Datasheet

TPS2044, TPS2054
QUAD POWER-DISTRIBUTION SWITCHES
SLVS174B – JULY 1998 – REVISED FEBRUARY 1999
21
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.
Hosts/self-powered hubs must:
– Current-limit downstream ports
– Report overcurrent conditions on USB V
BUS
Bus-powered hubs must:
– Enable/disable power to downstream ports
– Power up at <100 mA
– Limit inrush current (<44 Ω and 10 µF)
Functions must:
– Limit inrush currents
– Power up at <100 mA
The feature set of the TPS2044 and TPS2054 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 33).