Dimmable led voltage

[oldpaddy]

Hello all, when dimming the led's does the usage wattage drop or does it stay consistent? I would assume the usage drops, but what do I know?

Thanks

 

[oreo57]

Hello all, when dimming the led's does the usage wattage drop or does it stay consistent? I would assume the usage drops, but what do I know?

Thanks

Easiest answer is yes/no.. Wattage stays the same BUT time on changes..
PWM dimming is a stepping type dimming ..Say you have a 1000mA driver and a led A 3V V(f).. That would be 3W electrical output.
Using "Normal PWM" dimming if set to 50% means outputting 3W 50% of the time..
There are other methods of dimming that do change the wattage but they are getting less common.

If you mean does it save "gross watts" over time.. Probably, depending on the other "bits" of circuitry.
Think of it as shutting the switch on/off 100 times a second.

 

[oldpaddy]

Thanks!

 

[outssider]

when I plug mine into a kil-o-watt meter the wattage drops when I dim...

 

[oldpaddy]

Awesome. I wasn't sure if voltage was constant in LED's. I didn't think it was, but I wanted to make sure.

Thanks guys!

 

[mcgyvr]

when I plug mine into a kil-o-watt meter the wattage drops when I dim...

because its averaging it over a time period..

 

[oreo57]

Awesome. I wasn't sure if voltage was constant in LED's. I didn't think it was, but I wanted to make sure.

Thanks guys!

"Output" trace using a PWM driver @ 50% dimming:

 

[oldpaddy]

15yrs ago I knew what those readings mean. I know it's a dc wave, but that's about all I remember. Now it's all Greek. It reminds me of the $40k I spent on college. What a waste.

 

[theatrus]

The slow sag after the drop is leakage, as LEDs are non-linear devices.