Datasheet

IN1
OC1
EN1
OC2
EN2
GND
0.1 µF
2
16
3
13
4
15
14
33 µF
33 µF
GND
1
OUT1
OUT2
TPS2044B
Power Supply
D+
D−
V
BUS
GND
D+
D−
V
BUS
Downstream
USB Ports
USB
Controller
3.3 V 5 V
OC3
EN3
OC4
EN4
12
7
9
8
6
IN2
+
+
5
GND
11
10
33 µF
33 µF
GND
OUT3
OUT4
D+
D−
V
BUS
GND
D+
D−
V
BUS
+
+
TPS2041B, TPS2042B
TPS2043B, TPS2044B, TPS2051B
TPS2052B, TPS2053B, TPS2054B
www.ti.com SLVS514L –JUNE 2010– REVISED JUNE 2011
Figure 34. Typical Four-Port USB Host / Self-Powered Hub
Bus-powered hubs 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 35).
Copyright © 2010–2011, Texas Instruments Incorporated 21