TPS2047, TPS2057

TRIPLE CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES

SLVS194 – APRIL 1999

20

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

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.

D Bus-Powered Hubs must:

–

Enable/disable power to downstream ports

–

Power up at <100 mA

–

Limit inrush current (<44

Ω and 10 µF)

D Functions must:

–

Limit inrush currents

–

Power up at <100 mA

The feature set of the TPS2047 and TPS2057 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 need of both input and output ports on bus-power hubs, as well as the input

ports for bus-power functions (see Figure 32).