TUSB2040A

4-PORT HUB FOR THE UNIVERSAL SERIAL BUS

WITH OPTIONAL SERIAL EEPROM INTERFACE

SLLS288B – JANUARY 1998 – REVISED MARCH 1998

14

POST OFFICE BOX 655303

APPLICATION INFORMATION

self-powered hub, individual port power management

A self-powered TUSB2040A is capable of supplying 500 mA of current for low-power or high-power device class

functions to each downstream port. Self-powered hubs are required to implement overcurrent protection.

Individual port-power management (see Figure 12) utilizes the TPS2014 power switching and overcurrent

protection that provide maximum robustness to the hub system. When the hub detects a downstream port fault,

power is removed from the faulty port only, thus allowing other ports to continue normal operation. Individual

SN75240 transient suppressors reduce in-rush current and voltage spikes. The TPS7133 low-dropout regulator

provides a power good (PG) signal for reset at power up.

48-MHz Clock

Signal‡

BUSPWR/SCL

GANGED/SDA

DP1

DM1

DP2

DM2

DP3

DM3

DP4

PWRON1

PWRON2

PWRON3

PWRON4

OVRCUR1

OVRCUR2

OVRCUR3

OVRCUR4

DM4

DP0

DM0

VCC

GND

XTAL1

XTAL2

EXTMEM

RESET

5 V

3.3 V

GND

D +

D –

Upstream

Port

TPS7133†

SN75240†

EN

IN

OC OUT

D +

D –

5 V

GND

D +

D –

5 V

D +

D –

5 V

D +

D –

5 V

3.3 V

Downstream

Ports

5-V Board Power

Supply

TUSB2040A

TPS2014†

A

B

C

D

120

µF§

SN75240†

A

B

C

D

GND

GND

GND

0.1

µF

EN

IN

OC OUT

TPS2014†

0.1

µF

EN

IN

OC OUT

TPS2014†

0.1

µF

EN

IN

OC OUT

TPS2014†

0.1

µF

120

µF§

120

µF§

120

µF§

Figure 12. TUSB2040A Self-Powered Hub, Individual 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.

SN75240†

A

B

5 V

GND

C

D

4.7

µF

0.1

µF

4.7

µF

PG