SDI Video Transmitter ICs, which one? - Page 1
Forum section: electronics / projects

author: Yansi
author_rank: Super Contributor
timestamp: June 20, 2017, 11:05:05 am
content: Hello!Just studying around SDI digital video - how does that work, etc... Is somebody with SDI experience here? I have tried to find and list some common available ICs as SDI transmitters, just to study them. However I have not found many of them.Can you list me some types of available ones, that are used today? What I already found only are some rather old and primitive Cypress chipsets even in PLCC packages like CY7B9234 serializer + CY7B9235 controller/scrambler...On the other hand I have found chips like the Semtech Aviia GV7600, which is a rather complex overkill in a BGA package,or an Intersil's TW6872 which is lovely simple, however still on the pricey side with low availability and pain in the ass 0.4mm pitched QFN. (those bitchez!)What significant specimens I have missed on the market? Just asking because I have some ideas what I could use one of these for...Thanks for ideas!Y.

author: Yansi
author_rank: Super Contributor
timestamp: June 20, 2017, 11:40:42 am
content: I'm not as familiar with FPGAs as others might be, but implementing the complete SDI with all the associated stuff would require a significantly larger FPGA. That FPGA would require a metric shitton of aux circuitry, two metric shittons of development (PCB + HDL) and certainly not cheap PCB. (Yes, I am afraid of anything larger than CPLD).I think using specialized IC is the way to go, certainly in this case. I very much like the Intersil solution above, the price is okay for a one-off job, but I fucking hate the QFN package. 76 leads in a 9x9mm package with 0.4mm pitch and exposed pad. God why... I am really uncertain I could solder one of those by hand. 0.4mm pitch QFP, fine. But not a QFN with EXPad below.Y.

author: fcb
author_rank: Super Contributor
timestamp: June 20, 2017, 12:12:19 pm
content: Gennum used to be my goto for SDI/HDSDI video transmitters. National (now TI) also.

author: Yansi
author_rank: Super Contributor
timestamp: June 20, 2017, 12:46:22 pm
content: I have briefly browsed TI's pages and found only a mention of LMH0340 (LMH0040, LMH0050, LMH0070) series chips. Neither of those is available at one-off quantity and costs a nonsense. If not bad enough, inputs are LVDS DDR clocked. (could not handle that, easily) :-(Gennum... isn't that Semtech now? They have nice sets of chips for video. However almost all (if not all) are in BGA, very complex overkill devices.The problem is, one can not look into what the current production is. I am not interested in UHD, just SD resolution now (and low cost), while abiding the KISS principles...

author: Scrts
author_rank: Frequent Contributor
timestamp: June 20, 2017, 05:42:49 pm
content: Are you interested in SD-SDI or HD-SDI, 3G-SDI, whatever SDI? We've always used Altera FPGAs for SDI transmitters.

author: dmills
author_rank: Super Contributor
timestamp: June 20, 2017, 07:11:11 pm
content: We do it with xilinx, but that families are much of a muchness.You will find that that for the most part you don't really buy a transmitter or receiver as such you buy a line equaliser for whatever line rate makes sense and stick an FPGA behind it. Lots of LMH0387s in our 3G stuff.In terms of extra circuitry, a VCXO is useful (Jitter can be an issue with SDI transmitters) SI5351 is useful here with a fixed 25MHz clock via the fabric, but it does not really take that much FPGA, we have product doing 3G with Spartan 3, 270Mb SD should be no real issue (It is actually harder with modern parts because the serdes do not clock slow enough, so you end up oversampling and doing the clock recovery in the fabric!).One thing to watch out for is that SDI has pathologically long strings of 1 or 0 under some conditions, it does NOT do 8b10 or the like, so loop filters and coupling caps need to be bigger then you would expect, it is a nice gotcha.The Semtech stuff is nice, but you do pay for it.