What's the difference between a buck converter and a voltage regulator?

[kloong]

Both converts higher DC voltage to lower ones, no?

Thanks for answering. =)

 

[berkeman]

Both converts higher DC voltage to lower ones, no?

Thanks for answering. =)

A Buck Converter is a form of a switching voltage regulator.

There are several forms of switching voltage regulators (Buck, Bost, Forward, Flyback, etc.), which have different properties for different applications. You are correct that the Buck Converter is used to convert a higher DC voltage to a lower DC voltage. A Boost Converter, for example, does the opposite (low-->high voltage).

In addition to the switching voltage regulators, there are Linear Voltage Regulators. Those use voltage drops across transistors to convert a higher voltage to a lower voltage.

You can learn more about these by going to wikipedia.org, and searching on Voltage Regulator.

 

[vk6kro]

One of the reasons you might use a buck converter instead of a linear voltage regulator is increased efficiency.

Suppose you had a load that required 5 volts at 10 amps, or 50 watts.

If the supply was 50 volts, a regulator would supply 5 volts at 10 amps by taking 10 amps from the supply, dropping 45 volts across itself and delivering 5 volts as output.

The input to the regulator would be 500 watts, though, (50 volts * 10 amps) so the efficiency would be 10%. The other 450 watts would go to heating up the regulator.

A switching buck regulator would take a little more than 1 amp from the supply and deliver 5 volts at 10 amps to the load. The input would be a bit more than 50 watts, depending on the efficiency of the regulator. Efficiencies of better than 80% are possible.

They cost more than linear regulators, and they can generate noise, but switching regulators produce excellent gains in efficiency and reductions in weight of power supplies.