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DRV8301: DRV8301

Bhaktprakash Patel
Prodigy 70 points
Part Number: DRV8301
Other Parts Discussed in Thread: , TPS54160, TM4C123AH6PM

We have been in volume production for over 2 years, using the DRV8301.
On a recent batch of 12 units, 3 units are behaving strangely.
Upon close inspection, the pre-driver output for 5V generation, out from pin 50 and pin 51, has a ripple of +-0.8V about the 5V line at startup, then stabilizes. 
Good units do not have this issue. We have not changed the BOM or the PCB !!!
I have read the spec, there is no mention on how to calculate the RC combination on pin COMP, and there is also no information on how to calculate the resistor divider for pin VSENSE.

I looked at your design "BOOSTXL-DRV8301_SCH" and you use the same COMP RC combination as shown in your data sheet.
Note, "BOOSTXL-DRV8301_SCH" produces 3.3V from the DRV8301, on our design we created 5V. I do not know how the COMP pin would change because of this.
The previous designer used a different RC combination {39pF || (28k + 6800pf)} your designs have {120pF || (16.2k + 6800pf)}

Can you tell me what the VSENSE voltage is meant to be when operating? Equations would help.

We have been in volume production for over 2 years, using the DRV8301.
On a recent batch of 12 units, 3 units are behaving strangely.
Upon close inspection, the pre-driver output for 5V generation, out from pin 50 and pin 51, has a ripple of +-0.8V about the 5V line.
Good units do not have this issue. We have not changed the BOM or the PCB !!!
I have read the spec, there is no mention on how to calculate the RC combination on pin COMP, and there is also no information on how to calculate the resistor divider for pin VSENSE.

I looked at your design "BOOSTXL-DRV8301_SCH" and you use the same COMP RC combination as shown in your data sheet.
Note, "BOOSTXL-DRV8301_SCH" produces 3.3V from the DRV8301 and our design we created 5V. I do not know how the COMP pin would change because of this.
The previous designer used a different RC combination {39pF || (28k + 6800pf)} your designs have {120pF || (16.2k + 6800pf)}

Can you tell me what the VSENSE voltage is meant to be when operating? Equations would help.

Please take a look the attached schematics.

  • 0
    TI__Mastermind 21805 points

    Hello Bhaktprakash,

    Thanks for your post!

    Can you provide me a picture of the topside marking on these units so we can check out the lot trace code?

    The DC/DC regulator integrated into the DRV8301 is the the TPS54160, and so you can cite that device datasheet as well as WEBENCH for other design resources.

    The schematic did not come through - you may have to click the "Insert/Edit Media" button in the taskbar to attach your schematic image.

    Thanks,

    Matt

  • 0 in reply to Matt Hein
    Prodigy 70 points

    Hello

    1. I will send the topside marking of the part later on today. We have a two board set solution, I do not want to open up the boards yet, I am still probing around. Will get it to you for sure.

    2.  I will read up on the TPS54160.

    3. See attached file.

    4. I also added an image of what the 5V output looks like after the 33uH (L1 pin 2). All these scope images are at various time as we turn on the motor. This 5V goes to a LDO, which also produces an ugly 3.3V supply to the TI  TM4C123AH6PM (see we kept all our parts in the TI family !!!).    

    Thanks

    Buck Patel 

    TI_Driver_chip.pdfTI_Driver_chip.pdf 

  • 0 in reply to Bhaktprakash Patel
    TI__Mastermind 21805 points

    Hi Buck,

    I'm surprised the LDO isn't filtering out more of this noise on the buck output.

    I plugged a few things into  WEBENCH to see what values it would spit out (not knowing your operating voltage range and intended buck output current).

    • The COMP values that result are significantly different than your schematic values
    • You may want to check your VSENSE routing on the board to see if it is picking up any noise

    Thanks,

    Matt