TUSB2040A

4-PORT HUB FOR THE UNIVERSAL SERIAL BUS

WITH OPTIONAL SERIAL EEPROM INTERFACE

SLLS288B – JANUARY 1998 – REVISED MARCH 1998

12

POST OFFICE BOX 655303

APPLICATION INFORMATION

bus-powered hub, ganged port power management

A bus-powered TUSB2040A supports up to four downstream ports and is capable of supplying 100 mA of

current for low-power device class functions to each downstream port. Bus-powered hubs must implement

power switching. Ganged power management (see Figure 10) utilizes the TPS2014 power switch device and

provides overcurrent protection for downstream ports. Individual SN75240 transient suppressors reduce

in-rush current and voltage spikes. The TPS7133 low-dropout voltage regulator provides a power good (PG)

signal for reset at power up. OVRCUR1 – OVRCUR4 inputs can be tied together for ganged mode operation.

Figure 10. TUSB2040A Bus-Powered Hub, Ganged Port Power Management Application

† TPS2014, TPS7133, and SN75240 are Texas Instruments devices.

‡ See Figures 7 and 8.

§ Minimum value required per USB specification, version 1.0.

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

TUSB2040A

TPS2014†

A

B

C

D

120

µF§

SN75240†

A

B

C

D

GND

GND

GND

1

µF

120

µF§

120

µF§

120

µF§

5 V

3.3 V

GND

D +

D –

Upstream

Port

TPS7133†

SN75240†

A

B

5 V

GND

C

D

4.7

µF

0.1

µF

4.7

µF

PG

GND

Ferrite Beads

Ferrite Beads

Ferrite Beads

Ferrite Beads

BUSPWR/SCL

GANGED/SDA

3.3 V

48-MHz Clock

Signal‡