USB 2.0 Hi-Speed 4-Port Hub Controller
Datasheet
DS00001713A-page 36
2014 Microchip Technology Inc.
USB host, or a DCP (Dedicated Charging Port) if not connected to a USB host. If the port is not
configured to support battery charging, the port is considered an SDP (Standard Downstream Port).
All charging ports have electrical characteristics different from standard non-charging ports.
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 the BC_EN configuration straps,
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, PRTPWR is driven high
(asserted) after hardware initialization. If an OCS event occurs, the PRTPWR is negated. PRTPWR
will be negated for all ports in a ganged configuration. Only the respective PRTPWR will be negated
in the individual configuration.
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 8.2 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
