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2022 Microchip Technology Inc. and its subsidiaries

DS00002514B-page 25

USB4715

8.0

FUNCTIONAL DESCRIPTIONS

This section details various USB4715 functions, including:

• Downstream Battery Charging

• FlexConnect

• USB to GPIO Bridging

• USB to SMBus/I2C Bridging

• USB to SPI Bridging

• USB to UART Bridging

• Link Power Management (LPM)

• Port Power Control

• Resets

8.1

Downstream Battery Charging

The device can be configured by an OEM to have any of the downstream ports support battery charging. The hub’s role

in battery charging is to provide acknowledgment to a device’s query as to whether the hub system supports USB battery

charging. The hub silicon does not provide any current or power FETs or any additional circuitry to actually charge the

device. Those components must be provided externally by the OEM.

If the OEM provides an external supply capable of supplying current per the battery charging specification, the hub can

be configured to indicate the presence of such a supply from the device. This indication, via a handshake on the D+ and

D- at the start of the connection with the device, is on a per port basis. For example, the OEM can configure two ports

to support battery charging through high current power FETs and leave the other two ports as standard USB ports.

For detailed information on utilizing the USB4715 battery charging feature, refer to the application note “USB Battery

Charging with Microchip USB4715 and USB49xx Hubs”, which can be found on the Microchip USB4715 product page

at www.microchip.com/USB4715.

8.2

FlexConnect

The USB4715 allows any of the 4 FlexConnect capable USB ports to assume the role of USB host at any time during

hub operation. This host role exchange feature is called FlexConnect.

This functionality can be used in two primary ways:

1.

Host Swapping: This functionality can be achieved through a hub wherein a host and device can agree to swap

the host/device relationship; The host becomes a device, and the device becomes a host.

2.

Host Sharing: A USB ecosystem can be shared between multiple hosts. Note that only 1 host may access to

the USB tree at a time.

FlexConnect can be enabled through any of the following three methods:

•

SMBus Control: An embedded SMBus master can control the state of the FlexConnect feature through basic

write/read operations.

•

USB Command: FlexConnect can be initiated via a special USB command directed to the hub’s internal Hub

FIGURE 8-1:

BATTERY CHARGING EXTERNAL POWER SUPPLY

SOC

VBUS[n]

PRT_CTL[n]

INT

SCL

SDA

Microchip

Hub

DC Power