USB 2.0 7-Port Hub

Data Sheet Rev. 1.01

Power Control and Over-current Protection

The FE2.1 supports optional power switches that control delivery of power downstream facing ports by

way of a set of active low, open drain, control pins, PWRJ[7:1]. With external pull-up resisters to either

5V or 3.3V, system designers could choice from a wide variety of circuit to implement the power

switches.

As self-powered hub, over-current protection is a must for safety reasons. The FE2.1 provides a set of

input pins, OVCJ[7:1], to monitor status of external over-current detection circuit. The over-current

status will than be reported to the host hub driver by FE2.1. Depends on the power control mode

actually selected, the unused OVCJ pins will be internally pull-up and left unconnected on board.

The FE2.1 supports three types of power control modes, namely Individual Mode, Multiple Gangs

Mode, and Ganged Mode. These modes could be configured by tying either or both of PWRJ[7:6] to

ground according to the following table.

Power

Control Mode

PWRJ[7] PWRJ[6]

wHubCharacteristics

PWRJ

[

N]

OVCJ

[

N]

Availability

D1..D0

D4..D3

Individual

Mode

Normal

Normal

01

01

1, 2, 3, 4,

5, 6, 7

1, 2, 3, 4,

5, 6, 7

LQFP-64

Multiple

Gangs Mode

Tied-to-

Ground

Normal

00

01

1

1, 5

LQFP-64,

LQFP-48

Ganged Mode Tied-to-

Ground

Tied-to-

Ground

00

00

1

1

LQFP-64

In the Individual Mode, the power switch of each port is controlled individually, and the over-current

status is reported on a per-port basis. That is, for each port

N, the power switch is controlled by

PWRJ[

N], and the over-current status is monitored by OVCJ[N].

In the Ganged Mode, the power switch to all ports are controlled by one single PWRJ[1], and the over-

current is monitored by OVCJ[1]. Therefore, when host issues SetPortFeature(PORT_POWER) to

any of the downstream facing port, the PWRJ[1] will go active, and only when all ports are in powered-

off state that PWRJ[1] will be turned inactive. Since there is only one OVCJ input, all downstream

facing ports will be marked as over-current simultaneously and set to powered-off state.

The Multiple Gangs Mode has one more over-current status pin, OVCJ[5], then the Ganged Mode. If

Jul. 16, 2009

Subject to Change Without Notice

12