LTC4292 datasheet(24/44 Pages) AD

24 / 44 page

LTC9101-2/LTC9102

Rev. 0

For more information www.analog.com

APPLICATIONS INFORMATION

Table 10. Type 3 and Type 4 PD Classifications by

PD Configuration

SINGLE-SIGNATURE PDs

DUAL-SIGNATURE PDs

CLASS

PD AVAILABLE

POWER

CLASS

CHANNEL AVAILABLE

POWER*

Class 1

3.84W

Class 1

3.84W

Class 2

6.49W

Class 2

6.49W

Class 3

13W

Class 3

13W

Class 4

25.5W

Class 4

25.5W

Class 5

40W

Class 5

35.6W

Class 6

51W

Class 7

62W

Class 8

71.3W

*Dual-signature PD total available power is the sum of both channels

available power. Class signatures may differ between channels of a port,

e.g., Class 3 + Class 4 = 13W + 25.5W = 38.5W.

802.3bt Classification of Single-Signature PDs

Type 3 and Type 4 PSEs issue a single classification event

(see Figure 17) to Class 0 through 3 single-signature (SS)

PDs. A Class 0 through 3 SS PD presents its class signa-

ture to the PSE and is then powered on if sufficient power

is available. Power limited 802.3bt PSEs may also issue a

single classification event to Class 4 and higher SS PDs in

order to demote those PDs to 13W. See Figure 17.

Type 3 and 4 PSEs present three classification events

to Class 4 SS PDs (see Figure 18) if sufficient power is

available. Class 4 SS PDs present class signature 4 on

all events. The third event differentiates a Class 4 SS PD

from a higher Class SS PD. Power limited IEEE 802.3bt

PSEs may issue three classification events to Class 5 and

higher SS PDs in order to demote those PDs to 25.5W.

Type 3 and 4 PSEs present four classification events (see

Figure 19) to Class 5 and 6 SS PDs if sufficient power is

available. Class 5 and 6 SS PDs present class signature 4

on the first two events. Class 5 and 6 SS PDs present class

signature 0 or 1, respectively, on the subsequent events.

Power limited PSEs may issue four events to Class 7 and 8

SS PDs in order to demote those PDs to 51W.

9101-2 F17

VCLASSMIN

VMARKMAX

VSIGMIN

VRESET

DETECT

1ST

CLASS

1ST

MARK

POWER ON

Figure 17. Type 3 or 4 PSE, 1-Event Class Sequence

9101-2 F18

VCLASSMIN

VMARKMAX

VSIGMIN

VRESET

DETECT

1ST

CLASS

1ST

MARK

2ND

MARK

3RD

MARK

2ND

CLASS

3RD

CLASS

POWER ON

Figure 18. Type 3 or 4 PSE, 3-Event Class Sequence

9101-2 F19

VCLASSMIN

VMARKMAX

VSIGMIN

VRESET

DETECT

1ST

CLASS

1ST

MARK

2ND

MARK

3RD

MARK

4TH

MARK

2ND

CLASS

3RD

CLASS

4TH

CLASS

POWER ON

Figure 19. Type 3 or 4 PSE, 4-Event Class Sequence

9101-2 F20

VCLASSMIN

VMARKMAX

VSIGMIN

VRESET

DETECT

1ST

CLASS

1ST

MARK

2ND

MARK

3RD

MARK

4TH

MARK

5TH

MARK

2ND

CLASS

3RD

CLASS

4TH

CLASS

5TH

CLASS

POWER ON

Figure 20. Type 4 PSE, 5-Event Class Sequence

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