7.3.1.4.4 Propagation Delay

The propagation delay time (t_pd) is measured as the time between an PWM logic edge detected to the GHX / GLX transition as shown in Figure 13. This time comprises three parts consisting of the digital input deglitcher delay, the digital propagation delay, and the delay through the analog gate drivers.

The input deglitcher prevents high-frequency noise on the input pins from affecting the output state of the gate drivers. To support multiple control modes and dead time insertion, a small digital delay is added as the input command propagates through the device. Lastly, the analog gate drivers have a small delay that contributes to the overall propagation delay of the device.

In order for the output to change state during normal operation, one MOSFET must first be turned off. The MOSFET gate is ramped down according to the IDRIVE setting, and the observed propagation delay ends when the MOSFET gate falls below the threshold voltage.