Micrel, Inc.

MIC2358YLQ

July 2010

21

M9999-070810

Port Voltage Register

SMBus Address: 0x04, 0x0C, 0x14, 0x1C, 0x24, 0x2C, 0x34, 0x3C

Read Only

The Voltage register holds the 8-bit value of the measured port voltage. The LSB is equivalent to 0.25V. The register is

only valid if the monitor bit of the port option register is set; otherwise it reads as 0x00.

Port Current Register

SMBus Address: 0x05, 0x0D, 0x15, 0x1D, 0x25, 0x2D, 0x35, 0x3D

Read Only

The Current register holds the 8-bit value of the measured port current. The LSB is equivalent to 2mA. The register is

only valid if the monitor bit of the port OPTION register is set; otherwise it reads as 0x00.

Port Status Register

SMBus Address: 0x06, 0x0E, 0x16, 0x1E, 0x26, 0x2E, 0x36, 0x3E

Read Only

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

–

pse_status

pd_class

Name

Description

pse_status

Indicates the port PSE Status bits from the Table 33-16 of

IEEE Std 802.3af

. Possible values are shown below

pd_class

Indicates the class of a detected PD. Possible values are shown below. (Note 1)

PSE Status

Status

Value

Disabled

000

Searching

001

Delivering Power

010

Test mode

011

Test error

100

Implementation specific fault

101

Reserved

110

Reserved

111

PD Class

Class

Value

Class 0

000

Class 1

001

Class 2

010

Class 3

011

Class 4

100

Note:

1. Per IEEE Std 802.3af, PD class defaults to 0 if classification is disabled.