Datasheet

IN
OC
5
3
4
1
0.1 µF 10 µF
Internal
Function
OUT
Power Supply
3.3 V
EN
0.1 µF
10 µF
USB
Control
GND
V
BUS
D−
D+
GND
2
TPS2041B
TPS2041B-EP
SLVSAX8 –SEPTEMBER 2011 www.ti.com
Low-Power 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 25).
Figure 25. High-Power Bus-Powered Function
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 TPS2041B 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 26).
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Product Folder Link(s): TPS2041B-EP