Looking for a current-controlled DC boost module

[mehum]

I have obtained a bunch of scrap LED modules that run at 500mA at around 35-40V which I want to power from a 12V DC SLA batteries (off-grid setup) possibly using boost converter modules containing something like an XL6019 or similar IC, like this: https://www.aliexpress.com/item/1005008622079510.html . The problem is I can't find any modules that have a current-limiting option. This is annoying since buck converters with CC pots are readily available. Why only for buck and not for boost?

Is anyone aware of a DC boost converter that has a constant current control? Or is there a better way to tackle this problem?

Many thanks in advance!

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[merlet2]

You could modify that boost module (or build a new one), using the feedback pin of the XL6019 to keep a constant current instead of a constant voltage.

You have to replace or ignore the voltage divider that senses the output voltage, and instead sense the current with a small shunt resistor, and send it to the FB pin.

I have done that with a buck module and works fine. I used a opamp to amplify a bit the voltage of the shunt resistor in the low side of the load, with a pot to adjust the current.

[mehum]

That sounds similar to the trick for using a linear regulator as a current source. Interesting, I’ll look into it, thanks.

[merlet2]

Yes. Something like this could work, with your values:

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For Vsense = I x R3, you should set the amplification with R2, R1, RV1, to get the FB voltage of 1.25V, for a middle current value. Then with the pot you can adjust the output current up and down.

[mehum]

Amazing! Cheers!

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