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I recently read a seller's description of an LED module that said it should be driven by a constant voltage source but that a version intended for use with constant current power supplies was available upon request.

This got me wondering what differences in the design of an LED module (or array) would dictate whether it should use a constant current or constant voltage driver, and if I bought an LED module whose documentation did not specify what type of driver to use, what should I look for to determine what type of driver I should use?

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In that unit, the description implies that the necessary series resistance to control current through the LEDs is included "on-board," and that the PCB is "wired" to be connected with others in parallel "daisy-chain" circuits.

With the option of adding more modules in parallel, a constant-current supply would only function properly with a fixed number of modules (i.e. a supply meant for 3 would burn up 2, or fail to properly light 4).
However, a constant voltage supply will properly light any number of parallel units, up to the number which will draw more current than your supply can provide.

The "available" constant-current PSU-driven version most likely has a series connection to "daisy chain" modules, and could be made without the series resistance that's necessary in a constant-voltage driven unit.

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  • \$\begingroup\$ "too" many "quotes" distract from the "real" answer. \$\endgroup\$ – dandavis Apr 20 '17 at 0:24
  • \$\begingroup\$ Unfortunately so, but some manufacturers with a marginal (at best) grasp on the english language tend to use misnomers more often than correct terminaology. ... In the end, this makes it so a properly worded answer (thus no quotes needed) would seem even more confusing to the lay-person. ... Unfortunate, but I haven't found a better solution yet. - - As an aside, the quotes around "real" in your comment were grammatically incorrect, but in this one they are correct...gotta love linguistic nuances. \$\endgroup\$ – Robherc KV5ROB Apr 20 '17 at 0:33

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