Electronics > Projects, Designs, and Technical Stuff
Cheap LED driver and cheap RGB LED quality
<< < (3/3)
3dgeo:
Hm, I don't like that IS31FL3741 has 9 anodes, it's a bit too much on routing and it reduces light significantly. To get same light amount I have to drive each led @~23mA, that's not a big deal, but cheap LEDS may not like that. Also if I use only 8 anodes I would get only 104 leds instead of 105 I need  :( And leaving out 3 cathodes and using all 9 anodes seems a bit wasteful  ???
Big advantage IS31FL3741 is a memory buffer for entire matrix! In my current configuration I have to send new data if I change active fet.
Also there is "open detection" and "short detection" – I'm guessing it's used for key press detection?  :o If so than's a very nice feature!

IS31FL3731 – can't see myself using this chip.
LP5036 – has very nice features, tho way too expensive.

I will nag LCSC about IS31FL3741, if they can get it at descent price I'll role with them, otherwise IS31FL3236A.
3 * IS31FL3236A I would give 35*3 + 1  extra output per chip (I'm using free outputs to reduce resistance on R_EXT and increase LED current if PSU allows it).


--- Quote from: mariush on November 17, 2019, 10:16:59 am ---but it would be a bitch to do the wire layout for a 35x3 display ... lots of traces on just two layers. Going with 4 layers would significantly reduce the PCB difficulty but what you save on led drivers, you put in the circuit board.

--- End quote ---

Tell me about it ;D I have working 2 layer PCB prototypes with 45x7 (3 ICs with 16 outputs), and it is tight..... Tho I managed to squeeze 0.3mm traces, but if my assumptions are correct with new ICs I have room for 0.15mm at best and some traces are 25cm long.
No, my assumptions were wrong, if I use this chip routing will be at the same level or even simpler!

Edit:
I noticed in datasheet that IS31FL3741 has resistors on every input (20/51ohms), but no info on them. If they are required this chip is not suited for me, I don't have place for 39 resistors on the PCB, plus PNP cost will be huge...
Navigation
Message Index
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod