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Topic: Can L293D really be put in parallel? (Read 3034 times) previous topic - next topic

electricviolin

Should I try to flip the signal wires or something (so that the bottom of the IC is getting the signal the top used to and vice versa). I am thinking I can then see if the bottom of the IC gets hot. I am assuming I would also have to flip the output wires then as well?
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

cr0sh

Can the L293 be used in parallel?

Well - as you've found, people have said they've done it with no ill effects...

That said, realize this: If the L293 could be used in such a manner, don't you think it would be mentioned in the datasheet? The fact that it isn't, is a big clue...

Here's the deal: The L293 is a bipolar transistor logic device. As such, you are not supposed to parallel such devices together normally - mainly because the devices won't generally share the load equally, and you'll get an unbalanced circuit, overload, then burnout of one or both devices.

The only way around this, is how the L298 is constructed - if you read the datasheet for the L298, you'll find that it is composed of two independent h-bridge drivers (for a single bipolar stepper, or two separate DC motors) - and that those drivers can be paralleled to allow you to drive a single DC motor. Even though the L298 too is a bipolar transistor based device, it has one important characteristic over the L293: Both drivers (well, actually the transistors which make up the drivers) share the same die. As such, they are highly matched in spec (having been essentially built at the same time), plus by sharing the same die, thermal differences are minimized, and are balanced. Now - you can't parallel two separate L298 ICs - so don't try that...

So - if you want to have a snowball's chance of this working (and there would still be no guarantee) - first make sure that both of your L293 ICs come from the same manufacturing batch. The best way to do this would be to purchase a factory sealed tube of the ICs - any two of the ICs sequentially should be very close to each other in spec. You might also be able to grade the devices with a testing rig, so as to determine which match closes to each other in operating characteristics.

Then - mount them both piggyback style, with some kind of copper strip between each pair, some heatsink grease or tape or putty - and make sure everything is tight together. Solder all of the legs together. Add a heatsink to the upper IC (more paste, etc) - then connect both sinks together (if using copper strips, use copper bolts - if aluminium - use aluminium bolts). You might want to also force cool them with a fan. The idea here is to basically heatsink them in such a way so that they will share the heat output load as much as possible. It isn't as ideal as being on the same die, but it is as close as you can get with these chips.

Don't be surprised though, if despite a ton of hard work, if none of that works or helps.
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

electricviolin

I think I am going to stick with the method mentioned previously as it seems to sort of be working.
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

raschemmel

The L298 modules are cheap enough that it really isn't worth the trouble to mess around with L293s when you need more current.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

electricviolin

I am assuming I would have to use a heat sink and diodes with it?
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

raschemmel

#35
Aug 03, 2015, 04:50 pm Last Edit: Aug 03, 2015, 04:50 pm by raschemmel
The L298 modules have all that already.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

electricviolin

I am eventually going to put the whole project on a printed PCB, so I am going to remake the circuit if needed rather than using a module.
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

raschemmel

If you use the L298 you need a heatsink or it will burn up as soon as you apply power.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

MAS3

You also need the diodes,they aren't present in the "chip".
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

raschemmel

Quote
You also need the diodes,they aren't present in the "chip".
Quote
The L298 modules have all that already.
Why don't you just get a module and mount it with standoffs and make an interface cable to connect to your arduino circuit ? Why would you try to make your own L298 pcb when you can get it premade so cheap ?
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

electricviolin

True, okay Ill see what I can do - thanks for all the help!
"To invent, you need a good imagination and a pile of junk" -Thomas Edison

eGuru

#41
Aug 20, 2017, 02:32 pm Last Edit: Aug 20, 2017, 02:37 pm by eGuru
(VCC2) Pin 8 go to 12V
(VCC1) Pin 16 go to 5V
(1,2EN - 2,3EN) Pin 1 - Pin 9 go to 5V
(IN 1 - IN 4) Pin 2 - Pin 15 go to logic 1
(IN 2 - IN 3) Pin 7 - Pin 10 go to logic 2 (opposite of logic 1)
(OUT 1 - OUT 4) Pin 3 - Pin 14 go to coil side 2
(OUT 2 - OUT 3) Pin 6 - Pin 11 go to coil side 1
(GND) Pin 4 - Pin 5 - Pin 12 - Pin 13 go to GND
The above is incorrect for the L293D.
If you look at the L293D pinouts, you will notice that the order of the functions of pins 9 to 16 are a mirror-image of 1 to 8.
So what you need in order to parallel the device is:
(VCC2) Pin 8 connect to 12V
(VCC1) Pin 16 connect to 5V
(1,2EN - 3,4EN) Pin 1- Pin 9
(GND) Pin 4 - Pin 5 - Pin 12 - Pin 13


(1N 1- IN 3) Pin 2 - Pin 10
(IN 2 - IN 4) Pin 7 - Pin 15

(OUT 1 - OUT 3) Pin 3 - Pin11
(OUT 2 - OUT 4) Pin 6 - Pin 14

The cross-over wiring is not that "tidy" but it will work.

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