need to understand the following:
  • Panel Resolution
  • Pixel Clock
  • # of bits per pixel or bits per color.
  • Single Link input or dual link input.

The components needed depend upon the answers above.

Please provide your email address so that I can put in contact with our application team. 

Regards,

Richard Hubbard

Richard

I  actually want to design a HDMI to component converter.I got a suggested solution for this.Do tell me whether this will work or not.

HDMI -----------------DVI---------------TFP401---------------  IP00C725 ------------------------THS8135--------------------------NTSC(Component)

            (via cable)                       (DVI Receiver)          (Down scaler from IChips)        (Video DAC)

I went through the datasheets of TFP401 and THS8135 but couldnot get the same for IP00C725.Do tell me if TI has any other alternatives for this IC.

Moreover TFP401 accepts DVI inputs and gives out  24 bits of even and odd RBG pixels( QE[0:23} and QO[0:23])  but  THS8135 accepts 10 bits of

RBG/YCbCr inputs, then how to interface between this two without any loss of data.

In addition to this if i directly want to connect the output of THS8135 to a TV then from where I will get the SYNC signal as there is no

HSYNC and VSYNC coming out from DAC.

Please help me out. I will soon be posting about the specifications that you want to know.

email id:saptarshi.smit@gmail.com

With regards,

Saptarshi

Saptarshi,

I am away for the office until Tuesday of next week.  We save asked our application engineer to respond to this message.  Undrea will either post here or contact you directly via the email provided above.  This may take a couple of days as we research the THS device.  We do not have any information on the IP00C725.  Here are some questions that may help though.

• Is the IP00C725 really needed?  The TFP401 can work in a single link mode and should be able to drive the THS directly.  What is driving the dual link mode aspect?
• Is the THS8134B fast enough for the application?  It is an 8-bpc DAC for VGA but supports 80MHz pixel clock. 
• We will have to think about the syncs.  It may be as simple as going directly to the VGA connector from the TFP device. 

Regards,

Richard Hubbard

Hi,

I have got several NEC LCD panels (1024x768) having 20 pins LVDS connector. It was originally used with C&T 6550  PCI to LVDS convertor add-on card to be mounted on old Intel Pentium compatible Motherboard during those time when on board VGA right on motherboards were not available. Most of them, we have purchased many years back for Embedded PC solutions at astonishing price of 1000 US$/ piece. It was no of use to us until latest motherboard started to come with direct DVI or HDMI port built right on motherboard. Most of current LCD monitor I have seen is coming with 30 pins LVDS connector may be because of 1280 x 768 size resolution.

Can I convert these DVI or HDMI to drive my 20 pins LVDS LCD panels?

Thanks in advance with regards,

--micropar--

Saptarshi,

If using the TFP401 to the THS8135, the two LSBs would be dropped.  The THS8135 generates the sync signals internally with one external sync provided along with the clock (From the TFP401).  The sync levels are carried in the outputs of the DAC.  The THS8135 datasheet and EVM guide have additional details (http://focus.ti.com/lit/ug/sleu109/sleu109.pdf).

Regards,

Undrea

Undrea,

Will TI be able to provide me with the schematic connections along with all the passive components required for TFP401A.

Regards,

Saptarshi

Richard Hubbard

Is there any EVM for TF401A available.I need that desperately and how to interface it with a THS8135 EVM as the latter

takes a analog RGB input which is then internally converted into a digital RGB via TVP7002 then again back to an analog RGB output.

Please help me out if you can.

Regards,

saptarshi

The TFP401A EVM is not available, we do have a TFP403/TFP410 EVM.  These EVM's are basically DVI repeater boards, with no external probe points or access to the data signals out of the TFP403, only DE, HSYNC, VSYNC and ODCK are accessible.

Undrea,

Can you tell me from the EVM of THS8135 that it is configured there to work in video DAC mode or generic mode and

how will the 8 pixels latency affect my picture image.

Regards,

Saptarshi

Saptarshi,

The THS8135EVM should be configured for generic mode for support of RGB with separate HS/VS.

The final display output will be shifted 8 pixels if HSYNC is not delayed to match the DAC latency.  This could be done at the digital source or with a delay circuit on the THS8135 board.

