I'm making a rover where I have two 3.7v li-ion batteries as a power supply. Is it better to power the Arduino Uno directly with these batteries or should I power it with l298n's 5v regulator? Please also explain which pin of the arduino I should feed.
Please don't recommend a different motor driver unless you believe that I can't do it with a l298n, I'm on a budget.
Both ways look possible. Do You have any other 5 volt loads?
The 5 volt converter on the UNO is very limited, barely enough for the UNO. An LED or two is maximum load.
Check the datasheet for the L298N and its 5 volt converter! Maybe it has a little bit higher capacity.
It also depends a lot on the voltage and amperage requirements of the motor or controller you're using. You can't power the motors directly from the UNO regardless of how they're wired. What are your plans on that front?
On a good day you will get about 4.6 volts on the motor terminals with a 7.4V supply. Before purchasing the L296N (bipolar technologie) you should have looked for a MOSFET output bridge. The losses through the MOSFET would be about 0.2V. The L298N has bipolar transistors in a darlington configuration on each side so you will lose about 1.4V through each pair or about 2.8V in total that will just be burnt up as heat. Rule #1 "A Power Supply the Arduino is NOT!"
I plan on having the Arduino control the l298n and power a sg90 servo, a buzzer and a hc06 bluetooth module. So that's probably too much. Apparently l298n's 5v regulator has a maximum output current of 500 mA. sg90's stall current is 650 mA so that's not enough either.
My plan is to power the L298n which is driving two small 6v dc motors with 7.4v. Then I will either connect the batteries to the Uno's barrel socket or Vin pin or power it with the L298n's 5v regulator. I also plan on having the Arduino power a sg90 servo, a buzzer and a HC06 bluetooth module so there should be enough current fed into it for that.
Does L298N have a regulator?
The IC itself should be fed with 5V on the 5V pin (used by the controller inside) and a higher voltage on the pin that feeds the motor(s).
The 5V should be regulated. The other does not really matter.
You might have a board with a regulator... ...share a link to the datasheet so we can check...
If the voltage of the battery drops below 7 or so (when the battery is almost empty), the regulator might not be able to produce 5V.
Good chance that your arduino will run fine on 4.5V, but no guarantees...
Correct. You need more current.
Regard the posts warning You for using that voltage wasting L298...
Don't power things like that from an Arduino. The tiny copper strips on the board will not manage.
Yes.
The joy it board seems to have a 5V regulator. ... it is not part of the IC. There are also boards without a regulator.
Are you sure about that? The Arduino Uno has a SPX1117M3-L-5 regulator, which has an output current of 800 mA and a peak current of 1A according to this datasheet. If that's true it's definitely enough.
Have you looked up the max heat dissipation? If you feed it with 12V you cannot have 800mA...
5V times 800mA is 4W. The regulator will overheat really fast.
YES!
I don't know from where You got that data. Regard that the power dissipation heavily depends on the voltage at the input. Voltage converters often need heatsinks, and fans. A TO220 can dissipate 1W but the UNO board controller is not a TO220, has no fan and has much smaller cooling surface.
If You don't believe that, just go ahead, try it and make toast of things.
Thanks for the replies, I realized that both of my initial solutions are undesirable so instead of using the L298n or the arduino’s linear regulators I’m going to use a LM2596 Buck converter board like the one in the image which should get rid of the overheating and the low amp problem.
Now that I have fully assambled and tested the entire circut, the buck converter wasn't really that necesarry. The Arduino's voltage regulator could supply enough current and didn't get hot at all and neither did the L298N. Unless you want your circut to operate for long hours, just use the Arduino's regulator.
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