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Topic: MAX3232 Wiring with Capacitors (Read 1 time) previous topic - next topic

Qtechknow

Hi everyone,
I was looking up parts for a project of mine, and ran into the MAX3232 IC.  It can be found at Sparkfun, http://www.sparkfun.com/products/589, with the datasheet.  I know that this needs 4 0.1uf capacitors, but I don't know where, and I don't know if I need electrolytic or monolithic.  Any help?

Thanks,
Qtechknow

Graynomad

I've always used tantalums, as to where they go, there are a 1000 example circuits around and the data sheets always have them as well, does your data sheet not have a circuit?

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

Nick Gammon


I know that this needs 4 0.1uf capacitors, but I don't know where, and I don't know if I need electrolytic or monolithic. 


The page said:

Quote
Requires four external 0.1uF ceramic capacitors ...


I hope that helps.
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

majenko

You can read the "0.1uF" as "100nF" and suddenly you think "Ah - I have thousands of those here - I use them for power decoupling!" and the lightbulb switches on.

James C4S


I know that this needs 4 0.1uf capacitors, but I don't know where, and I don't know if I need electrolytic or monolithic.  Any help?


Pages 6 and 7 of the data sheet shows where to put them.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

Qtechknow

In the schematic and wiring in the datasheet, it shows that the caps are polarized, implying that they are tantalum or electrolytic.

shelleycat

#6
May 26, 2012, 07:15 pm Last Edit: May 26, 2012, 07:17 pm by shelleycat Reason: 1
No, it shows the way the voltage will be applied across the CERAMIC capacitors.

My data sheet says "The type of capacitor is not critical for proper operation.  Ceramic capacitors are suggested... If polarised capacitors are used....(and then goes on to explain what to do)

James C4S


In the schematic and wiring in the datasheet, it shows that the caps are polarized, implying that they are tantalum or electrolytic.

Tantalum is an electrolytic.  ;)  Though I think you meant Aluminium Electrolytic.

"I would read that as, if a polarized capacitor is used, make sure it is connected this way."    The section "Capacitor Selection" on page 13 does explain why the caps are used and what values to pick.

The short answer is, if you use ceramic use something bigger than what is suggested.  If you use an electrolytic, don't connect it backwards.

Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

Qtechknow

I think I'm going to go with ceramic (non polarized).  What value should I use?  Could I connect two 0.1uf caps in series for each "capacitor placement"?

Qtechknow

James C4S, should I connect a 1uf (higher value) monolithic (non-polarized) capacitor instead of the electrolytic cap?

majenko

Quote
Could I connect two 0.1uf caps in series for each "capacitor placement"?

No, that would give you 0.05uF.

You can connect them in parallel to give you 0.2uF - they sum up in the opposite way to resistors.

Personally, I just stick to 0.1uF (100nF) ceramic as I have hundreds of them.  I don't have any problems.

Qtechknow

Thanks everyone for the answers!

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