XR22404 Datasheet, PDF (8/14 Pages) Exar Corporation – USB 2.0 4-Port Hub

XR22404
Applications Information (Continued)
Battery Charging
The XR22404 will provide downstream charging irrespective of its state, i.e., enumerated, detached, operational, or
suspended as long as it is powered by an external source, i.e., self-powered. In bus powered mode, VBUS power is not
capable of providing sufficient power for the XR22404 to charge downstream devices.
If the XR22404 device is self-powered and LED_CTL/CHRGEN pin is tied to a logic ‘1’ during power up or external reset, the
XR22404 battery charging function will be enabled on all downstream ports. If the device is self-powered and connected to
an upstream USB host, the XR22404 will function as a Charging Downstream Port (CDP). If the device is self-powered but
not connected to a USB host, the XR22404 will function as a Dedicated Charging Port (DCP). Refer to Table 1.
Table 1. Downstream Port Capability
CHRGEN
Logic ‘1’
Logic ‘1’
“X”
Logic ‘0’
VBUS_SENSE
Logic ‘1’
Logic ‘0’
Logic ‘1’
Logic ‘1’
BUS_PWR#
Logic ‘1’
Logic ‘1’
Logic ‘0’
“X”
Capability
CDP - Connected to upstream USB host, downstream ports may be used in
normal hub operation or for charging.
DCP - Not connected to upstream USB host, all downstream ports may be
used for charging.
SDP - Bus power is not capable of providing enough power for battery
charging capability, downstream ports used in normal hub operation.
SDP - Normal hub operation.
USB Hub Drivers
All Operating Systems provide a native USB hub device driver required for the XR22404 device to operate. No other device
drivers are necessary for the XR22404.
Regulated 3.3V Power Output
The XR22404 internal voltage regulator provides 3.3 VDC output power from 5V input, which can be utilized by
other circuitry. Refer to Electrical Characteristics on page 2 for maximum power capability.
REV1A
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