Datasheet

TPS2041A, TPS2042A, TPS2043A, TPS2044A
TPS2051A, TPS2052A, TPS2053A, TPS2054A
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS247 – SEPTEMBER 2000
23
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
low-power bus-powered functions and high-power bus-powered functions
Both low-power and high-power bus-powered functions obtain all power from upstream ports; low-power
functions always draw less than 100 mA; high-power functions must draw less than 100 mA at power up and
can draw up to 500 mA after enumeration. If the load of the function is more than the parallel combination of
44 Ω and 10 µF at power up, the device must implement inrush current limiting (see Figure 28).
IN
OC
EN
GND
0.1 µF
2,3
5
4
6, 7, 8
0.1 µF 10 µF
GND
1
OUT
TPS2041A
Power Supply
D+
D–
V
BUS
USB
Control
3.3 V
10 µF
Internal
Function
Figure 28. High-Power Bus-Powered Function (Example, TPS2041A)
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 TPS204xA and TPS205xA 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 Figures 29 through 32).