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L298N Motor Driver Circuit Problem

Dear LMR,

For some reason I am really struggling with implementing a simple L298N motor driver. I have a simple breadboard robot and I am trying to run a Timya dual gearbox off the driver. I made a recommended circuit from the data-sheet but for some reason when I pull one of the inputs high (by connecting it to 5V power rail) the motor driver does not activate the motor outputs. I used an oscilloscope to measure all the voltages and everything is as it should be but for some reason the outputs always remain grounded. I could appreciate some help as I do not know what I am doing wrong. I have read forums related to this on LMR and have not found a solution. Bellow are pictures of the connections and the circuit. I have also attached the data sheet.


PS I have tried changing the L298N driver and I get the same result so it is not a case of the driver being fried.



Recommended Circuit


My Connections

SOLUTION (synopsis):

My setup worked when I used this schematic: http://www.solarbotics.com/assets/schematics/solarbotics-l298_schematic_complete.jpg

The original setup was wrong because Vss of 5v is needed for logic and Vs for motor power must be at least Vss + 2.5V. I was trying to use 5V for both. From my understanding this difference is necessary to bias the internal transistors of the driver.

Thanks to everyone who helped!

L298N-Motor_Driver.pdf190.37 KB

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Hi Gonzik,

Check the polarity of the diodes. I had the case that the marking on several diodes were wrong.

Checked the polarity, all the diodes seem fine. I tried replacing my diodes (rectifier diodes) with some schottky diodes I had laying around and still no response.

just give a try,.,.without diodes.,,., it will smoothly run.,.,

You can cross reference the schematic of my Bluetooth RC tank if you like.  Make sure you use two different supplies; Vss of 5v for logic and Vs for motor power that is at least Vss + 2.5V

You say you are pulling one of the inputs high, are you pulling the other one low at the same time?  I dont think your motor will turn if one of the inputs is left floating. 

Thanks I got it working. The solarbotics schematic is able to handle one input left floating though.

Solarbotics has a L298n breakoutish board http://www.solarbotics.com/products/k_cmd/

More interesting is the schematic: http://www.solarbotics.com/assets/schematics/solarbotics-l298_schematic_complete.jpg

Gonzik, do you using this schematic?

Hey Markus thanks for that schematic. I was able to get it working =) I am not sure what was wrong with the one provided in the data sheet. I have one thing I don't understand though. What is the purpose of the two 47K resistors? Is it to make sure that the enable input is not left floating at any point?

dude, did you get this working?