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LTC4268IDKD-1#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P46
42681fc
LTC4268-1
1
High Power PD With
Synchronous No-Opto
Flyback Controller
The LT C
®
4268-1 is an integrated Powered Device (PD)
controller and switching regulator intended for IEEE 802.3af
and high power PoE applications up to 35W. By including
a precision dual current limit, the LTC4268-1 keeps inrush
below IEEE 802.3af current limit levels to ensure interop-
erability success while enabling high power applications
with a 750mA operational current limit.
The LTC4268-1 synchronous, current-mode, flyback
controller generates multiple supply rails in a single
conversion providing for the highest system efficiency
while maintaining tight regulation across all outputs. The
LTC4268-1 includes Linear Technology’s patented No-Opto
feedback topology to provide full IEEE 802.3af isolation
without the need of opto-isolator circuitry.
The oversized power path and high performance flyback
controller of the LTC4268-1 combine to make the ultimate
solution for power hungry PoE applications such as WAPs,
PTZ security cameras, RFID readers and ultra-efficient
802.3af applications running near the 12.95W limit.
The LTC4268-1 is available in a space saving 32-pin DFN
package.
n
Robust 35W PD Front End
n
IEEE 802.3af Compliant
n
Rugged 750mA Power MOSFET With Precision Dual
Level Current Limit
n
High Performance Synchronous Flyback Controller
n
IEEE Isolation Obtained Without an Opto-Isolator
n
Adjustable Frequency from 50kHz to 250kHz
n
Tight Multi-Output Regulation With Load
Compensation
n
Onboard 25k Signature Resistor
n
Programmable Classification Current to 75mA
n
Complete Thermal and Over-Current Protection
n
Available in Compact 32-Pin 7mm × 4mm DFN
Package
n
VoIP Phones With Advanced Display Options
n
Dual-Radio Wireless Access Points
n
PTZ Security Cameras
n
RFID Readers
n
Industrial Controls
n
Magnetic Card Readers
n
High Power PoE Systems
35W High Efficiency PD Solution
169k
R
CLASS
3.01k
1%
28.7k
1%
20Ω
47Ω
47k
100k
BAS21
56Ω
•
•
•
•
100pF≥5µF
470µF
×4
3.3V
–54V FROM
DATA PAIR
–54V FROM
SPARE PAIR
T1
0.02Ω
47µF
SMAJ58A
T1: PA1477NL
T2: PA0184
DF1501S
DF1501S
0.1µF
100k
20k
10k
15Ω
330Ω
47pF
0.033µF
10nF
2.2nF
T2
0.1µF
42681 TA01a
1µF
BAT54
t
ON
12k
PGDLYV
NEG
SYNC
R
CLASS
V
PORTN
SHDN
SENSE
–
V
CMP
SENSE
+
R
CMP
ENDLY OSC
LTC4268-1
GND SFST
SG
Si7336ADP
B0540W
Si4490DY
FMMT618
FMMT718
V
CC
I
LIM_EN
UVLOPWRGDPWRGDV
PORTP
T1
•
PGFB
C
CMP
+
–
~
~
+
–
~
~
+
+
Typical applicaTion
DescripTion
FeaTures
applicaTions
L, LT , LT C, LT M and SwitcherCAD are registered trademarks and LTPoE
++
and ThinSOT are
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners. Protected by U.S. Patents including 5841643.
