Drivers, Power Supplies and Transformers

What’s the difference between a power supply, a driver and a transformer?

The wires in the walls of your home or office usually carry 120 volts AC. And that’s the power that comes from your wall outlets too. But if you connect LEDs directly to that power they will burn out instantly.

So you need a device that will convert the 120V AC power into something suitable for LED lights.

Right. So what is that device called?

Some people call it a “transformer”, some say “power supply” and some say “driver”.

Why all the different names? Are they all the same?

If you tell us you need a transformer or you need a power supply, or you need a driver, we know what you mean. But if you want to be more accurate, read on.

A “transformer” is an electrical part that converts one AC voltage to another, like from 120 volts AC to 12 volts AC for example. It has two coils of thin wires on a metal core. It can’t convert AC power into DC power. For some kinds of lights like old halogen bulbs, a transformer is all you need.

But for LEDs, most power supplies/drivers include more sophisticated electronics, to do conversion from AC power to DC power and other functions. They have transformers inside them, but they have a lot more parts too. Think of it as the difference between toilet and washroom. Sure, a washroom has a toilet in it, but there’s more to a washroom than just a toilet.

Ok, so what about “power supply” vs “driver”? Are they the same?

Kind of. Some say the term “driver” should refer to a “constant current” type of LED power supply, and “power supply” should refer to “constant voltage” power supplies.

What? Constant current? Constant voltage? This is getting too confusing.

Right. That’s why the term “power supply” and “driver” are becoming interchangeable. Purists may argue that’s wrong, but that’s OK.

Thanks for clearing that up! But wait, I have another question. I saw an LED power supply/driver called a “dimmable transformer”. What’s that?

Good question. That’s kind of a hybrid device. It’s mostly just a transformer, but with a couple of extra components to do a crude AC to (almost) DC conversion. They are quite popular in the market, but there are pros and cons to them. That’s a bigger topic for another article though.

In summary: You can call it an LED power supply or an LED driver.

Don’t call it a transformer – unless you’re talking about the dimmable transformer type of product (which we don’t sell) . TLX products aren’t “transformers”, though they do have them inside.

Hope it helps!