Electronics > Projects, Designs, and Technical Stuff

USB charger circuit for car

<< < (4/8) > >>

madires:
The TVS goes between Vcc and Gnd, like a Zener. Simply put it in parallel with C1. 15V could be a tad low. I'd suggest 18V.

mariush:
If you want to learn something, use a MC34063 switching regulator to get your input voltage down to 5v, or down to around 6-7v and then down to 5v using a linear regulator
Plenty of documentation for it in datasheets (the chips are made by various companies, just download several datasheets and look at the instructions, notes etc in them),
there's online calculators for parts : http://www.nomad.ee/micros/mc34063a/  and  https://www.electronicproducts.com/DC-DC_Circuit_Calculator.aspx
and even software for it for ex. https://sourceforge.net/projects/mc34063uc/ 

All parts are cheap and can be bought from TME and others... all through hole... My advice would be design it for 11v..14v input, 6v output  and then use a linear regulator to get 6v down to 5v

With 34063, you'd get up to around 0.75A of output current... here's an example:



The inductor value is odd, but it's a minimum - you can use slightly higher value, for example in this case 27uH or 33uH would be super common and standard values, bigger may mean slightly lower efficiency but you don't care about this. The hardest part to get would probably be the 0.12 ohm resistor for Rsc, but you can obtain it using two or three resistors in parallel ... for example you can use 2  x 0.22 ohm in parallel which gives you 0.11 ohm which is close enough

Then just get a 5v Linear regulator with a voltage drop lower than 1v at 0.75A ... for example LM2941 ... or loads of other regulators out there which are cheaper.

You still learn a lot and make your own circuit, but you don't have as big of a heat issue (you'll only have to dissipate 0.75w - 1v at 0.75a max)

Charybdis:
Thank you so much my friend mariush !!
Unfortunately as for now I'm not so skilled to fully understand everything.
But i truly apreciate your post :)

Charybdis:
Sorry to bother you, Madires. But do you think that this will be fine ?
I changed the diode and left the other 3 normal. Is it ok now ?
Thank you very much

madires:
Yep!

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod