TPS2070, TPS2071

FOUR-PORT USB HUB POWER CONTROLLERS

SLVS287A – SEPTEMBER 2000 – REVISED FEBRUARY 2001

25

POST OFFICE BOX 655303

APPLICATION INFORMATION

USB hybrid hub

A USB hybrid hub can be simply implemented using the TPS2071 USB power controller and a TUSB2046 USB

hub controller as shown in Figure 38. The TPS2071 USB power controller provides all the power needs to the

four downstream ports and meets all the USB power specifications for both self-powered hubs and bus-powered

hubs. The power controllers integrated 3.3-V LDO is used to provide power for the hub controller and any other

local functions (e.g. transient suppressor SN75240 ), which saves board space and cost. The TPS2071 also

provides the hub controller with a power good (PG) signal that connects to the RESET input of the hub controller

to automatically reinitialize the hub when switching between self-powered mode and bus-powered mode

whenever the self-power supply is connected or disconnected. The amount of time in which the hub controller

is kept in a reset state is controlled by a capacitor connected between the PG_DLY pin of the power controller

and ground.

By using an external N-channel MOSFET and the TPS2071 internal voltage-regulator controller, a regulated

5-V self-powered source can be generated from an input voltage range of 6 V to 9 V (see Figure 38). In this

configuration, the internal voltage regulator controller is enabled by connecting the EN_REG input to the BP

input. Using the internal voltage regulator controller also requires connecting a 0.01

µF capacitor between CP_P

and CP_M of the TPS2071 power controller. Also, a 0.1-

µF capacitor is needed between VCP of the power

controller and ground.