USB2503 datasheet(11/43 Pages) SMSC

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Integrated USB 2.0 Compatible 3-Port Hub

Datasheet

SMSC USB2503/USB2503A

Revision 2.3 (08-27-07)

DATASHEET

Port Power

Polarity strapping.

PRTPWR_POL

I/O12

Port Power Polarity strapping determination for the active

signal polarity of the PRTPWR[3:1] pins.

While RESET_N is asserted, the logic state of this pin will

(though the use of internal combinatorial logic) determine

the active state of the PRTPWR[3:1] pins in order to ensure

that downstream port power is not inadvertently enabled to

inactive ports during a hardware reset.

When RESET_N is negated, the logic value will be latched

internally, and will retain the active signal polarity for

PRTPWR[3:1] pins.

‘1’ = PRTPWR[3:1] pins have an active ‘high’ polartity

‘0’ = PRTPWR[3:1] pins have an active ‘low’ polarity

Over Current

Sense

OCS[3:1]_N

IPU

Input from external current monitor indicating an over-

current condition. {Note: Contains internal pull-up to 3.3V

supply}

USB Transceiver

Bias

RBIAS

I-R

A 12.0k

Ω (+/− 1%) resistor is attached from ground to this

pin to set the transceiver’s internal bias settings.

SERIAL PORT INTERFACE

Serial Data/SMB

Data

SDA/SMBDATA

IOSD12

(Serial Data)/(SMB Data) signal.

Serial Clock/SMB

Clock

Chip Select /

EEPROM Select

SCL/SMBCLK/

CFG_SEL0

IOSD12

(Serial Clock)/(SMB Clock) signal. This multifunction pin is

read on the rising edge of RESET_N negation and will

determine the hub configuration method as described in

Table 4.2.

SMB

Programming

Select

CFG_SEL1

This pin is read on the rising edge of RESET_N negation

and will detemine the hub configuration method as

described in Table 4.2.

Table 4.2 SMBus or EEPROM Interface Behavior

CFG_SEL1

CFG_SEL0

SMBus or EEPROM interface behavior.

Configured as an SMBus slave for external download of user-defined

descriptors. SMBus slave address is :0101101

Internal Default Configuration via strapping options.

2-wire (I2C) EEPROMS are supported, and CFG_SEL0 has no other

functionality.

Table 4.3 Miscellaneous Pins

NAME

SYMBOL

TYPE

FUNCTION

Crystal

Input/External

Clock Input

XTAL1/

CLKIN

ICLKx

24MHz crystal or external clock input.

This pin connects to either one terminal of the crystal or

to an external 24MHz clock when a crystal is not used.

Table 4.1 3-Port Hub Pin Descriptions (continued)

NAME

SYMBOL

TYPE

FUNCTION

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