Figure 7-1 shows the circuit used to measure most switching parameters. The top device in this circuit is used to re-circulate the inductor current and functions in third-quadrant mode only. The bottom device is the active device that turns on to increase the inductor current to the desired test current. The bottom device is then turned off and on to create switching waveforms at a specific inductor current. Both the drain current (at the source) and the drain-source voltage is measured. Figure 7-2 shows the specific timing measurement. TI recommends to use the half-bridge as a double pulse tester. Excessive third-quadrant operation can overheat the top device.

Figure 7-1 Circuit Used to Determine Switching Parameters

Figure 7-2 Measurement to Determine Propagation Delays and Slew Rates