Can 7136 chips be stacked to drive a shortwave UV led

Can 7136 chips be stacked similarly to the 7135s? Made a shortwave UV (265 nm) flashlight using a 6v led rated at 500mA typical and 700mA max. Used a 3.4v boost driver with a single 7136 originally outputting 150 ma. Changed the sensor resistor and getting about 472mA, about all the 7136 can output. Works pretty well and barely gets warm but would like more power, maybe about 600mA. So can 7136s be stacked and any opinions on driving the led at 600mA? Also any suggestions on other drivers that can provide the above output, preferably a 17mm boost but am willing to change the host. The driver seems to handle the 472ma with no hot components but who knows at higher power.

Thanks for signing up, rgh_256!

Had to goggle the 7136… nope.

The 7135 is a current regulator.

The 7136 is a voltage regulator.

Got confoozed at first because there’s a… 7138?.. that regulates 380mA of current vs 350mA of the 7135, but the 7136 is a totally different beastie.

A pair of 7135s will give 700mA vs 600mA, but I’d absolutely NOT push UVLEDs, because they’re way way way less forgiving of overcurrent than regular white (blue) LEDs.

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No. You need something to get the voltage, so a boost driver. If your host can take 20mm tail switch drivers you can use a convoy driver made for XHP emitters. If you need a 17mm driver, you can use a dancelite UVC driver from Kaidomain. THis one is a simple on/off affair. If you’re running a 2S battery config you can run most any buck driver (BD39 or P2500).

Any of these drivers you’ll have to adjust output by modifying the sense resistor to get 500mA of output. If you give me more details I can narrow stuff down more.

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Thanks for responding so quickly. The UV light is for viewing fluorescent minerals and is housed in a Convoy M21A host. The LED I’m using is a PKC-50-F35 265mn chip and it’s kind of pricey. Its absolute maximum ratings are 5.11 W Pd and 700mA Forward Current. The characteristic tables in the data sheets are for IF= 500ma and the percent flux vs mA graph shows 100% relative flux at 500mA. At the 472ma I’m getting now, the table shows 95-96 percent relative flux which is not bad. At 600mW the table shows 117% relative flux which would be over a 20% increase from what I’m getting. That would be nice but don’t want to risk the LED if that’s overdoing it. I’m actually quite happy with it now.
Thanks for your reply.

blwilli: The driver I’m using is the Dancelite from Kaidomain. The R330 was replaced with a R100 so thought it would output 500ma but only measured 470-474. That’s using an automotive multimeter on a 10 amp setting so may not be real accurate. Finally found a graph in a datasheet for the QX7136 that seems to indicate that in practice it outputs a max of about 475ma. If the Dancelite can go above this, would be happy to know but it’s pretty good after the resistor mod. I would greatly appreciate information on modifying the XHP drivers. Have looked at them on the Convoy store but am new to this and didn’t know if they could be modified to bring them down to 500ma. Unfortunately for my pocketbook, I don’t think I’m done with flashlight mods.

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Yeah, “absolute maximum” ratings are like “military speed”, ie, you don’t want to do it if you value the longevity of the device.

500mA is good. A blue/white LED can be pushed way harder, but they’re also cheap enough to not get all worked up about it when output starts dropping. A pricey UVLED that’s already pretty high-strung at its rated current? Nah.

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Thanks, I’ll stay where it’s at. No need to ruin something that’s working. Mabe start on a midwave UV at 308 to 310nM. Any suggestions on an emitter in that range?

Actually, it’s amazing that we even have LEDs in the short UV range. Takes a lot get those short wavelengths.

You are welcome. This is an awesome forum and expect to use it a lot.

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No idea. I just get the complete lights.

Keep in mind that uv LEDs have a very steep deration curve. Running at 500 out of 700 is probably best.

I’ve been using yingfeng emitters and have been pretty happy. If you’re looking for some I’ve got some extra singles and quads.

You can dm me if you are interested.

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Seoul Viosys has a good selection of easy to source high power UV emitters in standard sizes that won’t break the bank