AS1124 datasheet(11/21 Pages) ETC2

11 / 21 page

AS1124

Akros Silicon, inc.

6399 San Ignacio Avenue, Suite 250, San Jose, CA 95119 USA

408.746.9000



www.AkrosSilicon.com

POWER FEED ALTERNATIVES FOR

10/100 ETHERNET SYSTEMS

Figure 14 illustrates the two power feed options allowed in

the 802.3af standard for 10/100 systems. In Alternative A,

a PSE powers the end station by feeding power along the

twisted pair cable used for the 10/100 Ethernet signal via

the center taps of Ethernet transformers. On the line side

of the transformers for the PD, power is delivered through

pins 1 and 2 and returned through pins 3 and 6. In

Alternative B, a PSE powers the end station by feeding

power through the cable pairs not used for 10/100 data

transmission. Power is delivered through pins 4, 5, 7and 8

without transformers.

Figure 14 – IEEE® Std. 802.3af-2003 Power Schemes for 10/100 Systems

The IEEE® Std. 802.3af-2003 is intended to be fully

compliant with all existing non- powered Ethernet

systems. As a result, the PSE is required to detect via

a well-defined procedure whether or not the connected

device is PD compliant and classifies the needed

power prior to applying power to the system. Maximum

allowed voltage is 57V to stay within SELV (Safety

Extra Low Voltage) limits.

AS1124 Datasheet(PDF) 11 Page - List of Unclassifed Manufacturers