What is the fundamental difference between a DC step down chopper and a Buck converter?

Thread Starter

Devika B S

Joined Mar 8, 2017
144
Both are used convert DC to DC : from a higher voltage to a lower voltage. I find that Buck converters have the same circuit in various sources. However, there are several circuits titles step down chopper. Is step down chopper a generic term for all DC- DC high to low voltage converter and Buck converter a specific type of step down chopper?
 

DickCappels

Joined Aug 21, 2008
10,153
That is a buck converter.

Step-down applies to nearly anything that reduces the magnitude of a voltage and is not specific to switching regulator technologies. Linear regulators step down DC voltage step down transformers lower AC voltage, etc.

Chopper? A broadly used term but post a circuit of "a step-down chopper" and we will see whether our guesses are correct.
 

MrAl

Joined Jun 17, 2014
11,389

This is the schematic as given in Wikipedia for Buck converter

HI,

We need to see what you are calling a "Chopper". For example a helicopter is not a buck circuit :)

Sometimes a chopper is a circuit that converts a DC signal into an AC version that has amplitude that varies with the DC signal. So if you have say 2vdc input you may have plus and minus 2v square wave output. This kind of cicuit is used for various purposes and strictly speaking it is not the same as a buck because for one thing a buck is a power supply circuit while the chopper in this case is a signal processing circuit. The resulting "chopped" signal may be used in various ways, which includes filtering or transmitting.

There is a chance that you might call the part of the buck circuit that converts the DC input to a PWM signal a chopper, but calling the whole buck circuit a chopper is taking it a little too far i think.
 

MrAl

Joined Jun 17, 2014
11,389
View attachment 141927


The above is a screenshot of a 'step down chopper' from electrical4u.com - a website I usually find reliable.
Hello again,

Strictly speaking that is a chopper. It is not being used for anything though, so it can not be a buck circuit just yet. Add an inductor and capacitor and you get a buck. Add nothing and you have a signal processing circuit.

The phrase "step down chopper" is not really appropriate however as there is nothing yet being stepped down. It's just being chopped. If you USE it as a step down, then you need to have at least one more component added really two though. Then it becomes a step down circuit.
 

DickCappels

Joined Aug 21, 2008
10,153
It is common for people, especially new to a particular field to want terms clarified and occasionally make an error when asking a question.
 

MrAl

Joined Jun 17, 2014
11,389
It is common for people, especially new to a particular field to want terms clarified and occasionally make an error when asking a question.
Hi,

I agree. I think it is also good that they ask so they dont wonder forever. Some people i noticed wonder about things for a long time and never ask about it, until maybe years later.
 

MrNikolaT

Joined Feb 2, 2020
2
I know this thread is years old but I had similar questions at one point and since it was never directly answered I thought I would give it a go for any future curious people

Now this answer isn't 100% correct but its 90% correct a problem I think the other users were having a problem with. The essence of your question is whats the difference between the two.

A chopper circuit is a more general term for a class of circuits. It chops a signal up turning the signal on and off quickly. This can be used for a variety of reasons as in to make zero drift amplifiers etc.
A a chopper used to step down DC voltage would be used to decrease the voltage through Pulse Width Modulation PWM take 5 volts and you then turn it on for a second and off for a second you have and average voltage of half (2.5 volts). now instead of 1 HZ switching you increase this to say 1k Hz so that the item being powered doesn't really care.

A buck converter uses an inductor and often a capacitor to decrease voltage by increasing current. Switching the power supply on and off quickly creates changing current through the inductor since inductors don't like changing current (physics of electromagnetism) it acts as a resistor reducing the voltage. It also stores energy as a magnetic field which allows it to become a current source when the voltage is switched off always allowing power to reach your load but at a lower voltage.
Hope I could help.
 

MrAl

Joined Jun 17, 2014
11,389
I know this thread is years old but I had similar questions at one point and since it was never directly answered I thought I would give it a go for any future curious people

Now this answer isn't 100% correct but its 90% correct a problem I think the other users were having a problem with. The essence of your question is whats the difference between the two.

A chopper circuit is a more general term for a class of circuits. It chops a signal up turning the signal on and off quickly. This can be used for a variety of reasons as in to make zero drift amplifiers etc.
A a chopper used to step down DC voltage would be used to decrease the voltage through Pulse Width Modulation PWM take 5 volts and you then turn it on for a second and off for a second you have and average voltage of half (2.5 volts). now instead of 1 HZ switching you increase this to say 1k Hz so that the item being powered doesn't really care.

A buck converter uses an inductor and often a capacitor to decrease voltage by increasing current. Switching the power supply on and off quickly creates changing current through the inductor since inductors don't like changing current (physics of electromagnetism) it acts as a resistor reducing the voltage. It also stores energy as a magnetic field which allows it to become a current source when the voltage is switched off always allowing power to reach your load but at a lower voltage.
Hope I could help.
Sounds good to me regardless of age of the thread (yeah about 3 yrs now).
BTW, Welcome to the forum.
 
Top