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DRV8301 board bringup issues

Saturn Z
Prodigy 80 points

Other Parts Discussed in Thread: DRV8301, TMS320F28027F

Hello TI Folks,

We are developing a DRV8301 based drive for one of customer who is a manufacturer of BLDC motors. We have already bought the BOOSTXL and DRV8301-69M_kit for evaluation purpose. It was amazing to get the motor spinning in a matter of minutes.

Further, we have designed a custom hardware on the lines of BOOSTXL to handle more power (60V, 20A). We're facing issues with bringing up the board with the FAULT pin asserting whenever we ENABLE the DRV8301.

Our setup consists of Custom board connected to C2000 Launchpad (with TMS320F28027F device). Hardware is powered through a lab power supply, set to 20V in current limiting mode. The motor is not connected for now, and we're trying to run the Lab 2c.

After powering up the drive and enabling the EN_GATE pin, the fault LED lights up. Foll. points are worth noting.

a. DVDD = 3.3V, AVDD = 6.94V, VDD_SPI=3.3V, REF=3.3V PVDD1 and PVDD2 = 20V

b. Buck gives out 7V as expected, this is fed to an LDO which outputs a regulated 3.3V

c. The problem area seems to be GVDD = 1.5V. Also, since OCTW is not asserted, the fault seems to be coming from GVDD_UV.

d. There is also a potential of 5.4mV between VDC_GND and AGND.

e. The external current sense circuitry seems to be working, since IC_FB=1.59V whereas, the internal current sense outputs SO1 and SO2 are showing 50mV even thought the REF pin voltage is 3.3V

Since the device gives a FAULT on ENABLE, I am ruling out the DRV8301 being damaged. The SPI status register data read after the FAULT occurs is showing garbage values viz. Device ID = 0x1F.

Attached are schematic and gerber files. Appreciate any pointers to debug this further.

Thanks for your patience.

cheers,

Saturn.

4174.DRV8301_boosterv1.1.pdf

3806.gerbers.zip

  • 0
    TI__Mastermind 21320 points

    Hi Saturn,

    Some things to check...

    • Can you verify that the PowerPAD has been properly soldered? The device makes an electrical connection to GND through the PowerPAD.
    • Is there a partial short on the GVDD pin?
    • It is very strange to be reading garbage on the SPI bus even with a GVDD_UV. What do you read from the other registers?
  • 0 in reply to Nicholas Oborny
    Prodigy 80 points

    Hello Nick,

    Thanks for your quick response.

    Regarding the PowerPAD connection, how can I make sure that it is well connected to ground ? is there any indication for that ?

    I don't have access to a reflow oven, so I designed the PCB with a large solder pad (unmasked) below the DRV8301 and added a few vias stitched to GND in the bottom layer. I soldered the IC by providing the heat from below. After a few tries, I was able to get the connection soldered. With that, the board has come alive. I see all the voltages (GVDD, AVDD, DVDD and PVDD) as expected. SPI also seems to be working, since I see valid values in Status1/2 and Control 1/2 registers and the DRV doesn't FAULT anymore.

    Next hurdle seems to be motor identification. I tried running Lab 2c with a known good motor, however, the motor vibrates (like an earthquake) and draws a very high current (I believe I have set the right current limits and other values for identification in user.h). I suspect mosfets are not switching properly, I will check the gate, Vds signals and let you know how it goes.

    thanks,

    Saturn.

  • 0 in reply to Saturn Z
    TI__Mastermind 21320 points

    Unfortunately there is no good way to check without x-ray or physically slicing the leads off and seeing if the device remains attached (you could also solder the powerPad first and ensure it has a good connection and then solder the leads).

    You next question I will leave for the InstaSPIN guys. Sounds like it is an ID problem, maybe not the driver. Is this a low inductance, high speed motor? I know there are some tricks to improve the ID process for these types of motors (can see the stickys in this forum). To check the MOSFETs you can manually switch the H-bridges by applying your own signal to the DRV8301 INPUTS. This is a pretty easy check to ensure the MOSFETS are switching correctly.

  • 0 in reply to Nicholas Oborny
    Prodigy 80 points

    My h/w is behaving a bit inconsistent, I think that is probably due to a bad connection from PowerPad to GND.

    Anyways, Thanks for the detailed information and great support provided so far.