Switched mode power supply vs led driver.

[mattg4321]

This might be a silly question and after 20 years doing this I probably should know the answer, but can a switched mode power supply and an led driver be the same thing?

Example: I had a job the other day and I got a ‘while you’re here request’. Customer has a couple of 12v deadbolts to lock some fancy bifold doors. Crap idea imo as it seems as though in a power cut they will just unlock?!

Anyway, they stopped working a while back. Asked me to investigate. Good customer of mine and didn’t want to take no for an answer! I located the power supply hidden in an adjacent cupboard. Marked 12v dc - 2 amps - switched mode power supply. Tested the output with multimeter. Nothing. Looked like it had been wet at some point too. Decided it was dead!

Went and looked in the van. Found Led driver marked 12v dc - 2.5 amps. Connected up and it didn’t work although showing 12.7v dc with meter . Obviously there could be another fault with the locks but is there any reason why this wouldn’t have worked?

Is a 12v dc power supply the same whether it’s marked led driver or switched mode power supply?

Does the fact that the replacement part was rated at 2.5amps rather than the 2.0 amps of the original part have any bearing?

Cheers

 

[DPG]

This might be a silly question and after 20 years doing this I probably should know the answer, but can a switched mode power supply and an led driver be the same thing?

Example: I had a job the other day and I got a ‘while you’re here request’. Customer has a couple of 12v deadbolts to lock some fancy bifold doors. Crap idea imo as it seems as though in a power cut they will just unlock?!

Anyway, they stopped working a while back. Asked me to investigate. Good customer of mine and didn’t want to take no for an answer! I located the power supply hidden in an adjacent cupboard. Marked 12v dc - 2 amps - switched mode power supply. Tested the output with multimeter. Nothing. Looked like it had been wet at some point too. Decided it was dead!

Went and looked in the van. Found Led driver marked 12v dc - 2.5 amps. Connected up and it didn’t work although showing 12.7v dc with meter . Obviously there could be another fault with the locks but is there any reason why this wouldn’t have worked?

Is a 12v dc power supply the same whether it’s marked led driver or switched mode power supply?

Does the fact that the replacement part was rated at 2.5amps rather than the 2.0 amps of the original part have any bearing?

Cheers

I would imagine all DC power supplies/drivers for LEDs are switch mode these days. The days of linear power supplies are long gone, except for high end audio equipment and some other specialist applications.

 

[Lucien Nunes]

Switched-mode is a technology, used by regular power supply units and LED drivers alike, that uses a high-frequency transformer instead of a 50Hz one, for economy, efficiency and smallness.

When we speak of a DC power supply unit, be it switched-mode or not, we are normally referring to a unit with constant voltage output. Any LED driver that produces a constant voltage output is thus interchangeable up to a point. The specs and performance might differ, e.g. the PSU for a high quality electronic gadget might have better voltage stability, better current surge capability and lower noise than an LED driver, because LEDs are not very critical of these factors. For this reason I would not recommend using generic LED drivers for performance-critical applications because they might have sacrificed one or more of these performance factors for smallness and lightness. OTOH any good SMPSU will work fine as a constant-voltage LED driver.

Constant-current LED drivers are still switched-mode power supplies, but regulated in CC mode rather than CV. These won't generally be suitable for powering electronic loads that want a constant voltage.