Hi Mike,
Sorry, I was not clear on my comment. R7, R8, and R9 are reducing the gate voltage of the low side FETs. This is not recommended as it increases the RDSon, lowering the overall efficiency of the system.
More information:
- The PWRGD, FAULT and OCTW are all high, indicating no issues with the buck converter or the motor controller
- PWRGD is a indication the buck is working. FAULT and OCTW are indications that the gate driver has no problems. The buck is independent of the gate driver.
- GVDD, AVDD pins output 0V even when we run a
- No gate voltage (GH_A, GL_A, GH_B, etc...) when we apply a 0V-5V PWM at 50% Duty Cycle through with H1 M_PWM set high
- Are you setting EN_GATE high? If not, the device is in a low power mode.
- If connected to a power supply, do you see additional current draw when EN_GATE is set high?
- CP1/CP2 outputs 0V
- This should be corrected once you find the cause of GVDD/AVDD pins above.
- Our SS_TR is currently floating. Is this okay or does there have to be a cap to GND here?
- It is recommended to connect a cap. Please see second to last paragraph of page 15 for more details.
- BST_BK is an unstable 11V
- This is correct
- RT_CLK is a stable 0.475V (is this good or bad?)
- this is good.
FYI -- The most comprehensive information about the buck converter is available through the TPS54160 datasheet.