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Topic: L293D overheated but not burned !! what's the solution ? (Read 6135 times) previous topic - next topic

firashelou

Jul 25, 2013, 11:07 am Last Edit: Jul 25, 2013, 11:19 am by firashelou Reason: 1
hello guys,
check the attachment file please, this is the circuit i just build for the L293D
i was trying it, it works fine but the IC got overheated :S so what might be a solution for this ? and what's the reason ? is it because of the capacitors or it's just normal ?
i am using a 12V motor of an RC car and feeding the IC with a 12V current from VCC1 connected to 12V + and the pin4 GND connected to - of the 12V
when trying it on breadboard there was no overheating

soldered pins : 1, 2, 3, 4,6,7,8
soldered just to the "PCB" : 9, 16
blank pins : 10 to 15  
Aiming for the unreachable !

Grumpy_Mike

Try a ceramic 0.1uF cap across the power supply to the chip it might be oscillating.

firashelou


Try a ceramic 0.1uF cap across the power supply to the chip it might be oscillating.


so i remove the 100 uF and put a 0.1uF ceramic cap instead ?
Aiming for the unreachable !


firashelou

#4
Jul 25, 2013, 11:24 am Last Edit: Jul 25, 2013, 11:36 am by firashelou Reason: 1

No have them both.

ok Thank you Grumpy Mike :)

Aiming for the unreachable !

firashelou

it's still getting over heated but now it take a bit more time to get there !! :S
Aiming for the unreachable !

Grumpy_Mike

Quote
but now it take a bit more time to get there

Sounds like it is supply related.
The next step would be to look at the signals on an oscilloscope but I guess you don't have one.

So you are just shooting in the dark.
Some shots you could make is to see if things improve with the wires as short as possible. Add a series inductor ( as big as you can get ) in line with the high voltage positive supply to the chip.

firashelou


Quote
but now it take a bit more time to get there

Sounds like it is supply related.
The next step would be to look at the signals on an oscilloscope but I guess you don't have one.

So you are just shooting in the dark.
Some shots you could make is to see if things improve with the wires as short as possible. Add a series inductor ( as big as you can get ) in line with the high voltage positive supply to the chip.


aha ok this is like your schematic
but now the chip is getting better the heat is supportable not very hot but of course every step for more safety is great
Aiming for the unreachable !

cabbagecreek

This could be a Diod problem. The diods for a L29x needs to be FAST recovery diodes. If one of them is not fast enought (=fried or faulty) the PWM will produce a backcurrent that is deadly for the L29X. (= get fried because of heat). The process when that this is happening is FAST and results in fire and almost explosion. I have a coule of fried L298N  :~

I use 24V to a L298N and when it fries it connect the IN1-4 on L298N with 24V -> Arduini digatal pins. This have fried my Arduino UNO a couple of times. I found a optocoupled L298N on ebay. A bit more expencive but alot cheaer than the Arduino UNO.



firashelou


This could be a Diod problem. The diods for a L29x needs to be FAST recovery diodes. If one of them is not fast enought (=fried or faulty) the PWM will produce a backcurrent that is deadly for the L29X. (= get fried because of heat). The process when that this is happening is FAST and results in fire and almost explosion. I have a coule of fried L298N  :~

I use 24V to a L298N and when it fries it connect the IN1-4 on L298N with 24V -> Arduini digatal pins. This have fried my Arduino UNO a couple of times. I found a optocoupled L298N on ebay. A bit more expencive but alot cheaer than the Arduino UNO.



now it feels better for me when i took the advice of Grumpy Mike, results are better, the IC get hot but not overheated when i use it for a long time
amazing !!
Aiming for the unreachable !

MAS3

Do you read datasheets ?
The device is supposed to be mounted on at least a copper surface of certain size for heat dissipation.
The datasheet is clear about that, it's shown on top right part of page 1.
A vero board (as you are using) doesn't do this for you, so you have to think of some other way to get it cooled.

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.

The diodes cannot be incorrect types, because they are integrated and have been so for 27 years.
A device will not last this long if it has such design flaws.
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


Do you read datasheets ?
The device is supposed to be mounted on at least a copper surface of certain size for heat dissipation.
The datasheet is clear about that, it's shown on top right part of page 1.
A vero board (as you are using) doesn't do this for you, so you have to think of some other way to get it cooled.

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.

The diodes cannot be incorrect types, because they are integrated and have been so for 27 years.
A device will not last this long if it has such design flaws.


i do read datasheets for sure but i don't understand everything, i mean just the basics

no i didn't say the diodes are not right, i was asking if it is necessary to put more diodes connected to the IC

by the way there is 2 pins which are Ground and heat sink, what do they mean heat sink where do you have to connect that pin to make the chip cool down ?
Aiming for the unreachable !

Grumpy_Mike

Quote
what do they mean heat sink

This is the place where you can attach some metal to help get rid of the heat from the chip. If you have a PCB then you can use a patch of solid PCB track to help cool the chip, or you can clamp an extra piece of metal onto it.

MAS3

Quote

no i didn't say the diodes are not right, i was asking if it is necessary to put more diodes connected to the IC

by the way there is 2 pins which are Ground and heat sink, what do they mean heat sink where do you have to connect that pin to make the chip cool down ?


I didn't react to you about the diodes.
Someone else said this could be a diode problem, but that is very unlikely and i tried to explain this to the both of you.

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.
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


Quote
what do they mean heat sink

This is the place where you can attach some metal to help get rid of the heat from the chip. If you have a PCB then you can use a patch of solid PCB track to help cool the chip, or you can clamp an extra piece of metal onto it.


aha ok so it's either a heat sink (attached to piece of metal) or attached to GND right ? both can take any function of these 2 ?
Aiming for the unreachable !

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