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Topic: L293D overheated but not burned !! what's the solution ? (Read 6130 times) previous topic - next topic

firashelou

#15
Jul 26, 2013, 12:44 am Last Edit: Jul 26, 2013, 12:46 am by firashelou Reason: 1

And no, there's 2 * 2 pins that are labeled GND and Heat sink.
As Grumpy_Mike explained a custom PCB can be made to act as heat sink (within limits).
A vero board can not, because it has no large piece of copper, just a lot of very small pieces.
Therefore a vero board will do a very poor job at this.



and if i attached a piece of metal to it, it won't work 2 ?

if there is no solution for this other than capacitors and inductor as suggested Grumpy Mike then what i can do is to put a temperature sensor which can tell me the temperature so when it gets close to 60 degrees to 70 degrees then a buzzer will make a buzz so i know that i must turn the system off and it will be safe then !!
Aiming for the unreachable !

firashelou

hey guys, because my projecg is around an rc f1 car so I just noticed that I can use the body of the car to cool the chip down, better than leave it like this, I can put it on one of the sidepods, the chip will be in a perpendiculaire line to the ground, the whole circuit of it will be so do you think this will effect anything any function or the position doesnt matter if we're talking electronics ? because physically the chip we'll be getting the maximum air,,, threw the hole of the sidepod
Aiming for the unreachable !

MAS3

These 4 pins are both GND and heat sink, not either one.
Use all 4 to have a more efficient path to get rid of heat.

Buzzer that makes you turn it off ?
Why not have the Arduino handle this by taking action in case of overheating, it's available right there.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

MAS3

Are those sidepods functional ?
Very unlikely.
If the body is metal, you can use that for heat dissipation.
But if you connect it directly, then you have GND on the body of your car and need to remind that.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

firashelou


These 4 pins are both GND and heat sink, not either one.
Use all 4 to have a more efficient path to get rid of heat.

Buzzer that makes you turn it off ?
Why not have the Arduino handle this by taking action in case of overheating, it's available right there.


so i connect the 4 pins to GND that's an idea
and about the buzzer, what i mean here is that the buzzer will give you a signal so you know that you must be carefull
and maybe i can put a display that will give me the temperature of the chip captured by the sensor
Aiming for the unreachable !

firashelou


Are those sidepods functional ?
Very unlikely.
If the body is metal, you can use that for heat dissipation.
But if you connect it directly, then you have GND on the body of your car and need to remind that.


actully the car is sort of plastic but the sidepods has a hole so i can make them functional which means, so they won't just be for the shape of the car but to give a bit of cooling for the IC
Aiming for the unreachable !

MAS3

The sidepods only work if you are making some speed.
That will not be optimal so keep looking for a way to cool stuff.

Connect 4 pins to GND and make sure that you have an as large as possible surface around the pins.
That way that GND surface doubles as a radiator (sort of).
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

oric_dan

OP, I may have missed it, but I didn't see anyone asking you how much current your motors draw. ???

MAS3


Do you read datasheets ?
...
Directly next to that on the left side, the datasheet tells you the device can handle 600 mA.
Earlier you were asking about H bridge drivers for over 1 A.
...
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

oric_dan

Not sure what the previous post is about, but it doesn't answer my question, and which should have been the VERY FIRST thing that OP found out about. You can't get anywheres if you don't know how much current the motors draw. 12V motors - could be 250 mA or 5A, etc.

jack wp

Has anyone ever tried a heatsink on top of the IC, like this one ?
http://www.circuitspecialists.com/33hs016.html
I would suspect it would have to be attached with heatsink glue.  I have not tried it, but looks like it would be a lot of help if the IC is getting to hot.
Good luck, Jack

oric_dan

#26
Jul 26, 2013, 08:32 pm Last Edit: Jul 26, 2013, 08:40 pm by oric_dan Reason: 1
Yeah, they sell several heatsinks for these sort of chips.
http://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1028&bih=849&q=dip16+heatsink

http://www.jameco.com/1/1/532-501200b00-heat-sink-passive-dip14-dip16-straight-extruded-epoxy-68-c-w-black-anodized.html

They help somewhat, but you can't expect miracles with an L293D. Being a bipolar device, there is a typical 1V to 1.5V drop across the output transistors [see the datasheet], so "worst case" for 4 channels would be

Pd = 4 * (1V to 1.5V) * 0.6A = 2.4W to 3W,

and even with the better heatsink cited, the temperature rise would be on the order of

(2.4 to 3W ) * 46ºC/W = 110ºC to 138ºC. Pretty darn hot. Varies, of course, with fewer channels and less current.

MAS3

@oric_dan:

OP has a lot of threads going on at the moment, and they all come to a certain point where he seems to just gather some stuff together and is trying to make it work without understanding a bit.
So he asks questions but always without enough information.
There is an other thread where he asked about controlling a > 1 A motor for his model car and the next day he started this thread.

He has told he does read datasheets but doesn't understand all of it.
I guess English isn't his first language too, complicating things.
But i've never seen him asking questions about things he doesn't understand in datasheets.
He does ask after buying parts, putting them together and gets stuck after that.
If it takes over 3 days to understand, he just gives up to start over with an other approach or part for the same project.

It is very hard to help OP because of all of this, and i really tried.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

jack wp

OK, to answer the original question "L293D overheated but not burned !! what's the solution "

Don't touch it if it is to hot !
Good luck, Jack

oric_dan

Quote
It is very hard to help OP because of all of this, and i really tried.

Ok, I understand, hadn't seen the other threads. I just noted the most fundamental info was missing in "this" thread, :-(.

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