Some users do not execute AC diagnostics only during power-on initialization, but rather run AC diagnostics when the system detects no sound or encounters other anomalies during operation. At this time, the initial state of all channels is not Hi-Z, but Play mode. Since the mode switching of the TAS6424E-Q1 requires a certain amount of time, to ensure the normal operation of AC diagnostics, it is recommended to wait for 10ms after setting the channels to Hi-Z, and confirm that the mode has switched to Hi-Z via status register readback before starting the AC diagnostic flow. For the device, the precondition for the AC diagnostic flow is that all channels must be in the Hi-Z state.

Without state verification, the device might enter the AC diagnostic flow while in Play mode or DC diagnostic mode, causing the device to enter an error state and the AC diagnostic flow to fail. In some scenarios, the system may even erroneously identify the channel status as DC diagnostic mode, as shown in Figure 3-5.