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DRV8256: Output not activating.

SREEHARI P
Prodigy 20 points
Part Number: DRV8256
Other Parts Discussed in Thread: DRV8235,

Tool/software:

Hi team,

I facing different issues with TI motor driver chips. First i selected DRV8235 to drive A linear actuator 24V 3A. While controlling actuator movement the chip burned. Finally we found that  chip is not suitable for our application(Even though the power rating of actuator is below the maximum caapcity of DRV8235). 

So we selected DRV8256. No i facing an issue

All control pins and power pins are at correct voltage levels, but the output not activated. The drivers were working. I have 5 actuators in my pcb..

While I was working, one or two drivers had to work. Then, even though I tried to drive, drivers who weren't even there had to work.

current issue: all drive pins and voltage pins are ok, but ouput not activating.

  • 0
    TI__Genius 10311 points

    Hi Sreehari,

    Thanks for your question.

    Can you confirm if which hardware you used for testing this, Are you using the EVM. Also can you let us know how the actuator is connected across the output.

    Thanks,

    ibinu

  • 0 in reply to Ibinu Alaudeen Nadeera
    Prodigy 20 points

    Hi Ibinu,
    I am using DRV8256ERGER
    I connected the actuator across OUT1 and OUT2 by connecting 1nf capacitors, one for OUT1 and another for OUT2.
    Also one 1.6pf TVS diode parallel to OUT1 and OUT2. 
    Image is attached

  • 0 in reply to SREEHARI P
    TI__Expert 3360 points

    Hi Sreehari, 

    Thank you for reaching out to us. Would you please share the following information to better assist you with this issue. 

    1- Would you please share the whole DRV schematic to be reviewed. 

    2- Would you please share a capture of EN, PH,  nSLEEP , nFAULT and outputs waveforms,  

    Best regards, 

    Mojtaba

  • 0 in reply to Mojtaba Afshar
    Prodigy 20 points

    Hi, This is our motor driver schematics
    Th actuator specifications are:
    24V DC 55 watt
    It has limit switches inside actuator at both ends, to break the circuit

  • 0 in reply to SREEHARI P
    TI__Expert 3360 points

    Hi Sreehari, 

    Thank you for sharing the information. The schematic looks good. However, it should be considered When VREF is tied to DVDD or an external 5 V, the device can deliver maximum 6.4 A peak current. However, the thermal performance of the device must be carefully considered - heat sinks might be required to drive more than 5 A peak current.

     Would you please share a capture of EN, PH,  nSLEEP , nFAULT, Vref and outputs waveforms. 

    Best regards, 

    Mojtaba.