7.4.3 Semi-Auto

No activity takes place on the port until the DETEn bit in the Detect/Class Enable register is set. When DETEn is set, port n automatically performs detection. If a valid PD is detected and CLEn is set, the port initiates a classification cycle. The classification cycle is single-event if a class 0, 1, 2 or 3 PD is recognized. If the first classification event returns a class 4 signature, a second classification event is initiated depending on the setting of the TECLENn field in the Two-Event Classification Register. The cycle of detect, then classification repeats continuously.

Powering on the port requires writing to the pushbutton PWONn bit in the Power Enable Register. The port powers on meeting the IEEE T_P(on) requirement to power on within 400 ms of the end of a valid detection. Depending on the timing of the PWONn command, the controller may initiate a new detect and (if CLEn is set) classification sequence before powering on the port if required to meet the T_P(on) requirement. If the final detect is invalid, or if the final classification returns overcurrent or class mismatch, the port will not power on and the STRTn bit is set in the Start/ILIM Event Register. For Turn-On sequencing see Push-Button Power On Response.

Following a power-off command, disconnect or shutdown due to a Start, ICUT or ILIM fault, the port powers off. Following a shutdown due to a start, ILIM or ICUT fault, the TPS23861 enters into a cool-down period. During the cool-down period any port power on command using Power Enable Command is ignored. The length of the cool-down period is set in the CLDN field of the Cool Down/Gate Drive Register. After the end of the cool-down period the TPS23861 initiates a detect cycle and continues semi-automatic operation.