The AFE20408 power up sequence is designed to protect the PA. During start-up, the outputs are connected to ground. This ensures that the PA stays off as the AFE20408 powers up. Additionally, the PAON output stays low until the user enables the PAON output allowing the option to keep the PAVDD from connecting to the PA until the system is fully configured. Figure 4-1 shows the output glitch during start-up. The glitch for the outputs are nominally 15mV, ensuring the PA does not turn on during start-up.

Figure 4-1 AFE20408 Positive Startup

In the case of an unplanned voltage shut off, such as one of the input voltages collapsing, the device sets all outputs to ground and disables the PAON to protect the device and the PA.