Future project proposal: the A-family

Commercial Sellers' Spot
3

LED Choices

Quite a few of these lights are available with many LED choices. Enough to be confusing for buyers. I think that selection should be trimmed for production, but I show all options that I like.
Let me mention some of the LEDs and why I propose to use them.

1. Samsung LH351D (stock and dedomed)

  • fairly cheap
    • and mass-shaving doesn’t cost much
  • single chip (good beam shape)
  • non-flipped chip (no tint shift, good throw when flattened)
  • the most efficient non-flipped single chip that we know
    • though Cree XHP35 deserves a mention as optically it works as if it was a single chip. And at high power levels it’s more efficient than LH351D.
    • Luminus SST-40 deserves a mention too - at high currents it’s even more efficient than LH351D
  • nice tints
  • available in wide range of colour temps and CRIs
  • moderately high Vf
    • lower peak output, especially with weak battery
    • high Vf is good for efficiency with linear driver
      • better sustained performance
    • falls out of regulation quickly
      • but thermals make it drop output quickly too
    • in multi-emitter lights, Vf is actually low
  • fairly small footprint for the performance
  • large die make this LED floody, even after shave

2. Osram Q8WP

  • inefficient, but the best thrower LED that we know
  • expensive
  • only available as low-CRI cool white
  • Osram already has a replacement for it, CSLPM1.TG
    • untested so far
    • The only reason why I use Q8WP in the drawings is that the CSLPM1.TG is untested. If any of those lights is to be produced, I expect it to be produced with CSLPM1.TG actually.
    • Has the smaller brother with the same footprint: KW CSLNM1.TG. It would be better for users who need high sustained throw and are willing to sacrifice lumens for it

3. Cree XP-L HI

  • drop-in replacement for dedomed Samsung LH351D
    • more expensive
    • better throw, worse efficiency
  • good selection of tints, though the high-CRI ones are not commonly loved

4. Luminus SST-40

  • Not a drop-in replacement for dedomed Samsung LH351D, requires its own boards
  • dedomed, makes a good LED for high-output throwers
    • strictly better than XP-L HI
  • only CRI70 cool white

5. Nichia E21A

  • requires its own boards
  • used as a quad is more efficient than any other 3V LED in 5x5 mm footprint
    • not great when you use just one though
    • similar quad (or even 9-up) could be constructed from Cree XD16. It would offer higher output, but much lower efficiency
  • great tints
  • up to CRI 9080
  • not cheap
  • very low Vf, needs a regulated driver (not a problem for A-lights)