TUSB2046A

4-PORT HUB FOR THE UNIVERSAL SERIAL BUS

WITH OPTIONAL SERIAL EEPROM INTERFACE

SLLS404 – DECEMBER 1999

12

POST OFFICE BOX 655303

APPLICATION INFORMATION

bus-powered hub, ganged port power management

When used in bus-powered mode, the TUSB2046A supports up to four downstream ports by controlling a

TPS2041 device which is capable of supplying 100 mA of current to each downstream port. Bus-powered hubs

must implement power switching to ensure current demand is held below 100 mA when the hub is hot-plugged

into the system. Utliizing the TPS2041 for ganged power management provides over-current protection for the

downstream ports. The SN75240 transient suppressors reduce inrush current and voltage spikes on the data

lines. The OVRCUR signals should be tied together for a ganged operation.

Figure 9. TUSB2046A Bus-Powered Hub, Ganged Port Power Management Application

† TPS2041 and SN75240 are Texas Instruments devices.

‡ 120

µF per hub is the minimum required per the USB specification, version 1.1. However, TI recommends a 100 µF low ESR tantulum capacitor

per port for immunity to voltage droop.

§ LDO is a 5 V to 3.3 V voltage regulator

DP1

DM1

DP2

DM2

DP3

DM3

DP4

PWRON1

PWRON2

PWRON3

PWRON4

OVRCUR1

OVRCUR2

OVRCUR3

OVRCUR4

DM4

DP0

DM0

VCC

XTAL1

XTAL2

EXTMEM

RESET

SN75240†

EN

IN

OC

OUT

D +

D –

5 V

GND

D +

D –

5 V

D +

D –

5 V

D +

D –

5 V

Downstream

Ports

TUSB2046A

TPS2041†

A

B

C

D

100

SN75240†

A

B

C

D

GND

GND

GND

1

µF

100

100

100

5 V

3.3 V

GND

D +

D –

Upstream

Port

SN75240†

A

B

5 V

GND

C

D

4.7

µF

0.1

µF

4.7

µF

GND

Ferrite Beads

Ferrite Beads

Ferrite Beads

Ferrite Beads

EEDATA/GANGED

6-MHz Clock

Signal

BUSPWR

3.3 V

System

Power-On Reset

OUT

OUT

IN

3.3 V

3.3 V

1.5 k

Ω

15 k

Ω

15 k

Ω

15 k

Ω

15 k

Ω

15 k

Ω

15 k

Ω

15 k

Ω

15 k

Ω