Part Number:DRV8301
Tool/software: Code Composer Studio
Hi,
I have built a dual motor board based on the F28069M Launchpad and two DRV8301s. I am using the buck converter of the first DRV8301 and have disabled the buck converter on the second DRV8301 (Other than EN_BUCK which is tied to GND all the other buck converter related pins on this DRV8301 are floating - RTCLK, COMP, VSENSE, PWRGD,SS_TR,PVDD2, BST_BK, PH). Also note that the circuit layout for the problematic DRV8301 is very similar to the first.
The first DRV8301 is working fine and I am able to spin a motor. For the second DRV8301, after starting debugging in CCS and activating EN_GATE the nFAULT pin is asserted and looking at it with an oscilloscope the fault seems to pulse off for a fraction of a second every millisecond. Looking at the SPI status registers 1 and 2 all the status bits are 1(This could be garbage if there is an SPI issue). I had a look at the voltage of GVDD and it is around 11.1V (The same as the other working DRV8301). When starting PWM output however this GVDD drops to around 9V+- 0.2V, whereas the GVDD on the first DRV8301 is stable.
Looking at the GH and GL outputs shows a weak but tiny frequency output on all 3 phases on the second DRV8301.
Please note that for these tests I did not have a motor connected to either output. I also confirmed with my board manufacturer that the powerPAD GNDs are also soldered.
Could you please offer some direction as to other things that I can check in order to determine the cause of this issue?
Thanks in advance!