USB2524 datasheet(13/57 Pages) SMSC

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USB MultiSwitchTM Hub

Datasheet

SMSC USB2524

Revision 1.91 (08-22-07)

DATASHEET

Port [2:1] Green

LED

Port Non-

Removable

strapping option

LED_A[2:1]_N/

NON_REM[1:0]

I/O12

Green indicator LED for ports 2 and 1. Will be active low

when LED support is enabled via EEPROM or SMBus.

If the hub is configured by the internal default configuration,

these pins will be sampled at RESET_N negation to

determine if ports [3:1] contain permanently attached (non-

removable) devices. Also, the active state of the LED's will

be determined as follows:

NON_REM[1:0] = '00', All ports are removable,

LED_A2_N is active high,

LED_A1_N is active high.

NON_REM[1:0] = '01', Port 1 is non-removable,

LED_A2_N is active high,

LED_A1_N is active low.

NON_REM[1:0] = '10', Ports 1 & 2 are non-removable,

LED_A2_N is active low,

LED_A1_N is active high.

NON_REM[1:0] = '11', Ports 1, 2, & 3 are non-removable,

LED_A2_N is active low,

LED_A1_N is active low.

Enhanced Port

LED Indicators

LED_B[4:1]_N

I/O12

These 4 pins in conjunction with the LED_A[4:1]_N pins

provides a total of 8 LED pins which are used to indicate

upstream host ownership of the downstream ports.

2 operational modes are available

Single Color LED Mode: LED will light to show which host

owns each of the downstream ports. If a port is

“unassigned” then neither LED for that port will light up.

Dual Color LED’s: (note; 4 possible states are displayed to

the user, Green, Red, Orange and Off).

Port Power

Polarity strapping

PRTPWR_POL

I/O

Port Power Polarity strapping determination for the active

signal polarity of the PRTPWR[4:1] pins.

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

(through the use of internal combinatorial logic) determine

the active state of the PRTPWR[4:1] 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 the

PRTPWR[4:1] pins.

‘1’ = PRTPWR[4:1] pins have active ‘high’ polarity

‘0’ = PRTPWR[4:1] pins have active ‘low’ polarity

Warning: Active Low port power controllers may glitch

the downstream port power when system power is first

applied. Care should be taken when designing with

active low components!

Over Current

Sense

OCS[4:1]_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.

Table 4.1 Switching Hub Pin Descriptions (continued)

NAME

SYMBOL

TYPE

FUNCTION

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