Boost driver for 9V emitters

I am wanting to build a mule with 12x Bridgelux Thrive 2835 1W emitters that are 9V. The mcpcb I’ll be using has the emitters in parallel, so I am looking for something between 2A-3A.

If I can’t find a suitable driver I plan on using some SunLike 6V emitters. I already have a couple Convoy 6V drivers I could use, but I was really hoping to use the Thrive emitters.

It might be difficult to find a driver specified for 9V, some 6V or 12V drivers may work depending on their output voltage range, if not they can be modified by swapping a resistor, I talked about it here regarding the Noctigon boost driver : Reddit - Dive into anything

Now Hank does this modification for lower Vf red LEDs, so you could order one (by email, they’re not listed on the website) and ask specifically for a red led boost driver (2A).

On the Convoy FC40 driver the resistor to modify is the top one in the second picture : What did you mod today? - #10939 by Haukkeli
330K should do, but it’s possible it works without modification because its outputvoltage range is already mostly below 12V with the stock resistor.

Thanks for the links. I guess I should have searched harder.
I also found this thread about Simon’s XHP35 driver. If I’m understanding things correctly, I can swap R16 to a 376K that should get me 9V output. I’m guessing the FC40 driver is similar.

Yes it’s the same.

I think I’ll order one from Simon. Would you recommend one driver over the other?

I’ve soldered some sense resistors before but never anything that small. Do you happen to know what size they are, I’m guessing 0402?

the FC40 one because there’s a chance it’ll work without modification, “not working” in this case would be the low mode higher than it should be.
They’re 0402 yes.

Thanks again, I’ll order the FC40 one. In the picture for the resistor swap the line drawn looks to be going to the second from the top resistor.

I got a XHP35 and a GT-FC40 driver and am trying to improve the current output.

Do you know what Simon changed between the two?
slightly higher V-out?

Actually I have one lying around, let me test how low it goes.

Min Vout of FC40 driver is 6.5V, that should be low enough for a 9V LED.

XHP35 driver has higher Vout range yes, with a higher value top FB resistor. (R16 in the shematic).
The FC40 driver can’t drive a XHP35 1st gen to full current, Vout range is too low.

That would be even better. The emitters I plan to use at 200mA need about 10V so I was kind of hoping I could get away with using a 12V driver.

I calculated the Vout to be 11V with the formula in the datasheet and the given resistor values for the XHP35 driver, sounds wrong

That’s in constant voltage output, with the constant current regulation it goes higher, the three resistors R9 R16 R17 allow the voltage to swing across a certain range depending on the Op-amp output.

Falstad sim

(Op-amp out is DAC there, cursor on the right)

To where with the XHP35 driver?

14,5V I presume since that is the Vf of the XHP35 with 2.5A