ltc4268cdkd-1-trpbf Linear Technology Corporation, ltc4268cdkd-1-trpbf Datasheet - Page 14

• Manufacturer Part Number: ltc4268cdkd-1-trpbf
• Description: High Power Pd With Synchronous Noopto Flyback Controller
• Manufacturer: Linear Technology Corporation

APPLICATIONS INFORMATION
The LTC4268-1 is specifi cally designed to implement
the high power PD front end and switching regulator for
power-hungry PoE applications that must operate beyond
the power limits of IEEE 802.3af. The LTC4268-1 uses
a precision, dual current limit that keeps inrush below
IEEE 803.2af levels to ensure interoperability with any
PSE. After inrush is complete, the LTC4268-1 input current
limit switches to the I
750mA power MOSFET. This allows a PD (supplied by a
custom PSE) to deliver power above the IEEE 802.3af
12.95W maximum, sending up to 35W to the PD load. The
LTC4268-1 uses established IEEE 802.3af detection and
LTC4268-1
14
3.3V
–54V
–54V
GND
GND
V
AUTO
DGND BYP
V
V
DD
EE
EE
0.25Ω
0.25Ω
SENSE GATE OUT
SENSE GATE OUT
LTC4259A
LTC4259A
AGND
1/4
1/4
IRLR3410
IRLR3410
0.1μF
DETECT
DETECT
AGND
10k
10k
CMPD3003
CMPD3003
S1B
S1B
LIMIT_HIGH
PSE
1k
1k
0.1μF
0.1μF
0.47μF
0.47μF
level, using an onboard,
Figure 1B. 4-Pair High Power PoE Gigabit Ethernet
Rx1
SMAJ58A
Rx2
SMAJ58A
Tx1
Tx2
1
2
3
6
4
5
7
8
RJ45
CAT5
classifi cation methods to maintain compliance and includes
an extended programmable Class 5 range for use in custom
PoE applications. The LTC4268-1 features both active-
high and active-low power good signaling for simplifi ed
interface to the converter. The SHDN pin on the LTC4268-1
can be used to provide a seamless interface for external
wall adapters or other auxiliary power options. The I
pin provides the option to remove the high current limit,
I
resistor, precision UVLO, thermal overload protection and
is available in a thermally-enhanced 32-lead 7mm × 4mm
DFN package for superior high current performance.
RJ45
LIMIT_HIGH
1
2
3
6
4
5
7
8
Rx1
Tx1
Rx2
Tx2
. The LTC4268-1 includes an onboard signature
DF1501S
DF1501S
0.1μF
0.1μF
SMAJ58A
SMAJ58A
PD
LTC4268-1
LTC4268-1
TYP APP
TYP APP
–
+
LIM_EN
42681fa
+
–
42681 F01b
V
OUT
+
–