Hai.,

i have made a MAX232 circuit followed by the datasheet and when i give power supply to the board the 232 IC heats up very high .,

https://datasheets.maximintegrated.com/en/ds/MAX220-MAX249.pdf

and i have connected 10uF SMD unpolarized capacitor to my board ...!
but in the data sheet it says to connect only the polarized cap.!

would that be the main reason for the heating issue?
or is there any other issue?

Thanks in advance.,
-saif

 

You have SMT non-polarized 10μf?
Normally this would not be a problem for a MAX232 IC.
There must be some other reason.
Max.

 

Hai.,

i have made a MAX232 circuit followed by the datasheet and when i give power supply to the board the 232 IC heats up very high .,

https://datasheets.maximintegrated.com/en/ds/MAX220-MAX249.pdf

and i have connected 10uF SMD unpolarized capacitor to my board ...!
but in the data sheet it says to connect only the polarized cap.!

would that be the main reason for the heating issue?
or is there any other issue?

Thanks in advance.,
-saif

It's been a while since I've used the original MAX232 chip, and I remember it got very hot when constant transmission of data was taking place. I've been using the (in my opinion) far superior MAX232A, which uses 0.1 uF caps. On the other hand, your diagram shows that you're using 10uF caps instead of the 1uF cap shown in the datasheet.

 

Non-polar capacitors are fine. Higher capacitance is actually usually better because the ripple voltage and hence ripple current is lower resulting in less loss in the switches in the charge pump. The average current doesn't change, but the the RMS does and that is what matters since the pump switches are essentially resistors when ON.
You should have a decoupling capacitor across the supply for the MAX as close as possible.

Beware of very large negative voltage coefficient of capacitance with ceramic capacitors with very high dielectric constant. X5R and X7R are not too bad but Y5V and Z5U and similar types are terrible. However, since you have more capacitance than really required, this should not be problem even if you are using the "bad" types.

 

@saifudeen rizal Did you try it with the I/O port disconnected?
Max.

 

Pin 9 and 10 were wrong, they should be exchange as Pin 7 and 8, OUT pin connected to the Tx, IN pin connected to Rx.

 

@saifudeen rizal Did you try it with the I/O port disconnected?
Max.

Hai .,

The IC simply heats up on giving power supply itself..!

-saif

 

Pin 9 and 10 were wrong, they should be exchange as Pin 7 and 8, OUT pin connected to the Tx, IN pin connected to Rx.

https://www.google.com/search?q=max...8KHdeMAuIQ9QEwAXoECAIQBg#imgrc=CbecjB043l1XXM:

I think my connection are correct...!scott..!

-saif

 

Non-polar capacitors are fine. Higher capacitance is actually usually better because the ripple voltage and hence ripple current is lower resulting in less loss in the switches in the charge pump. The average current doesn't change, but the the RMS does and that is what matters since the pump switches are essentially resistors when ON.
You should have a decoupling capacitor across the supply for the MAX as close as possible.

Beware of very large negative voltage coefficient of capacitance with ceramic capacitors with very high dielectric constant. X5R and X7R are not too bad but Y5V and Z5U and similar types are terrible. However, since you have more capacitance than really required, this should not be problem even if you are using the "bad" types.

hai.,

i have checked by connecting a 10uf decoupling capacitor across the supply for Max but it heats up like it used to.,!

-saif

 

https://www.google.com/search?q=max232+schematic&client=ubuntu&hs=ZKz&channel=fs&tbm=isch&source=iu&ictx=1&fir=CbecjB043l1XXM%3A%2CneV0lf8HhlCRJM%2C_&usg=AI4_-kTDHsz9aBZkCGN1HvfqSOkYPvIBsA&sa=X&ved=2ahUKEwirtdqi8KXeAhWBL48KHdeMAuIQ9QEwAXoECAIQBg#imgrc=CbecjB043l1XXM:

I think my connection are correct...!scott..!

-saif

Sorry.
Yes, your connections are correct, your direction is different from mine, I already get used to put the 9 pin connector on the left side of the circuit, although I had been compared the circuit with mine last night, but I still messed with the direction.

 

hi ,
Measure the voltages on pins #2 and #6 of the MAX, post what you measure.
E

 

hi ,
Measure the voltages on pins #2 and #6 of the MAX, post what you measure.
E

Hai Eric.,

The Voltage across the 2nd pin is 4.06 V and Across 6th pin it is 2.45 V (MAX).,

-saif

 

hi,
That is low, I usually get +/-8v minimum.
One should be a negative voltage ie: pin #6
Do you have a replacement MAX to try.?
E

 

I'm not sure what you mean when you say "voltage across a pin". I think Eric asumed that you have more electrical knowledge than you do as you list your occupation as electrical engineer. He would have meant measure the voltage ON those pins with respect to ground (Pin 15) Can you measure the voltage again on these pins with respect to ground (Pin 15). Also measure the voltage on pin 16 with respect to ground. Pin 2 is the output of the positive charge pump which should be at a little less than + 10 volts. Pin 6 is the output of the negative charge pump which should be a little less than - 10 volts.

Les.

 

I'm not sure what you mean when you say "voltage across a pin". I think Eric asumed that you have more electrical knowledge than you do as you list your occupation as electrical engineer. He would have meant measure the voltage ON those pins with respect to ground (Pin 15) Can you measure the voltage again on these pins with respect to ground (Pin 15). Also measure the voltage on pin 16 with respect to ground. Pin 2 is the output of the positive charge pump which should be at a little less than + 10 volts. Pin 6 is the output of the negative charge pump which should be a little less than - 10 volts.

Les.

Hai Les.,

" I think Eric asumed that you have more electrical knowledge than you do "
i am here to seek a solution for my problem, just avoid this kind of talk and try to help me .,
and i am not that much dump so please.,



and for ur info.,
The Vcc is 5v.
voltage across the V+ & V- is 4.06V and 2.45V
-saif

 

hi,
That is low, I usually get +/-8v minimum.
One should be a negative voltage ie: pin #6
Do you have a replacement MAX to try.?
E

View attachment 162512

I am working on this eric will reply u in short time

-saif

 

Hi saif,
voltage across the V+ & V- is 4.06V and 2.45V

We want to know the voltages from pin 2 and 6 measured to 0v /Gnd.???
E

 

Could you measure the draw current and the resistance of the IC?

 

hi,
That is low, I usually get +/-8v minimum.
One should be a negative voltage ie: pin #6
Do you have a replacement MAX to try.?
E

View attachment 162512

Hai eric.,

I have changed the Max IC and now its coming around 9.2V ...!
9.2 V is normal right?

and thanx for helping eric.,
and by the way i have one query?
is decoupling capacitor is really necessary for this IC?

-saif

 

Hi saif,
voltage across the V+ & V- is 4.06V and 2.45V

We want to know the voltages from pin 2 and 6 measured to 0v /Gnd.???
E

View attachment 162515

That is what i measured and replied to u.,

The fault is on the IC .,I have changed it and now the voltage comes around 9V..!

-saif