Datasheet

GND

0.1 µF

2, 3

6, 7, 8

0.1 µF 120 µF

GND

OUT

TPS2041B

Power Supply

D+

D−

BUS

Downstream

USB Ports

USB

Control

3.3 V 5 V

TPS2041B, TPS2042B

TPS2043B, TPS2044B, TPS2051B

TPS2052B, TPS2053B, TPS2054B

SLVS514L –JUNE 2010–REVISED JUNE 2011

www.ti.com

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

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

TPS204xB/TPS205xB can provide-power distribution solutions to many of these classes of devices.

HOST/SELF-POWERED AND BUS-POWERED HUBS

Hosts and self-powered hubs have a local power supply that powers the embedded functions and the

downstream ports (see Figure 33 and Figure 34). 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.

Figure 33. Typical One-Port USB Host / Self-Powered Hub