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FUNCTIONAL DESCRIPTION

TUSB2551

ADVANCED UNIVERSAL SERIAL BUS TRANSCEIVER

SCES667 – FEBRUARY 2008

TERMINAL FUNCTIONS

TERMINAL

I/O

DESCRIPTION

RGT

PW

NAME

NO.

NO.

System interface supply voltage. Used to provide reference supply voltage for system I/O

15

1

I

interface signaling.

Speed. Edge-rate control: A logic HIGH operates at edge rates for full-speed operation. A

SPEED

1

2

I

logic LOW operates at edge rates for low-speed operation.

RCV

2

3

O

Receive data. Output for USB differential data.

If OE = 1, VP = Receiver output (+)

VP

3

4

I/O

If OE = 0, VP = Driver input (+)

If OE = 1, VM = Receiver output (–)

VM

4

5

I/O

If OE = 0, VM = Driver input (–)

SOFTCON

5

6

I

GND

6

7

Ground reference

SUSPEND

7

8

I

Suspend. Active high. Turns off internal circuits to reduce supply current.

NC

8, 16

No internal connection

Output enable. Active low. Enables the transceiver to transmit data onto the bus. When

OE

9

9

I

inactive, the transceiver is in the receive mode.

D–, D+

10, 11

10, 11

I/O

Differential data lines conforming to the USB standard

3.3-V reference supply. Requires a minimum 0.1-

µF decoupling capacitor for stability. A

12

12

O

1-

µF capacitor is recommended.

Pullup supply voltage. Used to connect 1.5-k

Ω pullup speed detect resistor. If SOFTCON =

13

13

O

14

14

I

USB bus supply voltage. Used to power USB transceiver and internal circuitry.

FUNCTION SELECTION

SUSPEND

OE

D+, D–

RCV

VP, VM

FUNCTION

0

0

Driving

Active

Active

Normal transmit mode

0

1

Receiving

Active

Active

Normal receive mode

1

0

Hi-Z

0

Not active

Low power state

1

1

Hi-Z

0

Active

(1)

During suspend, VP and VM are active in order to detect out-of-band signaling conditions.

TRUTH TABLE DURING NORMAL MODE

OE = 0

INPUT

OUTPUT

RESULT

VP

VM

D+

D–

RCV

0

0

0

0

SE0

0

1

0

1

0

Logic 0

1

0

1

0

1

Logic 1

1

1

1

1

Undefined

OE = 1

Input

Output

RESULT

D+

D–

VP

VM

RCV

0

0

0

0

SE0

0

1

0

1

0

Logic 0

1

0

1

0

1

Logic 1

1

1

1

1

Undefined

(1)

X = Undefined

Copyright © 2008, Texas Instruments Incorporated

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Product Folder Link(s): TUSB2551