LED driver specs

Thread Starter

Reza85

Joined Jul 18, 2024
4
Hi.What does ×3w stand for in a LED driver specs,for example i have a driver with these specification: LED Driver (12-18)x3W DC36-65v
 

Jon Chandler

Joined Jun 12, 2008
1,596
LED Driver (12-18)x3W DC36-65v

means it will drive a series string of 12 - 18 three watt LEDs at constant current.

The DC output voltage will be between 36 - 65 volts depending on the number of LEDs in the string.

The current will be 12/36 = 333 mA.

This type of LED must be mounted on a heat sink.

SmartSelect_20240718_095729_Edge.jpg
 

dl324

Joined Mar 30, 2015
18,326
I'd interpret the last picture to mean the driver can provide 24-36W.

It seems like an odd way to specify capacity. If a driver can provide 600mA at 42V, output power would be P = I*V = 0.6A*42V=25.2W.

Maybe the manufacturers and/or users of these drivers can't do math.
 

Jon Chandler

Joined Jun 12, 2008
1,596
Heatsink mounting plates to handle different numbers of LEDs are available. These are essentially an aluminum-backed printed circuit board.

My Google powers are lacking today. I have some of these heatsinks in rectangular form that handle a 2×3 array of LED beads, or a long thin strip of 1×16 array. I can't find any examples of these online.

The photos show round plates for 1 and 3 LED beads.

These plates must be mounted to a heatsink. The plate itself will get quite hot if additional heatsinking is not provided.

SmartSelect_20240718_101056_Edge.jpg

SmartSelect_20240718_100848_Edge.jpg
 

Jon Chandler

Joined Jun 12, 2008
1,596
Maybe the manufacturers and/or users of these drivers can't do math.
LED DRIVER

8-12 [number of LED elements]
x3W [rated power of each element]
PF>0.95 [power factor]

Output: 20-42VDC [output voltage range depending on number if LED elements[
Current: 600mA +/- 5 [current through the string]

Three watt KED beads have a forward voltage of 3.2 – 3.4 volts. 600mA through each LED bead is ~ 2W. So a string of 8 LED beads is a power dissipation of ~ 16 watts. A string of 12 LED beads is a power dissipation of 24 watts.

The forward voltage can vary depending on the color of the LED, so these numbers are ballpark reasonable
 

MisterBill2

Joined Jan 23, 2018
27,514
If the supply states "600mA", then it will adjust the voltage within it's capabilities to force a current of 600 mA thru the load. So if the string of LEDs are not made to operate at 600 mA they will have a much shorter lifespan.
A CURRENT REGULATED supply will deliver the specified CURRENT at up to it's rated max voltage.
And usually they are not dimmable. UNLESS they claim to be.
LED Driver (12-18)x3W DC36-65v

means it will drive a series string of 12 - 18 three watt LEDs at constant current.

The DC output voltage will be between 36 - 65 volts depending on the number of LEDs in the string.

The current will be 12/36 = 333 mA.

This type of LED must be mounted on a heat sink.

View attachment 327279
NO, the current from a REGULATED CONSTANT CURRENT supply will be the stated current. And iit that stated current is 600 mA then the LEDs should be rated for 600ma OPERATION.
 
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