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Topic: L293D overheated but not burned !! what's the solution ? (Read 5 times) previous topic - next topic

firashelou

Aiming for the unreachable !


Runaway Pancake

#47
Jul 28, 2013, 08:05 pm Last Edit: Jul 28, 2013, 08:09 pm by Runaway Pancake Reason: 1

so about the piece of metal for heat sink, it should be connected with a wire to the pins ?


No, that will not work.  
Ideally, those pins (Gnd - 4, 5, 12, 13) should be soldered to a "ground plane", with the underside of the IC laying right on the copper of the "ground plane".  That's how the heat gets drawn out - mechanical, physical contact.
Barring that, any heatsinking will have, at best, only marginal effect.
I would not anticipate any marked result from clamping a piece of metal atop the IC.

The L293 is a #%@& IC that people expect too much from.

> > > Why is this being discussed in "Microcontrollers"?
"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

firashelou



so about the piece of metal for heat sink, it should be connected with a wire to the pins ?


No, that will not work.  
Ideally, those pins (Gnd - 4, 5, 12, 13) should be soldered to a "ground plane", with the underside of the IC laying right on the copper of the "ground plane".  That's how the heat gets drawn out - mechanical, physical contact.
Barring that, any heatsinking will have, at best, only marginal effect.
I would not anticipate any marked result from clamping a piece of metal atop the IC.

The L293 is a #%@& IC that people expect too much from.

> > > Why is this being discussed in "Microcontrollers"?


can you please show me an example on how to do it by posting a picture ?
i wasn't sure were to ask this question so i chose microcontrollers isn't it ?
Aiming for the unreachable !

Runaway Pancake


can you please show me an example on how to do it by posting a picture ?

I have attached ST's datasheet (PDF).
If you look at page 4 of 7 ("4/7") they depict [see "Figure 2"] the sort of board surface required.


i wasn't sure were to ask this question so i chose microcontrollers isn't it ?

I'm not "The Boss", but a L293D is a "four channel driver".
"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

firashelou



can you please show me an example on how to do it by posting a picture ?

I have attached ST's datasheet (PDF).
If you look at page 4 of 7 ("4/7") they depict [see "Figure 2"] the sort of board surface required.


i wasn't sure were to ask this question so i chose microcontrollers isn't it ?

I'm not "The Boss", but a L293D is a "four channel driver".


ok i saw the picture but i didn't get much what's going on there !! :(
Aiming for the unreachable !

Runaway Pancake


I'm sorry but I don't have a CAD package to render you an orthogonal view of the situation and it is beyond my artistic ability to draw it for you.

But, here's a link to Unitrode's datasheet, where they present (see Figure 10) the ideal ground plane vs. the IC outline.
http://www.zagrosrobotics.com/files/L293.pdf

A prototyper of any accomplishment could splay, or "un-bend", all of the pins [except the Gnd pins] out straight from the IC body and solder the Gnd leads to a piece of copper-clad board and then "dead-bug" (etc) all of the other connections from there.
"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

alnath



> > > Why is this being discussed in "Microcontrollers"?


yes, I was wondering too ...
should be in general electronics, I guess

firashelou



I'm sorry but I don't have a CAD package to render you an orthogonal view of the situation and it is beyond my artistic ability to draw it for you.

But, here's a link to Unitrode's datasheet, where they present (see Figure 10) the ideal ground plane vs. the IC outline.
http://www.zagrosrobotics.com/files/L293.pdf

A prototyper of any accomplishment could splay, or "un-bend", all of the pins [except the Gnd pins] out straight from the IC body and solder the Gnd leads to a piece of copper-clad board and then "dead-bug" (etc) all of the other connections from there.


aha ok i saw the figure 11, so the piece of metal should be mounter of a support on the top of the IC and touching the IC ?
if yes, then if i got a pice of metal and put it right there will that be good to get rid of heat or i must solder the GND to a bigger range ?
i am not working on a PCB but on a vero board
Aiming for the unreachable !

firashelou




> > > Why is this being discussed in "Microcontrollers"?


yes, I was wondering too ...
should be in general electronics, I guess


ok i am sorry about that :S
Aiming for the unreachable !

jack wp

I will put in my last 2 cents worth.
There is no one answer as to how to take away all the heat. There are many things that could be done to reduce the heat, such as: use a better IC, solder it onto a copper clad board, reduce the duty cycle, blow air across it, glue a heat sink on top of the IC, and the list goes on and on. I think we have about exhausted discussions on this little IC.

Jack
Good luck, Jack

firashelou


I will put in my last 2 cents worth.
There is no one answer as to how to take away all the heat. There are many things that could be done to reduce the heat, such as: use a better IC, solder it onto a copper clad board, reduce the duty cycle, blow air across it, glue a heat si
nk on top of the IC, and the list goes on and on. I think we have about exhausted discussions on this little IC.

Jack

yes so what I need to know. about is how to glue the heat sink above the ic?  if we put glue then it will act like a wall between the ic and the metal piece!  so how to do it?
Aiming for the unreachable !

jack wp

Here is one heatsink http://www.circuitspecialists.com/33hs016.html
And a google for "heatsink glue adhesive" finds several glues.

Good Luck, Jack
Good luck, Jack

firashelou


Here is one heatsink http://www.circuitspecialists.com/33hs016.html
And a google for "heatsink glue adhesive" finds several glues.

Good Luck, Jack

aha thank you, so I just have to glue it at the top of the chip which in the socket?
Aiming for the unreachable !

jack wp


You stated in your first post:
Code: [Select]
soldered pins : 1, 2, 3, 4,6,7,8
soldered just to the "PCB" : 9, 16


Now you have moved it to a socket?

It will really help to dissipate the heat if you solder it to the PCB, rather than using a socket.

BTW, why are you asking me which IC to put the heatsink on? You know the one that is overheated.
Good luck, Jack

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