Datasheet

TPS2060, TPS2064

TPS2068, TPS2069

www.ti.com

SLVS553K – MARCH 2005– REVISED MAY 2011

UNIVERSAL SERIAL BUS (USB) APPLICATIONS

The universal serial bus (USB) interface is a 12-Mb/s, or 1.5-Mb/s, 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 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:

• Hosts/self-powered hubs (SPH)

• Bus-powered hubs (BPH)

• Low-power, bus-powered functions

• High-power, bus-powered functions

• Self-powered functions

SPHs and BPHs distribute data and power to downstream functions. The TPS206x has higher current capability

than required by one USB port; so, it can be used on the host side and supplies power to multiple downstream

ports or functions.

HOST/SELF-POWERED AND BUS-POWERED HUBS

Hosts and SPHs have a local power supply that powers the embedded functions and the downstream ports (see

Figure 22). This power supply must provide from 5.25 V to 4.75 V to the board side of the downstream

connection under full-load and no-load conditions. Hosts and SPHs are required to have current-limit protection

and must report overcurrent conditions to the USB controller. Typical SPHs are desktop PCs, monitors, printers,

and stand-alone hubs.