Just watched the 34063 tutorial - Page 1
Forum section: electronics / general

author: keenox
author_rank: Contributor
timestamp: December 25, 2014, 10:39:30 pm
content: Hello guys!This is my first post on this forum, so be gentle. I just watched Dave's video on 34063 () and was wondering what the role of the inductor is? Someone told me it's for smoothing the output, but I'd really appreciate a more in-depth explanation.Thank you and happy holidays!

author: Stonent
author_rank: Super Contributor
timestamp: December 25, 2014, 11:41:33 pm
content: Afrotechmods to the rescue!Part 1:Part 2:Part 3:

author: Whales
author_rank: Super Contributor
timestamp: December 25, 2014, 11:47:13 pm
content: The inductor is vital to the voltage changing process. It stores energy in the form of a magnetic field, which acts as a middle man between the power going into the buck/boost/invert and the power coming out.Step-up exampleAttached is a shamelessy stolen screenshot of an example step-up circuit from a 34063 datasheet. It's useful for the following explanation as it shows some of the circuitry inside the 34063 too, namely the main driving transistor pair.Order of events for this circuit:(1) Power is let through the inductor at the top using the internal transistorsIn an inductor current flow and the magnetic field around them are directly related. More current flow, more magnetic field, and visa versa.Inductors resist changes in current flowing through them -- you can't instantly change it, it has to gradually change. If you try to push power through an inductor suddenly (like we are doing) at first very little will flow, but it slowly ramps up. If you shut power off, it will try and keep current flowing.We tend to run 34063's in the tens of kHz range so we keep power flowing through the inductor for something like tens of micro-seconds, until it has formed a reasonable magnetic field in the inductor for us to play with.(2) Power is shut off to the inductor.What? No more current flow? The magnetic field chucks a hissy fit and ramps up the voltage on the inductor totryat all costs to keep that current flowing.(3) Our final higher voltage is madeOnce the voltage across the inductor is larger than our (assumedly already existing) output voltage, the diode on the right lets it through and out. This gives a small 'packet' of energy to the output, and the 34063 regulates how often these packets of energy are sent to ensure the output voltage remains at what we want it.Tell me if this is confusing or if it needs work

author: atferrari
author_rank: Frequent Contributor
timestamp: December 26, 2014, 02:10:25 pm
content: Hi Stonent and WhalesIt is evident I am not grasping this in full, but every time I read something like:QuoteI am at lost with what polarity the voltage has (nobody seems to care mentioning it explictly), at both ends of the inductorpriorandafterthe power is switched off.This has been a years long stumbling block.Could you please:Give some values for me to understand? (I have the surely wrong feeling that current goes backwardAny simple experiment to verify all this? Yes I sound stupid asking this...Jointly with electric motors, this is one of my stumbling blocks since I started.Gracias.

author: Andy Watson
author_rank: Super Contributor
timestamp: December 26, 2014, 02:55:49 pm
content: Quote from: atferrari on December 26, 2014, 02:10:25 pmThis bit:Quote from: atferrari on December 26, 2014, 02:10:25 pmThe current will continue to flow in the same direction. Consider what voltage that would generate at the terminals of the coil. It's actually Lenz's law, but you have to view it from the perspective of the coil.