USB2524 datasheet(45/57 Pages) SMSC

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USB MultiSwitchTM Hub

Datasheet

SMSC USB2524

Revision 1.91 (08-22-07)

DATASHEET

8.3

Host Ownership and Port Speed LED Indication:

All 8 LED pins are used in this mode in conjunction with 8 Dual-color LEDs (each LED pair in a single

package) to indicate which upstream Host owns each specific downstream Port, as well as the speed

that the downstream device is operating at.

Each dual-color LED provides two separate colors (commonly Green and Red). If each of these

separate colors are pulsed on and off at a rapid rate, a user will see a third color (in this example,

Orange). By this means, 4 different “color” states are possible (Green, Red, Orange, and Off).

Figure 8.1 Dual Color LED Implementation Example

Figure 8.1 shows a simple example of how this LED circuit will be implemented. The Circuit will need

to be replicated for each of the 8 LED pins on the USB2524. In this circuit, when the LED pin is driven

to a logic low state, the Green LED will Light up. When the LED pin is driven to a Logic High state

the Red LED will Light up. When a 1KHz square wave is driven out on the LED pin, the Green and

Red LED’s will both alternately light up giving the effect of the color Orange. When nothing is driven

out on the LED pin (i.e. the pin floats to a “tri-state” condition), neither the Green or Red LED will light

up, this is the “Off” state.

LED pin

Green LED

Red LED

3.3V

General

Purpose

Diode

Current limiting

resistor

Connect to other

dual color diodes.

USB2524 数据表(PDF) 45 Page - SMSC Corporation