Hello Richard,

I encountered a question about display interface. Could you please give me some suggestion. Thanks!

In our system, there are two dispaly interfaces: one is 24-bit RGB interface, another is 3-lane HDMI interface. But now we need a Dual-link LVDS interface for Panel.

How can we get this Dual-link LVDS interface?

1. change 24-bit RGB to LVDS. But I can't find this transmittter chips. I only found the chip of 24-bit RGB to single-link LVDS (SN75LVDS83B from TI). Is there any chips from RGB to Dual-link LVDS from TI?

2. Change HDMI to RGB, then RGB to LVDS. But it is too bother, and maybe too expensive. I found TFP403(from TI) can change HDMI to dual lane 24-bit RGB. And DS90C387VJD(from National Semiconductor) can change dual lane 24-bit RGB to dual-link LVDS. Do you have any suggestion to this method? Thanks!

Hi Richard,

I sumbit a question about RGB to dual-link LVDS. Could you give me some suggestion or give me e-mail. Thanks!

Best Regards,

Howard

Howard Chen said:

Hello Richard,

I encountered a question about display interface. Could you please give me some suggestion. Thanks!

In our system, there are two dispaly interfaces: one is 24-bit RGB interface, another is 3-lane HDMI interface. But now we need a Dual-link LVDS interface for Panel.

How can we get this Dual-link LVDS interface?

Howard,

DS90C387VJD from National Semiconductor can receive 24-bit RGB (pixel clock up to 170MHz) and serialize them into dual-link LVDS. With 24-bit at 170MHz, you can support panel up to 1920x1080@60Hz. On DS90C387VJD datasheet (table4, page17), it calls this configuration as "Single Pixel In, Dual Pixel Out". DS90C387AVJD also works.

Peter,

What is the resolution needed?  The Howard Quote can work if you have a 24bit RGB that is fast enough.

A solution using the HDMI port would be to use the TFP401A DVI RX in Dual Link Mode driving two LVDS83B FlatLink Transmitter.

Regards,

Richard

Richard Hubbard said:

Peter,

What is the resolution needed?  The Howard Quote can work if you have a 24bit RGB that is fast enough.

A solution using the HDMI port would be to use the TFP401A DVI RX in Dual Link Mode driving two LVDS83B FlatLink Transmitter.

 

Ricard,

I didn't see the panel resolution in Howard's  post. But personally, I have successfully turned on LG 23" 1920x1080@60Hz LCD together with TFP401A (single pixel out at 146MHz) and DS90C387A (single pixel in at 146MHz, dual pixel out around 74MHz).

Rgds,

Peter

Hi Richard,

We are also interest in similar solution which turn a 1080p HDMI to LVDS and drive a 42" LCD panel directly.  Do you have a reference design for it at the moment?

Max

Max,

At this time we do not have a reference design.  In order for us to understand whether we could provide a solution we would need to understand the interface between the HDMI TX and the panel. 

Examples:

·         Is this truly an HDMI TX with a 148.75 pixel clock, 1.48Gbps data rate, 60fps, and 24bpp?

·         What does the LVDS inputs to the panel look like, Dual Link LVDS?

·         Is HDCP turned off from the HDMI TX?

Regards,

Richard Hubbard

Hi Richard, thanks for your prompt reply

1. Yes, it is a true HDMI

2. This is Dual Link LVDS, ideally run on 120hz

3. DHCP is enabled.

Thanks

Max

Hi Max,

I suggest you consider using the TI TFP501 DVI receiver along with the DS90C387A.

You mentioned 120Hz; 1080p120 requires dual-link DVI or HDMI 1.3/1.4, along with quad-channel LVDS.

Thanks,
RE

how about this one http://www.montest.com/montest-tl.html# ?

Jagadish, thanks for posting the link.  $499 is a lot for that box!  TI has a 2-chip solution to bridge HDMI/DVI to LVDS; see this app note:  http://www.ti.com/lit/an/slla325/slla325.pdf

Thanks,
RE

Hello Richard: Looking into the converation two years ago in regards to the HDMI-->LVDS convertion, I ask., Did TI came up with a single ship solution yet or a reference board?

