Datasheet

 
 
SLVS399A − JANUARY 2002 − REVISED MAY 2006
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APPLICATION INFORMATION
USB power-distribution requirements (continued)
The feature set of the TPS2140/41/50/51 allows them to meet the requirements of functions. The integrated
current-limiting is required by hubs and peripheral functions. 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.
USB applications
Figure 27 shows the TPS2151 being used in a USB bus-powered peripheral design. The internal 3.3-V LDO
is used to provide power for the USB function controller as well as to the 1.5-kΩ pullup resistor. One example
of USB bus-powered peripheral applications is the USB ADSL modem, which needs several power rails and
power sequencing.
LDO
LDO_PLDN
LDO_OUT
ADJ
USB
Function
Controller
LDO_PG
LDO_IN
LDO_EN
SW_OUT
SW_PLDN
SW_PG
Switch
1.5 kΩ
D+
D−
GND
5 V
TPS2151
SW_IN
5 V
Circuitry
0.1 µF4.7 µF
3.3 V
Circuitry
0.1 µF
3.3 V
10 µF
SW_EN
0.1 µF
C
†
†
C can be very high-value capacitance
Figure 27. Bus-Powered USB Peripheral Application