LTC4265 Datasheet, PDF (1/20 Pages) Linear Technology – IEEE 802.3at High Power PD Interface Controller with 2-Event Classifi cation Recognition

LTC4265
IEEE 802.3at High Power PD
Interface Controller with
2-Event Classification Recognition
FEATURES
n _{IEEE 802.3af/at Powered Device (PD) Controller}
n _{IEEE 802.3at 2-event Classification Signaling}
n _{Programmable Classification Current}
n _{Flexible Auxiliary Power Support Using SHDN Pin}
n _{Rugged 100V Onboard MOSFET with 100mA Inrush}
Current Limit.
n _{Complementary Power Good Outputs}
n _{Onboard Signature Resistor}
n _{Comprehensive Thermal Protection}
n _{Undervoltage and Overvoltage Lockout}
n _{12-Lead, 4mm × 3mm DFN Package}
APPLICATIONS
n _{802.11n Access Points}
n _{High Power VoIP Video Phones}
n _{RFID Reader Systems}
n _{PTZ Security Cameras and Surveillance Equipment}
DESCRIPTION
The LTC^®4265 is a 3rd generation Powered Device (PD)
Interface controller intended for IEEE 802.3at high power
Power-over-Ethernet (PoE) applications up to 25.5W. By
supporting 1-event and 2-event classification signaling as
defined by IEEE 802.3, the LTC4265 can be used in a wide
range of product configurations. A 100V MOSFET isolates
the DC/DC converter during detection and classification,
and provides 100mA inrush current for a smooth power-
up transition. The LTC4265 also includes complementary
power good outputs, an on-board signature resistor,
undervoltage/overvoltage lockout and comprehensive
thermal protection. All Linear Technology PD solutions
include a shutdown pin with signature corrupt to provide
flexible auxiliary power options.
The LTC4265 PD interface controller can be used along
with a variety of DC/DC converter products to provide a
complete, cost effective power solution for high power
PD applications.
The LTC4265 is available in the space-saving low profile
(4mm × 3mm) DFN package and is drop-in compatible
with the LTC4264.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
~+
54V FROM
0.1μF
DATA PAIR
~–
~+
54V FROM
SPARE PAIR _~
–
TO AUX
LTC4265
GND
R_CLASS PWRGD
R_CLASS
PWRGD
SHDN
V_IN
V_OUT
T2PSE
5μF ⁺
MIN
V⁺
SWITCHING
POWER
SUPPLY
RUN
RTN
+
3.3V
TO LOGIC
–
TO LOGIC
4265 TA01a
GND – V_IN
50V/DIV
GND – V_OUT
50V/DIV
PWRGD – V_OUT
50V/DIV
I_PD
100mA/DIV
Turn-On vs Time
C_LOAD = 100μF
TIME
25ms/DIV
4265 TA01b
4265f
1