Problems with L298

Discussion in 'General Electronics Chat' started by alexx_88, May 24, 2010.

  1. alexx_88

    Thread Starter New Member

    May 24, 2010
    17
    0
    Hello!

    I am currently working on a first project, designing and implementing a Cruise Control Adaptive system for a toy car. I am having problems in getting the L298 to work.

    I have measured the following inputs on the L298:
    Pin 4 - Vs - 8.3V
    Pin 9 - Vcc - 4.9V
    Pin 11 - Enable B - 4.9V
    Pin 10 - Input 3 - 0V
    Pin 12 - Input 4 - 4.9 V

    When measuring between pins 13 and 14 (Out 3 and Out 4) it reads 0V. I've connected both sense A and sense B directly to ground.

    I've also changed the L298 once, thinking that I've installed a faulty chip. I am running out of ideas :(.

    Alex
     
    Last edited: May 24, 2010
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    Can you post the board and schematic as .png format?
    Perhaps a screenshot will do.
    I can not read the attachments as they are.

    Bertus
     
  3. alexx_88

    Thread Starter New Member

    May 24, 2010
    17
    0
    I have modified my first post.

    Alex
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Hi Alex,

    Did you install the L298 from the bottom of the board? I ask this because you used the mirror image function on the L298. If you inserted it from the top of the board, all of the pin connections will be reversed.

    [eta]
    Don't forget to look at the saturation voltage drop.

    At 1A, you'll lose about 3.2v, at 2A you'll lose around 4.9v in the bridge itself.
     
    Last edited: May 25, 2010
  5. alexx_88

    Thread Starter New Member

    May 24, 2010
    17
    0
    I think you are a GENIUS! :) I installed the two L298s from the top of the board, forgetting (not noticing) that I mirrored the component when I designed the PCB.

    Unfortunately, I have quite a workload these days so the closest day I could think of for testing the L298 is Thursday night. I don't see any reason for it not to work though.

    Thank you again!
    Alex
     
  6. alexx_88

    Thread Starter New Member

    May 24, 2010
    17
    0
    I have put the L298 from the bottom of the board and it works perfectly. After I'll complete my project I will post a few more details in the dedicated section.

    Thank you for your help!
    Alex
     
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