USB5806 datasheet(39/60 Pages) MICROCHIP

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DS00002236D-page 39

USB5806

USB Billboard is supported by the USB5806 in conjunction with an external USB Power Delivery capable controller that

supports the USB PD stack and alternate mode negotiation.

When a USB Type-C enabled product supports alternate modes for enhanced capability beyond what is available

through USB connectivity alone, that product must support a USB Billboard endpoint so that a user will be notified by

an operating system when the enhanced capability is not enabled due to an alternate mode mismatch.

A good example of alternate mode functionality is support for a DisplayPort monitor that many docking stations provide.

In this case, the docking station offers DisplayPort (DP) capability over the USB-C connector as an alternate mode.The

DP monitor will only function correctly when a successful alternate mode negotiation occurs between the docking station

and the notebook PC (this is the USB-C to USB-C connection). In order for the alternate mode negotiation to succeed,

the Notebook and the Docking Station must both support DP over USB-C, and have the DP messaging capability

enabled to support alternate mode negotiation. If the alternate mode negotiation is successful, then the notebook and

the Docking Station both change their multiplexers to enable DP signaling over USB Type-C. In this case, no USB Bill-

board messages need to be displayed.

If the above example instead uses a notebook that doesn’t support DP over USB-C, then the alternate mode negotiation

will fail. The docking station will not have a way to enable the DP monitor capability, reducing functionality for the cus-

tomer. For this is the reason, USB Billboard capability is mandated. In this case, a USB Billboard device class endpoint

must appear on a hub port within the Docking Station, and it must provide text and or a web site link which will provide

information to the user regarding the corrective steps required to use the feature.

In the case of the USB5806, all of the above mentioned negotiation capability will occur outside of the USB5806 via an

external USB Power Delivery capable device that contains a full USB PD stack and can communicate via USB PD mes-

saging. In an alternate mode failure case, the USB5806 will provide that message by allowing the USB host to enumer-

ate an internal USB Billboard Device Class just after the failure in response to a signal from the external USB PD

controller. The Billboard Device descriptors will contain the failure message to the USB Host. The message itself will be

prerecorded in the device’s OTP memory.

8.9.1

BILLBOARD ENABLE IN OTP AND GPIOx PIN USE

Any of the GPIOx pins may be selected to use as the BILLBOARD_EN input. By default, GPIO68 is selected when the

Billboard feature is enabled.

The BILLBOARD_EN input signal is active low. When the pin is driven low by a Power Delivery controller to indicate

an alternate mode negotiation failure, the Billboard functionality will activate.

TABLE 8-8:

USB 3.X PORT SPLIT TOGGLE TIME REGISTER

USB3_PORT_SPLIT_TOGGLE_TIME

(0X4176 - RESET=0X05)

USB 3.X PORT SPLIT TOGGLE TIME REGISTER

BIT

NAME

R/W

DESCRIPTION

[7:0]

PORT_SPLIT_TOGGLE_

TIME[7:0]

R/W

The PORT_SPLIT_TOGGLE_TIME is used to control the length of

time port power is toggled off. This is specific to the

“PRTPWRx_USB3_SPLIT” pin, and is only used in conjunction with

0X4171. The timer is always reset whenever the toggle completes.

The minimum toggle time is 350ms and is represented by

00000000b.

Each incremental value will add 10ms to the 350ms minimum value.

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