L298N motor driver

[yovenim]

Hello,

For our profile paper at school, we are building a football robot that can participate in the RoboCup Junior.

We use three motors for the drive, these motors have a 'free run' current of 300mA and a stall current of 5A. It is unlikely that the motor will draw such a high current because it is blocked,

but we still want to be sure that this high current does not damage our ICs or burn them out completely.

We would like to use the L298N for the engines. This has so-called sense pins, as long as these are not connected to GND, the IC does nothing at all.

It also turns out that you can use these sense pins to 'switch off' the IC as soon as the current becomes too high.

Unfortunately, I have not yet discovered how exactly this should work, does anyone have experience with this?

 

[KlausST]

Hi,

did you read the datasheet?
Post a link to the datasheet here (.. dirctly to the manufacturer´s internet site)
Tell us what is clear so far and what is not clear.

Also tell important things like motor voltage rating, power supply voltage (range)

Also tell other electrical informations/requirements that are important especially for your application.

And please draw a sketch. Using pencil and paper at least and add there all the informations. It helps us a lot to understand your situation.

Klaus

I´ve recognized a probably fake link in the copy of your post. Moderators should investigate it.

 

[BradtheRad]

Embedded link to commercial website is now deleted. Perhaps data specific to the L298N can be posted? Components that tolerate 5A should be more robust than those handling 300 mA.

 

[danadakk]

https://www.st.com/resource/en/application_note/an240-applications-of-monolithic-bridge-drivers-stmicroelectronics.pdf

A basic approach is using the sense resistor and feeding that to a RRIO comparator
which then drives the enable pin. The comparator also has the compare input to
a Vref, such that when Vsense > Vref the comparator disables the L298.

That would be a simple approach. Use a comparator and implement hysteresis to
reject noise from tripping the comparator. Also choose one with an onboard Vref
to make life easy.

Some possibilities :

https://www.digikey.com/en/products/filter/comparators/692?s=N4IgjCBcpgDArFUBjKAzAhgGwM4FMAaEAeygG1wQiAmEAXSIAcAXKEASQDtm8BzPAE4gAvkTAAOAMxIQqSJlyES5EABZqYAOzwIDECzYBlZgICWnXiNEhakCsmIBbRhgEZmxIXWFA

Regards, Dana.

 

[tepalia02]

You can see here for a better explanation about the sense pins: https://forum.arduino.cc/t/l298-current-sensing-how-does-it-work/153767/6

 

[D.A.(Tony)Stewart]

Is this for high school?

The L298N has a voltage drop of approximately 2V. This is due to the fact that internal switching transistors have a voltage drop of approximately 1V when forward biased, and because an H-Bridge requires the current to pass through two transistors, the total voltage drop is 2V.

This means your stall current resistance or DCR = Vcc/5A will reduce by 2V. Current sense resistors will raise this voltage and thus reduce torque, so if you this is important, use an Op Amp to amplify the voltage drop on external Rs with say 0.5 s rise time RC filter for feedback to allow quick acceleration that decays with the voltage rise to reduce PWM duty cycle in both directions.

Use the boards for ease of application, heat must also be dissipated with at least 10 cm^2 surface area on fins per Amp for cooler operation.

Test methods here for either Steppers or brush motors. Chose motors and wheels with RPM or speed for desired max acceleration or max speed which are tradeoffs.

In-Depth: Interface L298N DC Motor Driver Module with Arduino

Learn about L298N Motor Driver module along with PWM, H-bridge Working, Pinout, Wiring, Arduino Code for controlling speed & direction of DC motor.

lastminuteengineers.com

Heat rise must be expected and estimated to meet reliable limits not to burn fingers.