When current is going into the phase, propagation delay and driver dead time is determined by whether INLx is rising or falling.

In Figure 2-7, when INLx goes low (green), current is momentarily pulled through the body diode (purple) of the HS FET to continue sinking current into OUTx (red). After a short body diode conduction period, the HS FET begins to conduct (blue).

Figure 2-7 Current Switching With INHx Rising, INLx Falling, and Current Into OUTx

Note how the current direction is the same internally between the body diode of the HS FET and the conduction path of the HS FET. The device can turn on the HS FET instead of allowing the body diode to fully conduct because the current direction is the same. This results in a shortened propagation delay and dead time.

The example waveform in Figure 2-8 shows INHx rising and INLx falling and current is going into the phase (positive current in green) for the DRV8316 with a slew rate of 200 V/µs and sinusoidal commutation. The dead time and propagation delay minimum values in the DRV8316 data sheet specifications are not specified because of this condition, where propagation and dead times can be much shorter than specified due to the internal VGS handshaking feature of the device to avoid any shoot-through conditions.

Figure 2-8 Waveforms of Dead Time and Propagation Delay When INHx is Rising, INLx is Falling, and Current Flows Into OUTx