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I’m trying to add a large number of RGB LEDs (70, so 210 outputs) in a fairly small space (basically a keyboard, although it’s a bit bigger than most).

I read on this tutorial and elsewhere about shift registers, and to me the STP16C596 seems particularly good because a) it will drive 16 outputs and b) it obviates the need for resistors because it provides a constant current.

However, this part is obsolete it would seem and unavailable. What’s a good alternative that I will still be able to hand-solder?

This question suggests using an ‘SCT2026’, but the original link is dead, and I get no result on Mouser or Digikey for that part.

Notes

Apologies if any of my terminology is not right – I’m new to this!

I would certainly consider alternative approaches to this problem if there are any. From what I can see, a matrix-based or charlieplexing approach would be

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Leo
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2 Answers2

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I use the STP16CP05 for shift-register type environments (as an SOIC chip - not through hole, but easy to hand solder anyway).

For more complex environments requiring PWM I use the I2C controlled TLC59116. I use it as a TSSOP, but I believe it's available as PDIP.

Both are LED drivers and control up to 16 LEDs each.

Majenko
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  • Ah, okay, I wasn’t aware that SOIC could still be hand-soldered. I guess it’s large enough despite no being through-hole right? – Leo Nov 11 '14 at 22:32
  • TBH I find SOIC chunky. As long as your PCB is good enough and you have a good flux pen you can hand solder TSSOP, TQFP, etc. I regularly hand solder 0.4mm pitch TQFPs with a normal soldering iron. – Majenko Nov 11 '14 at 22:34
  • This is how new I am to this – I’d never heard of a flux pen before, I’ve just been using solder. Okay, I’m going to get hold of a few of these things and give them all a try. – Leo Nov 11 '14 at 22:38
  • The flux pen is the single most important accessory for the hand solderer. I use the SMF12P from ElectroLube. – Majenko Nov 11 '14 at 22:40
  • That’s really useful, thanks for the advice. I’m just checking out how to use these – does this type of flux pen require cleaning afterwards? – Leo Nov 11 '14 at 22:52
  • It doesn't *need* cleaning, but I do clean it anyway - I tend to use large amounts and it leaves it a bit sticky. Isopropyl alcohol is best for cleaning I find. – Majenko Nov 11 '14 at 23:01
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Perhaps you should consider something with a little more "oomph", such as the TLC5940. It's a little harder to use than just a shift register, but a lot more flexible.

Ignacio Vazquez-Abrams
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  • Fantastic, I’d not seen this and its siblings mentioned, looks like it might be worth making the step up for the on-board PWM and dimming. – Leo Nov 11 '14 at 22:36