Sofirn ST2 LED replacement

[mcjtom]

@mcjtom

I like the package but not so much the emitters. I’d like to keep the red as it is but get something throwy with a nicer tint in 5000 K instead of the main SFT42R 6500 K.

I also can’t stand the unfiltered UV glow - so I figured maybe some floddy high CRI in 4000-5000 K instead?

I’m trying to figure out what emitters would be easy to use as replacements - size-wise and current-wise.

Would anybody have a suggestion?

I need some adult supervision here. I figured the white SFT42R has the 5050 pad and the driver delivers some 10 A (at some 3.5 V) on max and ~2 A after stepdown.

The SST08UV-H seems to be using 3535 pad and I imagine not more than 1 A on max.

What LEDs could possibly work as a replacement?

[Qubeet]

@mcjtom

What LEDs could possibly work as a replacement?

Do you mean white LED or UV?

[mcjtom]

Both. I was hoping for something with lower CCT and nicer tint but still somewhat throwy (SFT40 5000 or 3000K, or XHP50.3 maybe?) for white and something floody with high CRI (519a ?) for the UV but I’m not sure what could work well (or at all).

[Qubeet]

Sorry for unclear question. I was trying to confirm that you want to replace the UV led with a white one.
Anyway, you’ve provided the answer.

If I read SST20-UV’s datasheet correctly, in ST2 it has Vf 3.55V in low mode and 4.05V in high mode to run 0.25A and 0.85A current respectively.

I think 519A could be a possible replacement only if the driver for UV channel is constant current one AND it supports much lower Vf.

[QReciprocity42 (efficacy ≠ efficiency)]

I’ve tried SFT40 5000K and it turns blue and won’t replace the SFT42R. I doubt the 3000K would fare better; I would wait for the SFT42R 5000K.

Replacing UV with 519A should be ok, the Vf difference between UV and white LED is on the same order as the Vf difference of the same white LED on different levels; I trust that the driver can handle this just fine.

[Qubeet]

@QReciprocity42

I would wait for the SFT42R 5000K

The waiting is over. Simon listed it today.

[mcjtom]

@QReciprocity42

I’ve tried SFT40 5000K and it turns blue and won’t replace the SFT42R. I doubt the 3000K would fare better

Any idea why? Blue as in overdriven?

[QReciprocity42 (efficacy ≠ efficiency)]

Yep, overdriven–you can see the blue shift during the ramp. The 5000K SFT40 has a phosphor that does not tolerate high power density.

[mcjtom]

@Qubeet

4.05V in high mode

Would it mean that if the UV channel is indeed a direct drive on High, I will burn the 519a?

[mcjtom]

@Qubeet

think 519A could be a possible replacement only if the driver for UV channel is constant current one

Doesn’t look regulated:

[Qubeet]

Since battery’s voltage drops below emitter’s Vf quite quickly you can’t judge by this runtime graph alone.

You could run the test in low mode. If low mode is unregulated then high mode is 100% also. If it’s regulated - unfortunately that would give no clue about high mode, I think.
But that’s just my assumptions.

@mcjtom

Would it mean that if the UV channel is indeed a direct drive on High, I will burn the 519a?

I’m sure you will. 2p battery pack can provide high enough current without voltage sag.
In koef3’s test 519a reached 8 amps under just 3.5volts. Applying 4 volts would be an instaburn I guess.

[mcjtom]

@Qubeet

You could run the test in low mode. If low mode is unregulated then high mode is 100% also. If it’s regulated - unfortunately that would give no clue about high mode

Not sure what to make of it. It’s UV on low. Looks constant enough, but that’s some 4 h - maybe not long enough.