L293d

[kambliarup]

We have made a circuit for RF controlled car. We had used a L293D IC chip and four 12V DC supply motors. But the IC overheated and burned. Please help...
Can we use any other IC in place of it to avoid overheating or can we cascade 2 L293Ds?

 

[philba]

before you start replacing the chip, you should figure out what kind of current draw you've got.

did you follow the datasheet on layout and heatsinking? the dual inline package doesn't have the greatest heat dissipation ability. You might want to look at the L298.

since you are using 4 motors with one L293D, I'd think using seperate MOSFETs would be a better idea as you can select one for as much current as you want. No sophisticated controls needed - I don't think you are even using PWM because the 293 has one enable per 2 half bridges.

 

[kambliarup]

Are the specifications of L293D and L298 same? Which one would you suggest L298 or using mosfet?

 

[philba]

It depends on the motor current. what is yours?

no the L298 and and 293D are different. look at the datasheets.

 

[kambliarup]

current drawn per motor is 0.8 Amperes.
which ic is preferable? plz consider the complexity and cost

 

[audioguru]

The motor driver IC must be rated to continuously pass the motor's max current. The motor's current is at its max when it starts and when it is working very hard when stalled and when its direction is changed too quickly.
I bet your motors use a lot more than only 0.8A when they start.

The L293D is rated for only 1.2A for a moment. It is spec'd with only 0.6A which makes weak ones hot.

 

[philba]

I agree with AG. L293 isn't going to do it. also, the L293 isn't a very good package for heat dissipation, especially if you don't use a layout similar to the recommended one in the datasheet.

use the L298. read the datasheet carefully and don't forget the diodes or a heat sink.

 

[picasm]

There is a TI equivalent to the L293 - the SN754410 which is rated at 1A, the L293 is only 600mA.
You still need to use a heatsink though.
It is possible to bridge two together by soldering one on top of another (both need heatsinks).
I found a good comparison and info on this site:
https://www.kronosrobotics.com/an101/AAN101.shtml

The SN754410 can be more expensive than a L293D so I would agree with philba that it would be better to use a L298 which is about the same price as a L293D and has a better heatsink (on the multiwatt15 package) and handles 2A easily.

So far, the cheapest web site that I have found these on is Futurlec
(www.futurlec.com) - but I have never bought anything from them - so don't
know what their service is like.

 

[philba]

I've seen the piggy-back L293 before but can't help think it's a poor solution as it is a bipolar device and won't share current equally. Plus, it wont dissipate anywhere 2X the heat.

Note that the spec'd current is all about heat dissipation (ok, almost all...). If you can't get rid of the heat, the chip dies. You should try to understand how much heat your application will generate - I'd guess around 1 watt per motor for 4 watts total. (4 * 1.2V * .8A) I don't think a dip or two, even with a heatsink, is going to cut it. Use the L298 with a sink...

Jameco has L298s for less than $3.