Datasheet

USB 2.0 Hi-Speed 7-Port Hub Controller
Datasheet
SMSC USB2517 17 Revision 2.8 (09-17-12)
DATASHEET
Chapter 6 LED Usage Description
6.1 LED Functionality
The hub supports 2 different (mutually exclusive) LED modes. The USB Mode provides 14 LED’s that conform to the
USB 2.0 specification functional requirements for Green and Amber LED’s. The LED Mode “Speed indicator” provides
the downstream device connection speed.
6.1.1 USB Mode 14-Wire
The LED_A[7:1]_N pins are used to provide Green LED support as defined in the USB 2.0 specification. The
LED_B[7:1]_N pins are used to provide Amber LED support as defined in the USB 2.0 specification. The USB
Specification defines the LED’s as port status indicators for the downstream ports. Please note that no indication of
port speed is possible in this mode. The pins are utilized as follows:
LED_A1_N = Port 1 green LED
LED_A2_N = Port 2 green LED
LED_A3_N = Port 3 green LED
LED_A4_N = Port 4 green LED
LED_A5_N = Port 5 green LED
LED_A6_N = Port 6 green LED
LED_A7_N = Port 7 green LED
LED_B1_N = Port 1 amber LED
LED_B2_N = Port 2 amber LED
LED_B3_N = Port 3 amber LED
LED_B4_N = Port 4 amber LED
LED_B5_N = Port 5 amber LED
LED_B6_N = Port 6 amber LED
LED_B7_N = Port 7 amber LED
6.1.2 LED Mode Speed Indication
The LED_A[7:1]_N pins are used to provide connection status as well as port speed by using dual color LED's. This
scheme requires that the LED's be in the same package, and that a third color is produced so that the user percieves
both LED's as being driven "simultaneously".
The LED_A[7:1] pins used in this mode are connected to 7 dual color LED’s (each LED pair in a single package).
These pins indicate the USB speed of each attached downstream device.
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). Using this method, 4 different
"color" states are possible (Green, Red, Orange, and Off).