Using the VNHD7012AY development board to run a brushed 12V motor, I have trouble at initial startup trouble that appears to be a problem with the fault circuitry.

[PCond.1]

Picture #2: (Current waveform) Operation with resistance added to OUT line

Picture #1: (current waveform) Picture when motor does not start Regardless of what values I install for gate resistors (0, 475, 1100 ohm), Vref resistors (8-40K) adding ext filtering (various places), the motor will not start up. If I add a small amount of resistance (0.1-0.4 ohm) into the OUTA or OUTB lines, the motor will start and turn CW or CCW as requested. I feel that if I could filter at the initial startup, somewhere, the operation would be normal. No PWM is required, but might be tried if it would help this startup issue. For the digital signals into the board, I have them statically tied to 3.3V or GND as required to get CW or CCW operation. I haven't changed any of them (from a 0->1) to initiate motor movement. I apply the 12V power to the board, then turn on a second 3.3V PS that applies power for the logic signal as a group. The others are tied low to GND. All PSs have their return lines tied together and tied to chassis for this test.

Thank you,

Pete Condon

[PCond.1]

I purchased a new eval board, the VNHD7008AY instead of the '7012. Unmodified, this '7008 eval board had the same issues. I added a large (4700uF) electrolytic at the very input where the BATT signal enters the eval board and the unit overcame the startup issue. I had a secondary issue where the Vref resistors had to be increased (8K-> 14K TBD) due to excessive startup current tripping the internal current limit occasionally. I used another vendor's data sheet to get some helpful trouble shooting ideas.