TPS2041B, TPS2042B
TPS2043B, TPS2044B, TPS2051B
TPS2052B, TPS2053B, TPS2054B
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SLVS514G–APRIL 2004–REVISED OCTOBER 2006
APPLICATION INFORMATION (continued)
Power Supply
3.3 V
D+
D−
TPS2042B
2
8
IN
V
BUS
7
10 µF
0.1 µF
Internal
OUT1
GND
Function
0.1 µF
10 µF
OC1
EN1
OC2
EN2
3
5
USB
Control
6
4
OUT2
GND
Internal
Function
0.1 µF
10 µF
1
Figure 32. High-Power Bus-Powered Function (Example, TPS2042B)
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 VBUS
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 TPS204xB/TPS205xB 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-powered hubs, as well as the input
ports for bus-powered functions (see Figure 33 through Figure 36).
22
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