LTC4265 LINER [Linear Technology], LTC4265 Datasheet - Page 15

• Manufacturer Part Number: LTC4265
• Description: IEEE 802.3at High Power PD Interface Controller with 2-Event Classifi cation Recognition
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
T2PSE Interface
When a 2-event Classifi cation sequence successfully
completes, the LTC4265 recognizes this sequence, and
provides an indicator bit, declaring the presence of a
Type-2 PSE. The open drain output provides the option
to use this signal to communicate to the LTC4265 load,
or to leave the pin unconnected.
PSE
PSE
PSE
TO
TO
TO
–54V
–54V
–54V
Figure 8. Power Good Interface Examples
V
V
V
IN
IN
IN
LTC4265
LTC4265
LTC4265
ACTIVE-HIGH ENABLE
PWRGD
PWRGD
PWRGD
ACTIVE-LOW ENABLE
V
V
V
GND
GND
GND
OUT
OUT
OUT
ACTIVE-LOW ENABLE
MMBZ5231B
MMBD4148
5.1V
R9
100k
R10
100k
10k
10k
R
D9
R
D9
RUN
S
S
LOAD
PD
SHDN
LOAD
Q1
FMMT2222
PD
4265 F08
LOAD
PD
V
+
Figure 9 shows two interface options using the T2PSE
pin and the opto-isolator. The T2PSE pin is active low and
connects to an opt-isolater to communicate across the
DC/DC converter isolation barrier. The pull up resistor R
is sized according to the requirements of the opto-isolator
operating current, the pull-down capability of the T2PSE
pin, and the choice of V
the PoE supply rail (which the LTC4265 GND is tied to), or
from the voltage source that supplies power to the DC/DC
converter. Option 1 has the advantage of not drawing power
unless T2PSE is declared active.
OPTION 2: SHUNT CONFIGURATION FOR ACTIVE HIGH/OPEN COLLECTOR OUTPUT
OPTION 1: SERIES CONFIGURATION FOR ACTIVE LOW/LOW IMPEDANCE OUTPUT
PSE
PSE
TO
TO
–54V
–54V
Figure 9. T2PSE Interface Examples
V
V
IN
IN
LTC4265
LTC4265
+
T2PSE
T2PSE
. V
V
GND
GND
OUT
+
for example can come from
V
V
+
+
R
R
P
P
LTC4265
TO PD LOAD
TO PD LOAD
4265 F09
15
4265f
P