Dedicated driver for 7x11 LED matrixes? - Page 1
Forum section: electronics / beginners

author: LinuxHata
author_rank: Frequent Contributor
timestamp: May 13, 2023, 09:40:51 pm
content: Hello.There are a lot of 7X11 LED matrixes on the market. I bought couple of them, they have cathodes from 7x side and anodes from the 11x side. The question is, since such matrixes are made, there should be some dedicated circuitry to drive it?I know the mutliplexing options with transistors, I know about generic LED drivers like MAX7219, HT1632, TM1629A and so on. But all these are designed to drive LED matrixes in mutiple of 8 - like 8x8, 16x8, 32x16 and so on. Of course, these drivers can be also used for driving such LED matrixes, but a lot of outputs would be wasted. So maybe there is some dedicated chip for multiple 7x11 matrixes, about which I don't know?

author: temperance
author_rank: Super Contributor
timestamp: May 13, 2023, 09:47:13 pm
content: You can have a look athttps://www.lumissil.com/home

author: Benta
author_rank: Super Contributor
timestamp: May 13, 2023, 09:51:45 pm
content: What exactly do you mean by "matrix"?Are we talking 7-segment, 11 digits here, or real 7 x 11 dot-matrix?

author: LinuxHata
author_rank: Frequent Contributor
timestamp: May 14, 2023, 05:25:27 am
content: yes, 7 by 11 pixels led matrix.Mostly used in elevators in China.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: May 14, 2023, 06:24:30 am
content: Quote from: LinuxHata on May 14, 2023, 05:25:27 amTotally depends on how the device is driven. You need to read the datasheet, or at least post a link to your product.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: May 14, 2023, 06:34:54 am
content: It is matrix of 7x11 LEDs. They arranged in grid, cathodes go to 7 side, anodes go to 11 side.Have you seen 8x8 LED matrix? Exactly the same construction and arrangement, just instead of 8x8 grid, here is 7x11 grid. How can I explain any simpler?Here's quick example with pinout from google:https://lightkeyled.en.made-in-china.com/product/KCwEVfIrLMhs/China-RoHS-Compliant-2-2-Inch-7X11-Square-DOT-Matrix-Display-with-Pitch-5-7mm.html

author: mariush
author_rank: Super Contributor
timestamp: May 14, 2023, 06:53:55 am
content: Yeah, Lumissil has a bunch of drivers that can n anodes , m cathodes and some drivers that do matrixes, like 144 leds in a dot matrix.exIS31FL3746B :https://www.digikey.com/en/products/detail/lumissil-microsystems/IS31FL3746B-QFLS4-TR/1267554318 current sinksSupport 18×n (n=1~4) LED matrix configurationsIS31FL3728 :https://www.digikey.com/en/products/detail/lumissil-microsystems/IS31FL3728-QFLS2-TR/53197555~8 current source outputs for row control8~11 outputs for column scan controlProgrammable 8×8, 7×9, 6×10, 5×11 matrixIS31FL3729 :https://www.digikey.com/en/products/detail/lumissil-microsystems/IS31FL3729-QFLS4-TR/1267552716 current sinksSupport 16×n (n=1~8), 15×9 LED matrix configurationsand so on ...Even if there's no exact one that does 7x11, you could still treat it as two separate 5x11 matrixes or 2 4x18 for example, and just not use the extra anodes.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: May 14, 2023, 06:46:44 pm
content: Yes I know all that, in fact, drivers I've mentioned are far more cheap than these.But the question is in another thing - how to find best matching driver.Best matching means less orphan pins and more leds driven with single chip.Say I want to drive as much of such modules as possible with a single chip. The best combo appears to be to wire chips in 22x14 matrix, which with 24x16 capable chip, such as HT1632C or similar, will leave 'only" unused 76 outputs, which I don't want to waste.So this is why I asked, maybe there is a dedicated solution for that specific arrangement.

author: spostma
author_rank: Regular Contributor
timestamp: May 15, 2023, 04:59:50 pm
content: The low-cost drivers often cannot supply enough current to drive a displaywith many segments when you need to read the display in sunlight.if you have a 5V microcontroller with 11 tri-state spare outputs, then you could make a charlieplexing driverusing 11 low-cost MMDT4413 NPN+PNP driver transistors and 11x 47R resistors on the common anodes or cathodesto get a cheap 100-150mA segment current driven at 1/11 duty cycle using a 1kHz timer interrupt.

author: edavid
author_rank: Super Contributor
timestamp: May 15, 2023, 07:26:29 pm
content: If you look on LCSC and filter on "13 segment by 7 bit", it comes up with 2 parts, AiP1612 and SM1628C. Maybe worth a look?

author: mariush
author_rank: Super Contributor
timestamp: May 15, 2023, 07:37:05 pm
content: For the 11 anode, 7 cathode version you could probably use an ULN2003A (7 darlingtons) on the cathodes.As for anodes, you could have mosfet or transistor arrays or shift registers to enable only particular anodes and cathodes (of course also current limiting resistors on each cathode) ... no led drivers involved

author: LinuxHata
author_rank: Frequent Contributor
timestamp: June 18, 2023, 03:06:38 pm
content: I finally found one - TM1623 and it's clones like AIP1623 and othersHad a chance to look at elevator control board, so quickly "scanned" it for LED driver