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USB2504

Integrated USB 2.0 Compatible 4-Port Hub

SMSC -> Microchip 

Integrated USB 2.0 Compatible 4-Port Hub

Datasheet

Table 4.1 4-Port Hub Pin Descriptions (continued)

NAME

SYMBOL

TYPE

FUNCTION

Port 4 Amber

LED

&

LED Enable

strapping option

AM4/

LED_EN

Port 3 Amber

LED

Port 2 Amber

LED

&

MTT Disable

AM3

AM2/

MTT_EN

Port 1 Amber

LED

&

Gang Power

Switching and

Current Sensing

strapping option.

AM1/

GANG_EN

Port Power

PRTPWR_POL

Polarity strapping.

Over Current

Sense

USB Transceiver

Bias

OCS[4:1]_N

RBIAS

I/O12

I/O12

I/O12

I/O12

I/O12

IPU

I-R

Amber indicator LED for port 4. Will be active low when LED

support is enabled via EEPROM or SMBus.

If the hub is configured by the internal default configuration,

this pin will be sampled at RESET_N negation to determine

if LED support is enabled or disabled. Also, the active state

of the LED will be determined as follows:

‘0’ = LED support is disabled, LED is inactive

‘1’ = LED Support is enabled, LED is active low.

Amber indicator LED for port 3. Signal will be active low.

Amber indicator LED for port 2. Will be active low when LED

support is enabled via EEPROM or SMBus.

If the hub is configured by the internal default configuration,

this pin will be sampled at RESET_N negation to determine

if MTT support is disabled (STT only). Also, the active state

of the LED will be determined as follows:

‘0’ = MTT support is disabled, LED is active high

‘1’ = MTT support is enabled, LED is active low.

Amber indicator LED for port 1, Will be active low when LED

support is enabled via EEPROM or SMBus.

If the hub is configured by the internal default configuration,

this pin will be sampled at RESET_N negation to determine

if downstream port power switching and current sensing are

ganged, or individual port-by-port. Also, the active state of

the LED will be determined as follows:

‘0’ = Port-by-port sensing & switching, LED is active high

‘1’ = Ganged sensing & switching, LED is active low.

Port Power Polarity strapping determination for the active

signal polarity of the [4:1]PRTPWR 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 [4:1]PRTPWR pins in order to ensure

that downstream port power is not inadvertently enabled to

inactive ports during a hardware reset.

On the rising edge of RESET_N (see the applicable

RESET_N timing table in Section 5.6.1), the logic value will

be latched internally, and will retain the active signal polarity

for the PRTPWR[4:1] pins.

‘1’ = PRTPWR[4:1]_P/N pins have an active ‘high’ polarity

‘0’ = PRTPWR[4:1]_P/N 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.

Revision 2.3 (08-27-07)

12

DATASHEET

SMSC USB2504/USB2504A

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