• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 29 subscribers
  • Views 873 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV8308

Mikael Sundberg
Intellectual 740 points
Other Parts Discussed in Thread: DRV8308, DRV8308EVM, DRV8303EVM

Hi,

We have spent two days with an issue regarding this motor driver. We have constructed our own 2 layers pcbs and interface to the drv8308 using a mcu. Everything works perfectly. We can write to the registers and read them back and so on. No issues at all. The problem occurs when we raise the enable pin or use the register with the enpol set high. The drv8308 draws almost an amp of power and gets very hot, until enable is set low again. During this time the drv8308 continues to receive commands without any issues. We have this issue no matter if the motor is connected or not. We have two pcbs and it is the same on both of them. We have followed the schematics from the drv8308evm almost completely, allthough we use higher power mosfets. Same hall-sensors same components in the circuit. We have checked all connections several times and they show no problems what so ever. This seems weird. Anyone have any idea of what can be going on? Is this maybe a faulty batch of drv8308? Where is the power going?

Best regards,

Mikael Sundberg

  • 0
    TI__Mastermind 26065 points
    Hi Mikael,

    So, when you say everything is fine, you haven't spin the motor yet, right? Now the problem is the driver outputs current much higher than expected when enabled.

    Could you share the schematic of the driver and our experts will get back to you later.

    Best regards,
  • 0
    TI__Mastermind 20985 points

    Mikael, that is strange.  You can also look at the schematic of this TI Design as a reference: www.ti.com/.../tida-00197

    I'm most suspicious about something being wrong with one of the power pins:  CP1, CP2, VCP, VM, VINT, or VREG.  Check for shorts with each other and shorts to GND.  Make sure the capacitors on these pins are actually capacitors (not zero ohm resistors!).

    Also, of course keep in mind that the DRV8308 on your board might be bad now that you put an amp through it.  So if you identify and fix a PCB problem, you might need to solder a new DRV8308 unit.  With no motor connected, the DRV8308 should only draw about 15mA.

    Best regards,
    RE

  • 0 in reply to Wilson Zuo
    Intellectual 740 points
    Correct, not any reaction out on the motor yet. Schematic is almost identical to that of the drv8303evm. The only small difference is that we use more powerful mosfets.
    I will replace the drivers with new ones on monday. It the last thing to try now.
  • 0 in reply to RE
    Intellectual 740 points
    Replacement chip on its way. It was a indeed a short from VREG to GND on the PCBs. Thank you for that input. Problem solved!