USB3503 datasheet(61/82 Pages) SMSC

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USB 2.0 HSIC High-Speed Hub Controller Optimized for Portable Applications

Datasheet

SMSC USB3503A

Revision 1.1 (02-07-13)

DATASHEET

Chapter 8 Battery Charging

In order to detect the charger, the device applies and monitors voltages on the USBUP_DP and

USBUP_DM pins. If a voltage within the specified range is detected, the Charger Detection Register

in the I2C register space shall be updated to reflect the proper status.

8.1

Downstream Port Battery Charging Support

The USB3503 can configure any of the downstream ports to support battery charger handshake.

The Hub’s role in downstream 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 such thing to actually charge the device. Those components would need to be

provided as external components in the final Hub board design.

If the final Hub board design 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 is on a per/port basis. i.e. the board can configure two ports to support battery

charging (thru high current power FET’s) and leave the other port as a standard USB port.

8.1.1

USB Battery Charging

In the terminology of the USB battery charging specification, if the port is configured to support battery

charging, the downstream port is a “Charging Host Port”. All AC/DC characteristics will comply with

only this type. If the port is not configured to support battery charging, the port is a “Standard Host

Port”. AC/DC characteristics comply with the USB 2.0 specification.

A downstream port will only behave as a “Charging Host Port” or a “Standard Host Port”. The port will

not switch between “Charging Host Port” or Standard Host Port” at any time after initial power-up and

configuration.

8.1.2

Special Behavior of PRTPWR Register

The USB Battery charging specification does not address system issues. It only defines a low level

protocol for a device and host (or hub) to communicate a simple question and optional answer.

Device queries if the host to which it is connected supports battery charging.

The host will respond that it does support battery charging or does not respond at all. There is no

negative response. (A lack of response is taken as a negative response)

Figure 8.1 Battery Charging External Power Supply

SOC

VBUS

PRTPWR

USB3503

(Serial Mapped

INT

SCL

SDA

DC Power

USB3503 Datasheet(PDF) 61 Page - SMSC Corporation

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