USB2533 datasheet(34/50 Pages) MICROCHIP

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USB 2.0 Hi-Speed 3-Port Hub Controller

Datasheet

DS00001702A-page 34

 2014 Microchip Technology Inc.

If a custom charger detection algorithm is desired, the SMBus registers can also be used to control

the charger detection block to implement a custom charger detection algorithm. In order to avoid

negative interactions with automatic battery charger detection or normal hub operation, the user should

only attempt Custom battery charger detection during the Hub.Config stage or Hub.Connect stage. No

logic is implemented to disable custom detection at other times - it is up to the user software to observe

this restriction.

There is a possibility that the system is not running the reference clock when battery charger detection

is required (for example if the battery is dead or missing). During the Hub.WaitRefClk stage the battery

charger detection sequence can be configured to be followed regardless of the activity of REFCLK by

relying on the operation of the internal oscillator.

8.1.2

Downstream Battery Charging

The device can be configured by an OEM to have any of the downstream ports to support battery

charging. The Hub's role in battery charging is to provide an acknowledge to a device's query as to if

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 as

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 to the device. This

indication, via the PRTPWR[1:4] output pins, is on a per/port basis. For example, the OEM can

configure two ports to support battery charging through high current power FET's and leave the other

two ports as standard USB ports.

8.1.2.1

Downstream Battery Charging Modes

In the terminology of the USB Battery Charging Specification, if a port is configured to support battery

charging, the downstream port is a considered a CDP (Charging Downstream Port) if connected to a

Apple Charger Low Current Charger (500mA)

DP=2.0V

DM=2.0V

100

Apple Charger High Current Charger (1000mA)

DP=2.0V

DM=2.7V

101

Figure 8.1 Battery Charging External Power Supply

Table 8.1 Chargers Compatible with Upstream Detection (continued)

USB ATTACH TYPE

DP/DM PROFILE

CHARGERTYPE

SOC

VBUS[n]

PRTPWR[n]

INT

SCL

SDA

Microchip

Hub

DC Power

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