Armando

(I replied to Armando by email)

Just one thing to point out about that application note:

If you need to support a standard 2 channel LVDS system, the DS90C387A is fine. If you need to support a 2 channel Open LVDS Display Interface (OpenLDI), then you will need the DC-balance mode found in the DS90C387.

Mike Wolfe

DPS APPS / SVA

Hi Everyone,

It is possible to build an interface for quad lvds signal to dual lvds (same pixel clock)?

thanks.

Greetings -

Please expand on this request more, it is not clear.  As Mike noted the DS90C387 is a dual pixel LVDS SER, it can take in 24 bit RGB at say 150MHz, and outputs a dual pixel (8D+C) LVDS interface at 75MHz (since it is twice as wide, aka dual).

I an not clear on what you mean as "quad LVDS to dual LVDS (same pixel clock)", if going from 4 to 2, then for equal bandwidth the clock will also have a factor of  2.

John Goldie
Video Interface - DPS / SVA

Hi Rosse,

Does TI have 1-chip solution to bridge HDMI to LVDS? Thanks!

Howard, no, only the 2-chip solution for this function.

Best regards,
RE

Hi, for a project of mine I am trying to build a HDMI to LVDS solution in order to control a screen with the following characteristics:
- 1280x800 resolution
- 89 MHz pixel clock
- 6-bit per color

I bought a SN75LVDS83B and a TFP403 as suggested, however, I am now reading through the datasheets and, even if the LVDS transimitter has an option for 6-bit per color data, the TFP403 does not seem to support it. Is that so? Is there any workaround to make it work?
Thanks!

Giulio,

These two devices deserialize and serialize 27 bits.  You can simply use a subset of these available bits if you're using 6-bit.  Just drop off the LSBs.  The DVI standard always uses 8-bit.  Your graphics source could conceivably generate 18-bit color data with the LSBs held low, and then leave the corresponding TFP403 outputs floating.

Best regards,
RE

Peter,

I have seen that you have successfully turned on an LG 23" using TFP401A and DS90C387A. I am also working on such a solution, driving a flat panel with lvds using dvi input from some graphic gard. Do you have some tips for me before starting schematics? I have read the guidelines from TI and for the mentioned chips, but more tricky information would be helpfull.

Regards,

Juergen

Juergen,

I would suggest the followings:

1) It is highly recommended that you first need to know where all the RGB bits are going from the

     TFP401A input -> TFP401A output-> DS90C387A input -> DS90C387A LVDS output -> LVDS RX input of flat panel. Trace all RGB bits on a paper was what I did.

2) Obtain the spec for the LVDS input flat panel (bare panel) you will be working on. You need to know the LVDS color bit mapping. Base on the LVDS color bit mapping     of the flat   panel, you need to connect TFP401A output pins to DS90C387A input pins accordingly.

3) TFP401A can output two 24bit RGB pixels from 48 output pins (dual pixel output) OR one 24bit RGB pixel from 24 output pins (single pixel output).  My DVI-LVDS board allowed me to configure DS90C387A to accept either "dual pixel" or " single pixel" from TFP401A. However, I had some display issues on the LG 23" 1920x1080 LCD monitor when TFP401A was in "dual pixel output " mode, and DS90C387A in " dual pixel in-dual pixel out" mode. The moment I configured TFP401A in " single pixel output" mode, and DS90C387A to " single-to-dual mode", the LG 23" worked just fine.

4) Since it is DVI interface, you need to "cheat" the graphics source to generate the correct display timing for the flat panel. Meaning, you will need to do some EDID editing. Since the LG 23" was a LCD monitor, I found a EDID reading tool on internet that allowed me to read the EDID off the LG monitor. I then copied this set of EDID to the EEPROM on my DVI-LVDS board. By doing so, the graphics source would generate the correct display timing for the LG 23" flat panel.

Good Luck!

Peter

Peter,

thanks for your detailed answer. At the moment I try to find out the lvds configuration of my panel.

You talked about a programm which can read out EDID from EEPROM. Do you read out with direct connection to that EEPROM like I2C or just by connecting the panel on a PC?

