SMPS and resonance? - Page 1
Forum section: electronics / general

author: vlad777
author_rank: Frequent Contributor
timestamp: February 03, 2016, 07:21:09 pm
content: What do I need to know about "resonance" to use a chip like this:OFF-LINE QUASI-RESONANT FLYBACK SWITCHING REGULATOR (G6153)http://radiocom.dn.ua/image/data/pdf/STRG6600.pdfhttp://pdf1.alldatasheet.com/datasheet-pdf/view/396127/IRF/IRIS-G6351S.htmlWhat is suppose to be a resonator here (LC tank?) ?(Here is what wikipedia says:https://en.wikipedia.org/wiki/Resonant_inverter)

author: Neilm
author_rank: Super Contributor
timestamp: February 03, 2016, 08:08:19 pm
content: The resonant part is the winding of the transformer with a capacitor near it. There are two sorts - parallel and series. In commercial supplies you will see that the primary and secondary windings are split so there is reasonably poor coupling between them. This generates the "tank" that is part of the resonant system.There are several papers out there on the subject - have a look at AN-4151 from Fairchild or AN2644 from ST

author: owiecc
author_rank: Frequent Contributor
timestamp: February 03, 2016, 08:14:14 pm
content: What is your question? If you just want to use the chip then open any datasheet or app note and make the circuit described there. If you want to learn about the topology then read a few app notes. They are typically very good at descibing what is the purpose of the circuit and how the resonance is achieved and what are the limits of operation.

author: vlad777
author_rank: Frequent Contributor
timestamp: February 03, 2016, 08:27:04 pm
content: Quote from: owiecc on February 03, 2016, 08:14:14 pmI want to be able to make a flyback SMPS using integrated solutions, but I learn that there are "(QUASI) RESONANT" types.

author: vlad777
author_rank: Frequent Contributor
timestamp: February 03, 2016, 09:12:47 pm
content: So it is always good to search on youtube. I searched for "quasi resonant converter".There are few types: quasi, parallel, serial and LLC (series parallel) .The only point of resonance is to achieve ZVS (zero voltage switching) or ZCS (zero current switching), which improves efficiency and reduces EMI.It seems that quasi designation ,means that chip works in a certain way, rather than that I have to implement it in a special way.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 03, 2016, 10:44:06 pm
content: Quote from: vlad777 on February 03, 2016, 08:27:04 pmWell just because they exist, doesn't mean you have to use them...?UC3842 is an old classic, for conventional flyback purposes.Tim

author: vlad777
author_rank: Frequent Contributor
timestamp: February 03, 2016, 11:22:38 pm
content: Quote from: T3sl4co1l on February 03, 2016, 10:44:06 pmThanks for the info.G6153 is a nice one, because everything is integrated in 5 pin to220.

author: owiecc
author_rank: Frequent Contributor
timestamp: February 04, 2016, 04:46:03 pm
content: Quote from: vlad777 on February 03, 2016, 09:12:47 pmLook at how the whole converter works. Converter waits for the resonanse to appear and switches the transistor in the valley, while the voltage is as low as possible. Not entirely ZVS but the losses are reduced. You need both the specific chip but also the correct L C values.