# Constant Current Led Driver (non dimmable) to work with PWM

I have 18W lamps that came with non dimmable led drivers. Ive found datasheet for the main chip (ws3441), which included schematics:

and internal block scheme of the chip:

I'd like to add dimming controlled with PWM - 1024 levels. I already have PWM part ready - used 6W lamps before successully. They also came with non dimable led drivers but I replaced power adapters to one one 20V with enogh power, which was not sensitive to the shorts in the circuit made by MOSFETs controled by microchip. For 18W lamps I cannot find right power adapter - 70V / >2A. Anyways, I plan to mount those lamps in different rooms so one adapter will not be enough. The best solution would be to make use of those drivers that came with lamps. I've read a bit and searched over internet for solution, found few interesting topics, two of them below:

but I dont know how to get use of that information to resolve my problem. Basically Im taking following solutions into account:

• somehow disable current sensing and make it fixed (led driver will only be used with this one kind of lamp) so PWM can work properly,
• maybe using additional transformer like shown here would be solution?

Here are photos of the driver:

• Can you ask a clear answerable question? – Andy aka Aug 19 '18 at 19:07
• The original circuit is non-isolated from the AC mains. If you connect any additional circuitry to it without knowing exactly what you are doing you could create a serious safety hazard. – John D Aug 19 '18 at 19:10
• Question is, how to achieve dimming with available hardware? modifications are of course obvious but I'm not looking for answer "buy new driver". – Michał Majeranek Aug 19 '18 at 19:29
• how to achieve dimming with available hardware? Hmm, these drivers are made to a (low) price, the components that are there are to make it do what it does, no more, no less. Generally a driver suitable for dimming is more expensive because it has different (and possibly more) components. If it was easily possible to make a dimmable driver from the non-dimmable design then you would be able to buy those already. So the only answer possible is: buy a new driver. – Bimpelrekkie Aug 19 '18 at 19:43
• what about ideas from attached links? – Michał Majeranek Aug 19 '18 at 19:46

• That driver, new, cost maybe $5. I don't think it is "worth" that much. For the one pictured, I would not give you$1 for it. I would not buy a new one at \$5. Why 12V? I know nothing about any panel. This is the first mention of a "panel". aliexpress.com/item/… – Misunderstood Aug 23 '18 at 0:16