If you have some links/schematics you could share (j.h.duerrwang@arcor.de) with me, I will be grateful for that.

Greetings

Juergen

Hi there,

This is my first post on the TI forums. I've found a lot of very useful information from very bright individuals on these forums so I'm hoping someone can give me some help on a situation similar to Bernie's.

I'm trying to interface HDMI to LVDS. I am aware of a two chip solution to this using the TFP401A with DS90C387A.

However, the TFP401A doesn't seem to be able to decode HDCP. I found that the TFP501 is HDCP compatible so it will be able to decode the input before it is sent to the DS90C387A (is this correct?).

I haven't been able to find any stock of the TFP501. Is there an alternative to achieve the same result?

I am looking for something that can handle dual pixel.

Please correct me if I have used any incorrect terminology. I've only started reading into these topics over the past 2 days and I would like to learn the correct terminology.

Thank you for your help :)

Ibrahim

Hello,

The TFP401A does not have HDCP support.

The TFP501 is sold only to HDCP-members due to legal requirements, there are some test keys to test the HDCP capabilities but again it is only sold to approved members.

we need to understand your application in order to tell if the TFP401+DS90C387a will work (pixel clock, bits per pixel, frames per second, panel requirements, etc)

Regards.

Hi Elias,

Thanks for your reply. Our company is just a start-up so we have not applied to become HDMI adopters as of yet. We looked into the membership prices and we may be able to afford membership in the near future, but not now. It seems like we will have to stick with the non-HDCP option.

Our application requires us to push images to two screens over one HDMI cable. Some manipulation at the receiver end will allocate frames to each screen appropriately.

Ideally, we are looking to support a 60Hz framerate, with 24 bit colour depth, and a clock rate of around 70MHz.

It looks like the TFP401A and TFP501 share the same pinout, so I'm assuming they can be swapped out at a later date without needing modifications to the design.

Cheers,

Ibrahim

Hello Ibrahim,

The TFP401A is not pin to pin compatible with the TFP501, however we have the TFP403 which is pin to pin compatible with the TFP501.

Can you provide a block diagram of your application?

Regards.

Hello

My customer wants to design digital cluster display and he has TFP401A for DVI receiver and DS90C387A for DVI to 2CH LVDS. Is it okay to use HDMI input instead of DVI? I am concerned about it because the block diagram like below at application notes reads only DVI RX.

Thank you for your support in advance.

Hello,

The TFP401A can decode HDMI signals with video-only.

If the TMDS stream has embedded audio the TFP401A will have issues to detect the blanking periods.

Regards.

Hello,

Could you check that TFP403 also decode HDMI signals with video-only?

Thanks.

Regards,

Derick

Correct,

The TFP403 decode HDMI video-only signals.

Regards.

Hello,

I'm having problems that could be related to TFP401A and I hope someone can help. My goal is to mimic the display of an Android phone on a 10" LCD panel.

Here's what I have done:

1. I've implemented a DVI-to-LVDS converter using the TFP401A and SN75LVDS83B chips. When I feed it signals from the HDMI output of my Asus Laptop, everything works perfectly.

2. Next, I tried to source the signals from an Android phone instead, using an MHL-to-HDMI converter. This time I get nothing displayed (black screen with some fuzzy grey noise) on my LCD panel.

After reading the above post, I started thinking maybe the output from the MHL-to-HDMI converter has embedded audio in it which messes up the detection of the blanking periods. If this is the case, what's the easiest way to get rid of the audio component?

As part of my troubleshooting process, I also tried scoping the signals on the CLK_EDID and DATA_EDID pins on the HDMI connector. I noticed there are short pulses of signals (on both pins) which occur every 500ms or so. Does this suggest something I am not aware of? Maybe HDCP (I kinda ruled this out even though MHL is HDCP-compliant because I'm not streaming HD videos, just streaming the Android menu)? 

Hoping to hear your suggestions/advice on this issue. Thanks very much.

Regards,

WT

Hello,

Yes, it could be related to the embedded audio.

Few things to check:

Connect your android phone directly to a PC through HDMI, is the audio being transmitted?

Connect your phone directly to a PC through DVI, using a HDMI-to-DVI converter, does that work?

Regards.