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

enter image description here and internal block scheme of the chip: enter image description here

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? enter image description here

Here are photos of the driver:

enter image description here enter image description here enter image description here

  • 2
    \$\begingroup\$ Can you ask a clear answerable question? \$\endgroup\$
    – Andy aka
    Commented Aug 19, 2018 at 19:07
  • 1
    \$\begingroup\$ 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. \$\endgroup\$
    – John D
    Commented Aug 19, 2018 at 19:10
  • \$\begingroup\$ Question is, how to achieve dimming with available hardware? modifications are of course obvious but I'm not looking for answer "buy new driver". \$\endgroup\$ Commented Aug 19, 2018 at 19:29
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    \$\begingroup\$ 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. \$\endgroup\$ Commented Aug 19, 2018 at 19:43
  • \$\begingroup\$ what about ideas from attached links? \$\endgroup\$ Commented Aug 19, 2018 at 19:46

1 Answer 1


You cannot add a dimmer to that fixed output LED driver you are using.

You need to buy another LED driver with a dimmer input.

I would recommend an HLG-40H-xxB where xx = the maximum forward voltage. If the LEDs forward voltage is greater than 54V then a HLG-60H-C will do the job.

An HLG type B can be dimmed with a resistance, 0-10vdc, or PWM.

  • \$\begingroup\$ this driver is worth 10 times the LED panel... I've decided to take few panels apart and change it to 12V, so they can be powered and controlled by existing instalation. \$\endgroup\$ Commented Aug 22, 2018 at 19:25
  • \$\begingroup\$ 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/… \$\endgroup\$ Commented Aug 23, 2018 at 0:16
  • \$\begingroup\$ HLG-40 is for 40W and cant suply constant current panel (30x leds in one line) properly. \$\endgroup\$
    – eri
    Commented Aug 21, 2022 at 15:56
  • \$\begingroup\$ @eri Do you know anyone that would want to drive 30 LEDs in series? That's a forward voltage of about 90 volts. It's not about the wattage. A 40 Watt driver can easily drive a long series string of LEDs. You must consider both forward voltage and current desired. If you did, an HLG-60H-C350 would do the job well. It has an output of 100-200 VDC and up to 350 mA. I generally drive LED strips with a 40 V forward voltage. \$\endgroup\$ Commented Aug 22, 2022 at 16:42
  • \$\begingroup\$ 40 Watt driver at cunstant current mode makes 700mA but one module at 60-90V. One module needs 300mA and will burn at 700mA) It ok for 2 lines, but 2 lines is too much. I have 10W 150 mA (in LED) lamp on my table and i cant dim it to 5W. I did not found constant current suply with PWM,SPI,DMX, etc. I have 18W 300mA near bed - i turn lamp to ceiling ) \$\endgroup\$
    – eri
    Commented Aug 22, 2022 at 18:13

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