USB3813 datasheet(39/57 Pages) MICROCHIP

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USB 2.0 Hi-Speed 3-Port Hub Controller Optimized for Portable Applications

Datasheet

 2014 Microchip Technology Inc.

DS00001715A-page 39

A downstream port will behave as a CDP, DCP, or SDP depending on the port’s configuration and

mode of operation. The port will not switch between a CDP/DCP or SDP at any time after initial power-

up and configuration. A downstream port can be in one of three modes shown in the table below.

8.1.2.2

Downstream Battery Charging Configuration

Configuration of ports to support battery charging is performed via USB configuration, SMBus

configuration, or OTP. The Battery Charging Enable Register provides per port battery charging

configuration. Starting from bit 1, this register enables battery charging for each down stream port when

asserted. Bit 1 represents port 1 and so on. Each port with battery charging enabled asserts the

corresponding PRTPWR register bit.

8.1.2.3

Downstream Over-Current Management

It is the devices responsibility to manage over-current conditions. Over-Current Sense (OCS) is

handled according to the USB specification. For battery charging ports, PRTPWRA is driven high

(asserted) after hardware initialization. If an OCS event occurs, the PRTPWRA is negated.

If there is an over-current event in DCP mode, the port is turned off for one second and is then re-

enabled. If the OCS event persists, the cycle is repeated for a total or three times. If after three

attempts, the OCS still persists, the cycle is still repeated, but with a retry interval of ten seconds. This

retry persists for indefinitely. The indefinite retry prevents a defective device from permanently disabling

the port.

In CDP or SDP mode, the port power and over-current events are controlled by the USB host. The

OCS event does not have to be registered. When and if the hub is connected to a host, the host will

initialize the hub and enable its port power. If the over current still exists, it will be notified at that point.

Table 8.3 Downstream Port Types

USB ATTACH TYPE

DP/DM PROFILE

DCP

(Dedicated Charging Port)

Apple charging mode or

China Mode (Shorted < 200ohm) or

MCHP custom mode

CDP

(Charging Downstream Port)

VDP reflected to VDM

SDP

(Standard Downstream Port)

USB Host or downstream hub port

15Kohm pull-down on DP and DM

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