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USB2503A

Integrated USB 2.0 Compatible 3-Port Hub

SMSC -> Microchip 

Integrated USB 2.0 Compatible 3-Port Hub

Datasheet

Table 4.1 3-Port Hub Pin Descriptions (continued)

NAME

SYMBOL

Port Power

PRTPWR_POL

Polarity strapping.

Over Current

Sense

USB Transceiver

Bias

OCS[3:1]_N

RBIAS

Serial Data/SMB

Data

Serial Clock/SMB

Clock

&

Chip Select /

EEPROM Select

SMB

Programming

Select

SDA/SMBDATA

SCL/SMBCLK/

CFG_SEL0

CFG_SEL1

TYPE

FUNCTION

I/O12

IPU

I-R

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

Input from external current monitor indicating an over-

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

supply}

A 12.0kΩ (+/− 1%) resistor is attached from ground to this

pin to set the transceiver’s internal bias settings.

SERIAL PORT INTERFACE

IOSD12 (Serial Data)/(SMB Data) signal.

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.

I

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.

CFG_SEL1

0

1

1

Table 4.2 SMBus or EEPROM Interface Behavior

CFG_SEL0 SMBus or EEPROM interface behavior.

X

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

descriptors. SMBus slave address is :0101101

0

Internal Default Configuration via strapping options.

1

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

functionality.

NAME

Crystal

Input/External

Clock Input

SYMBOL

XTAL1/

CLKIN

SMSC USB2503/USB2503A

Table 4.3 Miscellaneous Pins

TYPE

ICLKx

FUNCTION

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.

11

DATASHEET

Revision 2.3 (08-27-07)

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