USB 2.0 7-Port Hub

Data Sheet Rev. 1.01

The LED[7:1] pins could also be used to configure the number of downstream facing port and non-

removable downstream devices. These option selections are sampled and loaded each time after chip

reset. If an alternate configuration is intended, the corresponding pins should be tied to ground as

shown in the following table. Otherwise, denoted as Normal in the following tables, they could be

either left floating or connected to the LED's as shown by figure 4.

Usable Downstream

Facing Port

LED[7]

LED[6]

4, 3, 2, 1

Tied-to-Ground

Tied-to-Ground

5, 4, 3, 2, 1

Normal

Tied-to-Ground

6, 5, 4, 3, 2, 1

Tied-to-Ground

Normal

7, 6, 5, 4, 3, 2, 1

Normal

Normal

Setting the number of Downstream Facing Port by tying any of LED[7:6] to ground will change the

bNbrPorts field (3rd byte) of Hub Descriptor as response to host's GetHubDescriptor request.

Henceforth the ports beyond the specified number will not be recognized nor activated by the host.

Non-Removable

Downstream Facing

Ports

LED[4]

LED[3]

LED[2]

None

Normal

Normal

Normal

2

Normal

Normal

Tied-to-Ground

3, 2

Normal

Tied-to-Ground

Normal

3, 2, 1

Normal

Tied-to-Ground

Tied-to-Ground

4, 3, 2, 1

Tied-to-Ground

Normal

Normal

5, 4, 3, 2, 1

Tied-to-Ground

Normal

Tied-to-Ground

6, 5, 4, 3, 2, 1

Tied-to-Ground

Tied-to-Ground

Normal

7, 6, 5, 4, 3, 2, 1

Tied-to-Ground

Tied-to-Ground

Tied-to-Ground

The Non-Removable Downstream Facing Ports setting is reported in the bit-map of DeviceRemovable

field of Hub Class Descriptor.

When a downstream facing port is configured as unusable or non-removable, its corresponding LED pin

will be disabled. In other words, those LED pins should be either tied to ground based on the selected

configuration, or left floating. The only exception is LED[1], which would be still used as SCL, Serial

Clock pin for external EEPROM, should it exist.

Jul. 16, 2009

Subject to Change Without Notice

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