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Problems with DRV8811

Alexander Vasiljev
Expert 1015 points
Other Parts Discussed in Thread: DRV8811

We use the 8811 motor drivers. It can run for hours, but sometimes it stops. When it stops the home signal is changing according to the step signal, but the motor doesn't move. And only reseting the driver helps.

How can we distinguish among OCP, TSD, UVLO?

The full current is about 1,4 A. The motor is 2.3 V.

 

 

  • 0
    Prodigy 40 points

    Dear all,

     We also  done a final production board based on specification given in data sheet. Now we can not run motor more than 1.5Amp rating.Our major application set  for 2.5Amp with min.35V supply.We face lots of problem in developing high rating stepper drive.

     My best suggestion to TI is to develop a stepper motor controller with following feature which will definately work in stepper motion field.

    1: Step /Dir/micro step selection etc. direct input

    2: Current set 3/4 digit input which act as a DAC and will give fix reference to internal comparator.     

    3: No internal mosfet H bridge but provide 12V mosfet control signal for both h -bridge for all 8 independent mosfet gate.

    4: Two different current  sense point.

    5: All decay mode featured by digital input pins.

    6: Only stepper control mechanism require with external mosfet h - bridge.

    This kind of chip has high demand in industrial robotic application.

    Ashwin Kaklotar

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  • 0
    TI__Expert 7455 points

    Hi Alexander,

    Sorry to hear about your problem with the DRV8811. Could you please contact me at jquinones@ti.com to get some more information regarding this issue? Thanks!

    Best regards,

    JIQ

  • 0 in reply to ashwin3794
    TI__Expert 7455 points

    Hi Ashwin,

    Thanks for your input on how to improve our line of stepper drivers! But let me answer your 2.5A answer first.

    To reach 2.5A on the DRV8811 is quite tough. This is the absolute maximum condition and the ultimate thermal impedance must be obtained. For example, at 2.5A, the power dissipation is anywhere in between 7.5W to 9.375W. Since Thermal Shutdown occurs at a minimum of 150C, with an ambient of 25C, you only have 125C to spend in device heating. With the power dissipation we just computed, we know we need a thermal impedance in between 13.33 C/W to 16.66 C/W.

    A four layer board alone will hardly ever get to these thermal impedances. According to the datasheet, with a very well designed high temperature 4 layer board, all you will get is about 28 C/W, which is about twice the thermal impedance you need.

    The only way in which I have personally been able to successfully reach the continuous 2.5A mark is by adding a heat sink and a fan. I have heard of people adding heat sinks to the bottom side of the board and the device running pretty cool even at close to 2.5A currents. The reason why this works is because the 4 layer board and the HTSSOP package will give you a maximum power dissipation of about 4W. However, we know we are dealing with more like 9W. Adding a massive enough heat sink to the system will get you to these kinds of power dissipation.

    Now, going back to your very nice suggestions on the ultimate stepper driver device. When you say a device of this nature is on high demand, can you comment on what kind of demand we are talking about here? We are always looking to design the ultimate stepper driver and we would like to understand how many people could benefit from this configuration. Thanks for your input!

    Best regards,

    Jose I Quinones