LTC4264_15 Datasheet, PDF (1/24 Pages) Linear Technology – High Power PD Interface Controller with 750mA Current Limit

FEATURES
■ _{Complete High Power PD Interface Controller}
■ _{IEEE 802.3af}^® _Compliant
■ _{Onboard 750mA Power MOSFET}
■ _{Complementary Power Good Outputs}
■ _{Flexible Auxiliary Power Options}
■ _{Precision Dual Current Limit with Disable}
■ _{Programmable Classification Current to 75mA}
■ _{Onboard 25k Signature Resistor with Disable}
■ _{Undervoltage Lockout}
■ _{Complete Thermal Overload Protection}
■ _{Available in Low Profile (4mm × 3mm) DFN Package}
APPLICATIONS
■ _{802.11n Access Points}
■ _{High Power VoIP Video Phones}
■ _{RFID Reader Systems}
■ _{PTZ Security Cameras and Surveillance Equipment}
LTC4264
High Power PD Interface
Controller with 750mA
Current Limit
DESCRIPTION
The LTC^®4264 is an integrated Powered Device (PD) in-
terface controller intended for IEEE 802.3af Power over
Ethernet (PoE) and high power PoE applications up to 35W.
By including a precision dual current limit, the LTC4264
keeps inrush below the IEEE802.3af current limit levels
to ensure interoperability success while allowing for high
power PD operation. The LTC4264 includes a field-proven
power MOSFET delivering up to 750mA to the PD load while
maintaining compliance with the IEEE802.3af standard.
Complementary power good outputs allow the LTC4264 to
interface directly with a host of DC/DC converter products.
The LTC4264 provides a complete signature and power
interface solution for PD designs by incorporating the 25k
signature resistor, classification circuitry, input current
limit, undervoltage lockout, thermal overload protection,
signature disable and power good signaling.
The LTC4264 PD interface controller can be used along with
a variety of Linear Technology DC/DC converter products
to provide a complete, cost effective power solution for
high power PD applications.
The LTC4264 is available in the space-saving low profile
(4mm × 3mm) DFN package.
, 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
DATA PAIR
~+
DF1501S
~–
0.1µF
–54V FROM
SPARE PAIR
~+
DF1501S
~–
SMAJ58A
R_CLASS
LTC4264
SHDN
GND
R_CLASS PWRGD
PWRGD
I_{LIM_EN}
V_IN
V_OUT
5µF ⁺
MIN
V_IN
SWITCHING
POWER
SUPPLY
RUN
RTN
+
3.3V
TO LOGIC
–
4264 TA01a
V_IN
50V/DIV
V_OUT
50V/DIV
PWRGD – V_OUT
50V/DIV
I_IN
200mA/DIV
Turn On vs Time
C_LOAD = 100µF
TIME (5ms/DIV)
4264 TA01b
4264f
1