Max232 capacitor placing issues

Thread Starter

Tinsae

Joined Jan 8, 2015
113
Dear all,
To communicate pc to atmega32 I googled and reached max232 circuit. The problem is in some schematics pin2 of max232 connected to gnd via cap but some connect it to vcc via cap also for pin 6 schematics are not the same. Following some schematics on the web I connected pin 2 of max232 to +ve of a cap and -ve of that cap to gnd. And pin6 to -ve of another cap and +ve of that cap to gnd. When I switch power on l7805 and this max232 got hot. So I decide to get solution from the forum please help. Snap shot of different schematic attached
 

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carloc

Joined Oct 8, 2018
13
After initial transient, capacitors will stop any DC flowing, so when one of its terminations is connected to 0V GND it can be otherwise connected to any DC voltage with no change in circuit behaviour.

So swapping GND with VCC goes unnoticed at first level analysis.

Of course a deeper insight soon shows possibly subtle differences which may or may not be worth caring of, upon different circuits and different performances specified

Capacitor working voltage may change together with polarity for electrolytic ones.

Noise consideration can also give different preferred connection point, many other related things could be worth an analysis.
 

Thread Starter

Tinsae

Joined Jan 8, 2015
113
Hi,
I use this circuit from the d/s, observe the caps polarity.
e
I think this image at least gave me some relief it say you can connect pin either to Vcc or Gnd via cap. That is fine but stil I dont know why the chip gets hot. I will trace it agaib
 

ericgibbs

Joined Jan 29, 2010
16,789
hi,
I always connect the cap on pin #2 to 0V, never had a problem.
What are the specs on the 1uF caps that you are using.?
E
 

Thread Starter

Tinsae

Joined Jan 8, 2015
113
Dear all
When I change pin 2 cap as follow it worked.
1uf/50v electrolytic cap negative terminal to pin 2 and gnd of the cap to vcc (5v)
Thank you all
 
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