BOOSTXL-DRV8301: Not getting proper Gate pulses for MOSFETs

Hi Abdul,

Thanks for posting to the MD forum!

Can you share your schematics to make sure components are correct? Also can you share your commutation sequence and whether you're using 6x or 3x PWM mode? When sending your PWM control signals to the IC, are you ensuring that you're driving the opposite FET in the phase with the inverse of the PWM polarity to charge the bootstrap capacitors? 

For instance, if I'm commutating from A to B, I'll ensure that:

PWM_AH = PWM

PWM_AL = !PWM

PWM_BH = L

PWM_BL = H

Hi Aaron Barrera,

I'm following the same schematic of 'LAUNCHXL-F28069M' and 'BOOSTXL-DRV8301 Rev.B'. I've combined both into one board and running 'proj_lab13b'. It works fine with original launchpad+booster card setup and not in my board. All these signals are observed without connecting the motor.

This is my schematic;

5773.Schematics.pdf

and these are the components lists.

LAUNCHXL-F28069M Hardware Userguide-pages-19-21.pdf

BOOSTXL-DRV8301_BOM.pdf

Numbering is same as in the component lists. For example R1 in launchpad component is denoted as R1 in my schematic also. But in the case of booster, R1 is denoted as R1.B in my schematic.

Thank you

Hi Abdul,

I will be looking into this with my team this week and getting you a response by the end of the week. 

Hi Abdul,

Your original scope shots of the GLx signals look fine.

When measuring GHx, are you measuring differentially from GHx to SHx? If you are measuring GHx to GND, it will capture strange behavior as the gate drive signals are with respect to the source of the MOSFETs.

Hi Aaron,

     All the signals are measured to GND. ie. GHx and GLx to GND. While running the same program in original launchpad+booster card setup and without connecting motor, I get signals as below;

GH_A

GL_A

GH_B

GL_B

GH_C

GL_C

Thank you

HI Abdul, 

Your measurements seem fine, but can you confirm by measuring your GHx signals with respect to SHx? You should be able to see them cycle on and off at around 10V rather than VM + 10V.