2024. Need 5x7 LED matrix driver IC, which won't have "Unobtanium" status. - Page 1
Forum section: electronics / beginners

author: LinuxHata
author_rank: Frequent Contributor
timestamp: January 09, 2024, 12:49:00 pm
content: I have a bunch of LTP305G displays, so want to build something useful from these.I do have 2 pcs of MAX6952 and MAX6953, but I'd like to get some cheaper solution (these IC cost around $30 each) in case I'll decide to do more.I searched the google and seem like there is not much alternative?There are some Toshiba chips, TB62713, as well as soviet chips, but none available for sale. I also visited this thread:https://www.eevblog.com/forum/projects/5x7-led-matrix-driver-for-variable-width-fonts/Also none available.I don't want to use separate row/column multiplexing and to deal with these timings by myself. I just need a completed solution, with either SPI/I2C or any kind of interface.Seems there is none available for purchase right now, except these MAX6952/3 ?

author: CaptDon
author_rank: Super Contributor
timestamp: January 09, 2024, 01:27:34 pm
content: Sadly the very 5X7 displays you speak of are going the way of dinosaurs as well as the less popular driver I.C.'s for them. You are stuck with an answer you don't want. At the very least I think you will be stuck with buffer I.C.'s and current limiting resistors or possibly constant current drivers if such are made / available. It is so easy to do the scan / multiplex or even 'one segment, one GPIO pin' on FPGA's. I use Xilinx CPLD's to do tasks similar to yours. Sadly, I can't do VHDL or Verilog, never learned it. But, you can use a Xilinx helping hand called 'Schematic Capture' and simply build your logic as if you were wiring TTL/ CMOS gates. It really can be that simple. With the processing world moving on to all of these ATMEGA building blocks and even the older relics like the 'Basic Stamp' or the faster more powerful BS-2 and everything since, the world of demand for dedicated 5X7 drivers and similar has disappeared like a magic show. Even the old Intersil and similar dedicated 7 segment scanner drivers have gone to landfill heaven. Sadly, very sadly, the U.S. government wants tax money on 'inventory' and businesses are simply writing this old stuff off and sending it to the dumpsters!! I saw one of the best auto parts stores with a deep inventory of older parts simply trash 'everything upstairs' where they kept slow moving items. They didn't even try to market the stuff to a specialty house as they didn't feel the time wasted was worth the money they might receive.

author: Ian.M
author_rank: Super Contributor
timestamp: January 09, 2024, 02:16:24 pm
content: If you only want to drive a few LTP305G displays, MAX7219 clones are readily and fairly cheaply available from LCSC and will drive up to an 8x8 bit addressable matrix (i.e. one per 5x7 display). Their ratings are however pure Chinesium so I would configure them at no more than 50% of their rated max. current.However somewhere around eight characters it will become more cost-effective to go to multiplexing the complete multi-character matrix yourself, managed by your MCU, with discrete high-side P-MOSFETs, and TPIC6C595 (or 596) low side power N-MOS shift registers with a resistor array (or discrete resistors) for each to limit the individual LED currents. I made several proposals in thehttps://www.eevblog.com/forum/projects/5x7-led-matrix-driver-for-variable-width-fonts/topic, most of which are valid for your displays. The decimal point complicate things slightly, but its probably simplest to treat it as a whole column so have six high side drivers rather than five. To save money on a large matrix, you could pair individual digits on a single TPIC6C595 and double the number of high side drivers, using 1:12 multiplexing.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: January 09, 2024, 02:24:52 pm
content: Sorry I forgot to clarify, I need the IC with decoding and built-in font display capabilities. So MAX7219, HT16k33 and others won't work.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 09, 2024, 02:34:16 pm
content: Quote from: LinuxHata on January 09, 2024, 02:24:52 pmWhy can't you do this in software?

author: Ian.M
author_rank: Super Contributor
timestamp: January 09, 2024, 02:47:59 pm
content: Quote from: LinuxHata on January 09, 2024, 02:24:52 pmFixed that for you. Your problem is you want Kobe Filet Mignon at a 'Hamburger steak' price point! If you are buying min.27, Rochester Electronics have MAX6953 in PDIP 40 package at under $10 each:https://www.rocelec.com/part/MAXMAX6953EPL-which if you've got ~100 or so displays to use up, or could offload some to friends, would go a long way to getting down to a 'Chuck steak' pricepoint.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 09, 2024, 02:53:09 pm
content: ISSI make a number of matrix LED drivers, e.g. IS31FL3732AYou're not going to get the font stuff but that's easy enough to do in software

author: LinuxHata
author_rank: Frequent Contributor
timestamp: January 09, 2024, 04:38:30 pm
content: PDIP40 is way too big.It is bigger than 10X LTP305If go to PDIP40, there are some obsolete, but still being sold NSemi chips for that.I want something compact - above mentioned MAXs come in TSSOP package, so that chip can be hidden behind 4X LTP305 so won't take an extra space.

author: tszaboo
author_rank: Super Contributor
timestamp: January 09, 2024, 04:45:45 pm
content: There is a Chinese factory called Titan Micro (TMI), that makes LED and LCD drivers. I'm quite sure you will find one that does this, but you have to dig through their datasheets yourself.http://www.titanmec.com/product/display-drivers/led-panel-display-driver-chip/p/1.htmlLCSC sells them, they are cheap.

author: Ian.M
author_rank: Super Contributor
timestamp: January 09, 2024, 05:03:36 pm
content: Quote from: LinuxHata on January 09, 2024, 04:38:30 pmAgain, you want the fancy stuff cheap. Rochester have the TSSOP36 version at $17 each:https://www.rocelec.com/part/MAXMAX6953EAX-with min qty 15, which is better than the $30 you mentioned from your usual supplier, but the prospect of $260 +P&P +tax, just for the drivers does not fill me with joy.That buys a *LOT* of pizza + energy drinks to fuel late-nite dev sessions to design and write your own slave MCU implementation! Probably not much more trouble than digging through a bunch of Chinese only or badly translated datasheets to find integrated drivers that meet 90% of your requirements (getting font support + D.P. control in a chip that can drive multiple character matrices is a *tall* order)!

author: LinuxHata
author_rank: Frequent Contributor
timestamp: January 09, 2024, 06:41:50 pm
content: I have already contacted titan micro.They were so kind, that they even send me their paper catalog (all in Chinese, btw), which covers complete list of their ICs (and they don't have MOST part of their ICs listed on website, mainly due to copyright issues I believe, since they do PCF8575 and other stuff). But unfortunately, they don't have anything of MAX6952-53 style.As I said before, I do have these MAX6952 and 6953 chips, but since I'm making something that people might want to make for themselves too (not disclosing what it is yet, but you can already guess) and I'm going to make circuit/schematics fully public, I'd like to use some cheap components, that's all.

author: mariush
author_rank: Super Contributor
timestamp: January 09, 2024, 07:04:07 pm
content: mikeselectricstuff already gave you a good recommendation...Issi is now Lumissil, and they have a bunch of drivers that do matrixes :https://www.lumissil.com/products/led-driver/fxledIf you ignore the tiny dot, your digits are more or less 5 sources , 7 sinks ... so for example with a could IS31FL3733B (12 x 16 matrix) -https://www.lumissil.com/assets/pdf/core/IS31FL3733B_DS.pdf- you could have 16 x 24 , so you could control 3 x 3 = 9 digits (you'd use 15 +1 for dots, 21 out of 24 for the 7 segments times 3)Or a single IS31FL3742A - - for 6 x 30 ... so you could have 6 x 28 , 4 digits per driver.