TPS2070, TPS2071

FOUR-PORT USB HUB POWER CONTROLLERS

SLVS287A – SEPTEMBER 2000 – REVISED FEBRUARY 2001

24

POST OFFICE BOX 655303

APPLICATION INFORMATION

universal serial bus (USB) applications

The universal serial bus (USB 1.1) interface is a 12-Mb/s, 1.5-Mb/s, or 480 Mb/s (USB 2.0), multiplexed serial

bus designed for low-to-medium bandwidth PC peripherals (e.g., keyboards, printers, scanners, and mice). The

four-wire USB interface is conceived for dynamic attach-detach (hot plug-unplug) of peripherals. Two lines are

provided for differential data, and two lines are provided for 5-V power distribution.

USB data is a 3.3-V-level signal, but power is distributed at 5 V to allow for voltage drops in cases where power

is distributed through more than one hub or across long cables. Each function must provide its own regulated

3.3 V from the 5-V input or its own internal power supply.

The USB specification defines the following five classes of devices, each differentiated by power-consumption

requirements:

Self-powered and bus-powered hubs distribute data and power to downstream functions. The TPS2070 and

TPS2071 can provide power-distribution solutions for hybrid hubs that need switching between BPH and SPH

according to power availability and application requirements.

USB power-distribution requirements

USB can be implemented in several ways, and, regardless of the type of USB device being developed, several

power-distribution features must be implemented.

–

Current-limit downstream ports

–

–

Output 5.25 V to 4.75 at 500 mA

–

Enable/disable power to downstream ports

–

Power up at <100 mA

–

Limit inrush current (<44

Ω and 10 µF)

–

Output 5.25 V to 4.4 at 100 mA

–

Not send power back upstream

–

Limit inrush currents

–

Power up at <100 mA

–

Not send power back upstream (SP functions)

The feature set of the TPS2070 and TPS2071 allows them to meet each of these requirements. The integrated

current-limiting and overcurrent reporting is required by hosts and self-powered hubs. The logic-level enable

and controlled rise times meet the needs of both input and output ports on hubs, as well as the input ports for

bus-powered functions