1
\$\begingroup\$

I have an L298N motor controller module, rated at 5 amps. I'm using it to control two 12 volts linear actuators, and I'm using a current sensor per motor to learn when the motors have reached a high current load (~2.26 Amps) then stop them once they reach that threshold.

One of the actuators shaft bent on an accident, and now it requires 3.4 Amps (instead of the 0.9 Amps "no load" current) to move. The thing is that the current draw never goes above my threshold, as measured by my current sensor (therefore, the actuator never moves when a signal is sent). But now the channels (Out 1 and Out 2) on the L298N where the bent actuator was connected to don't work properly:

when nothing is connected to those two channels, I read and output closed to 12V. 
But as soon as I plug in any motor on those two channels 
(whether good or bad), those channels send 0V.

What exactly could have caused the failure of these channels? And is it a short that might have happened and something burned?

\$\endgroup\$
  • \$\begingroup\$ Try a power resistive load at 1A then 2A etc to find the cause \$\endgroup\$ – user51925 Sep 5 '14 at 22:16
  • 1
    \$\begingroup\$ Try adding a circuit. \$\endgroup\$ – Andy aka Sep 5 '14 at 22:35
2
\$\begingroup\$

I have an L298N motor controller module, rated at 5 amps.

In the opening blurb on page 1 of the data sheet it says the L298 can supply a total DC current up to 4 amps.

In the table for absolute maximum ratings it says that the DC current is 2A. You can get 4A when both halves of the bridge work together i.e. they are not used in a H-bridge configuration but a parallel configuration.

I'm using a current sensor per motor to learn when the motors have reached a high current load (~2.26 Amps) then stop them once they reach that threshold.

This will likely lead to early failue of the L298 - respect the data sheet. For \$t_{on}\$ of 10 msecs you can go as high as 2.5 amps - are you adhering to this?

The thermal data for the device is 35degC per watt - are you using a heatsink and what power are you likely dissipating. These are very inefficient devices and warm up very easily because their output transistors do not saturate to anything like a conventional BJT or MOSFET. I'd urge you to read the data sheet on this device and recheck your calculations.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.