Phil,
1) The DTC resistor (pin 3) is the value that I increased. As it was increased, the flow through spike moved with the increased time.
2) I tried pull down resistors down to 250 ohms, with no effect.
3) I increased the gate drive up to 20 ohms, with no effect. I'll try at 50, but because of the high PWM frequency, this is not likely to be an acceptable solution if it works.
We use a circuit that is nearly identical (same driver, same FETs) to the one used in your 1-kW/36-V Power Stage for Brushless Motor in Battery Powered Garden and Power Tools (TIDU708) app note. Figures 26 & 27 show this flow through spike. I want to know the fundamental reason (what electrically is happening to the driver) for this behavior.
Increasing the gate drive peak current from 0.25A to either 0.7A or 1.7A causes the flow-through current in increase.