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I'm using a visualization software in which I created an animated schematic for a part of the free charge controller: http://everycircuit.com/circuit/4838391810097152

The entire schematic is here: http://1drv.ms/1AiMICL (or here)

Hopefully I have this set up right. I am questioning the purpose of C6 and C9. Why are they there? There doesn't seem to be current flowing between the terminals of C6 or C9. What is the main purpose of the induction coil?

I've worked on this now for a spot and I added the MOSFETs I am curious because in Every Circuit simulation there seems to be current flowing through M3 even though M3's gate is not powered at all in my simulation.

I thought that http://everycircuit.com/circuit/6539292895608832 is a good buck converter. It seems that a synchronous buck adds the use of another MOSFET which is used in an opposing configuration where one is on the other is always off and vice versa. That I understand. The power I see flowing in every circuit is just a small trickle at 16.7 mA however its making it through with nothing connected to M3's gate. I'm not sure how that's happening yet.

It seems to be the use of the ground that is causing the flow of current through MOSFET M3 even though the gate is off. Why is this happening?

Another question I have about this design is the MOSFET: http://www.jameco.com/Jameco/Products/ProdDS/669943IR.pdf

Every Circuit software wants to know how many nm's or mm's is the mosfet. I don't know what Every Circuit is talking about yet.

Thank you

Eae
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1 Answers1

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The circuit in the schematic is a power section of a Buck converter. Read-up on buck converters, because that's the background information that you might be missing.

M3 provides synchronous rectification, which is an improvement on the basic buck converter in efficiency and heat dissipation. As M3 is turned on and off, the current through M3 would be the same as if it were a diode. However, the turned on MOSFET doesn't have a forward voltage drop of a diode.

Nick Alexeev
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  • Yes I have been meaning to read on these buck converters for some time. Thank you for the link. – Eae Jan 06 '15 at 03:20
  • I'm mainly a programmer not an EE. Laymans terms and for dummies explanations would really really help me. I really liked the source code for the project. – Eae Jan 06 '15 at 03:36
  • I seem to remember some talk about a body diode. If every circuit accounts for these things I should be able to figure out what's going on. I've been told the body diode can obstruct flow sometimes but in other times no. I though that http://everycircuit.com/circuit/6539292895608832 is a good buck converter. – Eae Jan 06 '15 at 05:06