TPS2061, TPS2062, TPS2063
TPS2065, TPS2066, TPS2067
www.ti.com
SLVS490B–DECEMBER 2003–REVISED DECEMBER 2004
APPLICATION INFORMATION (continued)
Downstream
USB Ports
D+
D−
V
BUS
0.1 µF
33 µF
GND
Power Supply
3.3 V
5 V
D+
D−
TPS2062
2
8
IN
7
V
BUS
OUT1
0.1 µF
0.1 µF
33 µF
GND
OC1
EN1
OC2
EN2
3
5
USB
Controller
D+
D−
4
6
V
BUS
OUT2
0.1 µF
33 µF
GND
GND
1
D+
D−
V
BUS
0.1 µF
33 µF
GND
Figure 27. Typical Four-Port USB Host / Self-Powered Hub
BPHs obtain all power from upstream ports and often contain an embedded function. The hubs are required to
power up with less than one unit load. The BPH usually has one embedded function, and power is always
available to the controller of the hub. If the embedded function and hub require more than 100 mA on power up,
the power to the embedded function may need to be kept off until enumeration is completed. This can be
accomplished by removing power or by shutting off the clock to the embedded function. Power switching the
embedded function is not necessary if the aggregate power draw for the function and controller is less than one
unit load. The total current drawn by the bus-powered device is the sum of the current to the controller, the
embedded function, and the downstream ports, and it is limited to 500 mA from an upstream port.
LOW-POWER BUS-POWERED 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). With TPS206x, the
internal functions could draw more than 500 mA, which fits the needs of some applications such as motor driving
circuits.
19
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