LTC4269-1 Datasheet, PDF (1/44 Pages) Linear Technology – IEEE 802.3at PD with Synchronous No-Opto Flyback Controller

FEATURES
n _{25.5W IEEE 802.3at Compliant (Type 2) PD}
n _{Integrated State-of-the-Art Synchronous Flyback}
Controller
– Isolated Power Supply Efficiency >92%
– 88% Efficiency Including Diode Bridge and
Hot Swap™ FET
n _{Flexible Integrated Auxiliary Power Support}
n _{Superior EMI Performance}
n _{Robust 100V 0.7Ω (Typ) Integrated Hot Swap MOSFET}
n _{IEEE 802.3at High Power Available Indicator}
n _{Integrated Signature Resistor and Programmable}
Class Current
n _{Undervoltage, Overvoltage and Thermal Protection}
n _{Short-Circuit Protection with Auto-Restart}
n _{Programmable Soft-Start and Switching Frequency}
n _{Complementary Power Good Indicators}
n _{Thermally Enhanced 7mm × 4mm DFN Package}
APPLICATIONS
n _{VoIP Phones with Advanced Display Options}
n _{Dual-Radio Wireless Access Points}
n _{PTZ Security Cameras}
n _{RFID Readers}
n _{Industrial Controls}
LTC4269-1
IEEE 802.3at PD with
Synchronous No-Opto
Flyback Controller
DESCRIPTION
The LTC^®4269-1 is an integrated Powered Device (PD)
controller and switching regulator intended for high
power IEEE 802.3at and 802.3af applications. The
LTC4269-1 is targeted for high efficiency, single and
multioutput applications from 10W to 25W. By support-
ing both 1-event and 2-event classifications, as defined
by the IEEE, the LTC4269-1 can be used in a wide range
of product configurations.
The LTC4269-1 synchronous, current mode, flyback con-
troller generates multiple supply rails in a single conversion
step providing for the highest system efficiency while main-
taining tight regulation across all outputs. The LTC4269-1
includes Linear Technology’s patented No-Opto feedback
topology to provide full IEEE 802.3 isolation without the
need of an opto-isolator circuit. A true soft-start function
allows graceful ramp-up of all output voltages.
All Linear Technology PD solutions include a shutdown
pin to provide flexible auxiliary power options. The
LTC4269-1 can accommodate adaptor voltages from 18V
to 60V and supports both PoE or aux dominance options.
The LTC4269-1 is available in a space saving 32-pin DFN
package.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. Hot Swap is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents, including
5841643.
TYPICAL APPLICATION
25W High Efficiency PD Solution
54V FROM ~ +
DATA PAIR _{~ –}
+
383k
10μH
10μF
2.2μF
27.4k
TO MICRO
14k
CONTROLLER ^3.01k
V_IN
39k
10μF
•
••
0.18μH
47μF +
5V
5A
100μF
54V FROM ^{~ +}
SPARE PAIR _{~ –}
0.1μF
30.9Ω
PWRGD UVLO T2P
V_PORTP
FB
V_CC PG SENSE⁺
R_CLASS
SHDN
V_PORTN
V_NEG SYNC GND OSC
LTC4269-1
PGDLY t_ON
SENSE^–
ENDLY
R_CMP
SG
V_CMP
C_CMP
12k
33pF
100k 38.3k 1.21k
0.1μF
33mΩ
10nF
1μF
2.2nF
••
42691 TA01a
42691fb
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