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I am looking to use a Mean Well LDH-45A-1050 DC/DC LED driver with a an LED matrix but crucially to use PWM dimming. Already have perfectly working led with this driver, just looking now to figure out how to use the dimming function. Have tried with a couple PWM devices but either a no-go (no effect) or else dimming can only be gotten by wiring the dimmer direct to the dc input which I guess is only going to cause problems even though the result is fair (some flicker). Some of the dimmer units have an actual PWM output (in addition to direct output for led strip etc) but this does not work with the LDH unit. This particular device is PWM and analogue dimable. See link: Link to Mean Well LDH driver unit document Mean Well themselves decline to comment or recommend any particular dimmer that is a known match for such a unit. Anyone here have any suggestions?

Any feedback would be much appreciated. Cheers, Ken

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  • \$\begingroup\$ Show schematic of how you connected everything. What are these "PWM devices" and how did you connect them? \$\endgroup\$ – winny May 14 '17 at 21:30
  • \$\begingroup\$ It looks like there are several ways to control the brightness. The two easiest ways are with a PWM and with a voltage. Do you have a bench power supply that can be used for experiments? Do you have a bench function generator? Or an arduino or other processor you can use to create a logic level PWM signal? Oscilloscope? \$\endgroup\$ – mkeith May 14 '17 at 21:59
  • \$\begingroup\$ Is your LED matrix scanned? \$\endgroup\$ – jonk May 14 '17 at 22:15
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I assume you want to use a PWM controller.

There are 2 criteria the controller must meet.

  1. The signal voltage must be between 2v and 8v.
  2. The frequency of the the PWM single must be between 1Khz and 10Khz.

1 is easy to find.
2, many controller ads do not specify the frequency.

So I am guessing the "couple PWM devices" you tried had a PWM switching frequency below 1Khz or more likely above 10Khz. A quick look on eBay the ones I found that specified the frequency, it was above 10Khz (13Khz & 15Khz).

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  • \$\begingroup\$ Hi Misunderstood. \$\endgroup\$ – Ken the fish May 16 '17 at 7:06
  • \$\begingroup\$ Hi Misunderstood. Thank you for your feedback. Yes correct, the MeanWell LDH driver unit has a wealth of specs to work with. Analogue dimming is not favored so yes, PWM was the way I was looking to go. The PWM dimming devices I have however, states only operating voltage and power handling W. Totally unknown as to the output of the dimmers but I guess this will be a simple matter of checking with my fluke set to Hz and then DC volts to get the info required. I will look to checking this today. \$\endgroup\$ – Ken the fish May 16 '17 at 7:30
  • \$\begingroup\$ power handling W? That sounds like a motor controller. You don't need Amps or Watts. Just a few mA. Many of these PWM controllers are LED drivers as well. You already have the HLG driver, so all you need is a PWM signal. Search for PWM signal generator. \$\endgroup\$ – Misunderstood May 16 '17 at 7:40
  • \$\begingroup\$ Yes, that's all the specs we have; max load watts for input voltage 12v and 24v, etc. The unit has an output for direct hook up to LED Strip (or similar) and a separate PWM out. I now know the PWM output voltage (I have several units like this one). With the dimmer hooked up to a 24V DC bench supply the dedicated PWM out measures min 4.5v to max 12.16v. I was unable to read frequency using the fluke so that's a fail. I guess that represents a sufficient mismatch to prevent a successful marriage with the Mean Well unit. \$\endgroup\$ – Ken the fish May 16 '17 at 13:30

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