TUSB2036_16 Datasheet, PDF (15/27 Pages) Texas Instruments – 2- or 3-Port Hub for the Universal Serial Bus

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9 Application and Implementation
TUSB2036
SLLS372H – MARCH 2000 – REVISED JANUARY 2016
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
A major advantage of USB is the ability to connect 127 functions configured in up to 6 logical layers (tiers) to a
single personal computer.
Another advantage of USB is that all peripherals are connected using a standardized four-wire cable that
provides both communication and power distribution. The power configurations are bus-powered and self-
powered modes. The maximum current that may be drawn from the USB 5-V line during power up is 100 mA.
For the bus-powered mode, a hub can draw a maximum of 500 mA from the 5-V line of the USB cable. A bus-
powered hub must always be connected downstream to a self-powered hub unless it is the only hub connected
to the PC and there are no high-powered functions connected downstream. In the self-powered mode, the hub is
connected to an external power supply and can supply up to 500 mA to each downstream port. High-powered
functions may draw a maximum of 500 mA from each downstream port and may only be connected downstream
to self-powered hubs. Per the USB specification, in the bus-powered mode, each downstream port can provide a
maximum of 100 mA of current, and in the self-powered mode, each downstream port can provide a maximum of
500 mA of current.
Both bus-powered and self-powered hubs require overcurrent protection for all downstream ports. The two types
of protection are individual-port management (individual-port basis) or ganged-port management (multiple-port
basis). Individual-port management requires power-management devices for each individual downstream port,
but adds robustness to the USB system because, in the event of an overcurrent condition, the USB host only
powers down the port that has the condition. The ganged configuration uses fewer power management devices
and thus has lower system costs, but in the event of an overcurrent condition on any of the downstream ports, all
the ganged ports are disabled by the USB host.
Using a combination of the BUSPWR and EEDATA/GANGED inputs, the TUSB2036 supports four modes of
power management: bus-powered hub with either individual-port power management or ganged-port power
management, and the self-powered hub with either individual-port power management or ganged-port power
management. Texas Instruments supplies the complete hub solution because we offer this TUSB2036 along with
the power-management devices needed to implement a fully USB compliant system.
Note, even though no resistors are shown in the following applications, pullup, pulldown, and series resistors
must be used to properly implement this device.
Copyright © 2000–2016, Texas Instruments Incorporated
Product Folder Links: TUSB2036
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