I was wondering if someone on the forum might have experience in designing and building with the MBI5026GN chips sold in the shop. I have run into an issue where I seem to be burning out individual output channels on a few of my chips. What I mean by this is that the affected output channel appears to suffer from some current leakage that allows the connected LED to dimly illuminate. It's definitely not stuck fully "on", as the LED does not illuminate with full brightness until it is latched to ON.
I am working on a final project for my ECET associate degree program in which I have used the 5026 chips as the basis of a control board for a 8x8 RGB LED matrix. The board uses 12 of the chips, 4 for each color bank. It's been a long semester of ups and downs, but I'm at the point where I've built my matrix which works properly, built the control board (old school wire wrapping is fun!), and have software written to run the board from an Arduino Uno. On the software side, I have to give much credit to some 8x8x8 cube designers whose control program served as the jumping off point for my code.. I'm much more of a hardware person, so having a template to work off of helped.
I'm about to order some more of the chips from the ESM store, but want to try to ensure I don't continue to "blow" the chips out. The chips I have now have been with me through the design and testing process, and some were definitely in circuits that weren't properly designed at earlier phases. Last night, once my project was fully working, I swapped in all known good chips, hoping that maybe I wouldn't lose any more now that I seem to have a stable design, but after an hour or so I lost another output to the leakage problem.
I'm running the board and LEDs at 5V, and using an R-ext of 860Ω, which yields an output current to the LEDs on the red channels of 20.1ma. The blue and green banks are running at slightly lower currents due to the higher LED voltage drops. Given the information on the data sheet, I don't seem to be exceeding any of the specifications currently.
At any rate, thanks for reading my wordy post. I know it's not possible to troubleshoot based on a post like this, but I was hoping that maybe a more experienced user may have encountered this failure condition before and have some advice. If not, it's not a huge deal, but I would prefer to be able to hang this on the wall after my presentation and enjoy years of pretty colors given the amount of time and energy I've put into the design and assembly of the project.
Thanks for reading!