LTC4268-1
2
42681fc
pin conFiguraTionabsoluTe MaxiMuM raTings
V
PORTN
Voltage .......................................... 0.3V to –90V
V
NEG
Voltage ..................V
PORTN
+ 90V to V
PORTN
–0.3V
V
CC
to GND Voltage (Note 3)
Low Impedance Source ......................... –0.3V to 18V
Current Fed ..........................................30mA into V
CC
R
CLASS
, I
LIM_EN
Voltage .. V
PORTN
+ 7V to V
PORTN
– 0.3V
SHDN Voltage ...............V
PORTN
+ 90V to V
PORTN
– 0.3V
PWRGD Voltage (Note 3)
Low Impedance Source .... V
NEG
+ 11V to V
NEG
– 0.3V
Current Fed ..........................................................5mA
PWRGD Voltage ............ V
PORTN
+ 80V to V
PORTN
– 0.3V
PWRGD Current .....................................................10mA
R
CLASS
Current ....................................................100mA
SENSE
–
, SENSE
+
Voltage ........................ –0.5V to +0.5V
UVLO, SYNC Voltage ...................................–0.3V to V
CC
FB Current ..............................................................±2mA
V
CMP
Current ......................................................... ±1mA
Operating Ambient Temperature Range (Notes 4, 5)
LTC4268-1C ............................................. 0°C to 70°C
LTC4268-1I ..........................................–40°C to 85°C
Junction Temperature (Note 5) ............................. 150°C
Storage Temperature Range .................. –65°C to 150°C
(Notes 1, 2)
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
33
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
V
PORTP
NC
PWRGD
PWRGD
V
NEG
V
NEG
V
NEG
NC
PG
PGDLY
R
CMP
C
CMP
SENSE+
SENSE–
UVLO
V
CMP
SHDN
NC
R
CLASS
I
LIM_EN
V
PORTN
V
PORTN
V
PORTN
NC
SG
V
CC
t
ON
ENDLY
SYNC
SFST
OSC
FB
TOP VIEW
DKD32 PACKAGE
32-LEAD (7mm × 4mm) PLASTIC DFN
T
JMAX
= 150°C,θ
JA
= 49°C/W, θ
JC
= 4.7°C/W
EXPOSED PAD (PIN 33) MUST BE SOLDERED TO
HEAT SINKING PLANE THAT IS ELECTRICALLY CONNECTED TO GND
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC4268CDKD-1#PBF
LTC4268IDKD-1#PBF
LTC4268CDKD-1#TRPBF
LTC4268IDKD-1#TRPBF
42681
42681
32-Lead (7mm × 4mm) Plastic DFN
32-Lead (7mm × 4mm) Plastic DFN
0°C to 70°C
–40°C to 85°C
LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC4268CDKD-1
LTC4268IDKD-1
LTC4268CDKD-1#TR
LTC4268IDKD-1#TR
42681
42681
32-Lead (7mm × 4mm) Plastic DFN
32-Lead (7mm × 4mm) Plastic DFN
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
orDer inForMaTion
42681fc
LTC4268-1
3
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 14V, SG open, V
CMP
= 1.5V, V
SENSE
= 0V, R
CMP
= 1k, R
tON
= 90k,
R
PGDLY
= 27.4k, R
ENDLY
= 90k, unless otherwise specified.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
PORT
Supply Voltage
IEEE 802.3af System
Signature Range
Classification Range
UVLO Turn-On Voltage
UVLO Turn-Off Voltage
Voltage With Respect to V
PORTP
Pin
(Notes 6, 7, 8, 9, 10)
l
l
l
l
l
–1.5
–12.5
–37.7
–29.8
–38.9
–30.6
–57
–10.1
–21
–40.2
–31.5
V
V
V
V
V
V
TURNON
V
CC
Turn-On Voltage Voltage With Respect to GND
l
14 15.3 16.6 V
V
TURNOFF
V
CC
Turn-Off Voltage Voltage With Respect to GND
l
8 9.7 11 V
V
HYST
V
CC
Hysteresis V
TURNON
– V
TURNOFF
l
4 5.6 7.2 V
V
CLAMP
V
CC
Shunt Regulator Voltage I
VCC
= 15mA, V
UVLO
= 0V, Voltage With
Respect to GND
l
19.5 20.2 V
I
VCC
V
CC
Supply Current V
CMP
= Open (Note 11)
l
4 6.4 10 mA
I
VCC_START
V
CC
Start-Up Current V
CC
= 10V
l
180 400 µA
V
FB
Feedback Regulation Voltage
l
1.22 1.237 1.251 V
I
FB_BIAS
Feedback Pin Input Bias Current R
CMP
Open 200 nA
g
m
Feedback Amplifier
Transconductance
l
700 1000 1400 A/V
I
FB
Feedback Amplifier Source or Sink
Current
l
25 55 90 µA
V
FBCLAMP
Feedback Amplifier Clamp Voltage V
FB
= 0.9V
V
FB
= 1.4V
2.56
0.84
V
V
%V
REF
Reference Voltage Line Regulation 12V ≤ V
CC
≤ 18V
l
0.005 0.02 %/V
A
V
Feedback Amplifier Voltage Gain V
CMP
= 1.2V to 1.7V 1500 V/V
I
SFST
Soft-Start Charging Current V
SFST
= 1.5V 16 20 25 µA
I
SFST
Soft-Start Discharge Current V
SFST
= 1.5V, V
UVLO
= 0V 0.8 1.3 mA
V
CMP_THLD
Control Pin Threshold (VCMP) Duty Cycle = Min 1 V
V
PG_HIGH
,
V
SG_HIGH
PG, SG, Output High Level
l
6.6 7.4 8 V
V
PG_LOW
,
V
SG_LOW
PG, SG, Output Low Level
l
0.01 0.05 V
V
PG_SHDN
,
V
SG_SHDN
PG, SG, Output Shutdown Strength V
UVLO
= 0V; I
PG
, I
SG
= 20mA
l
1.4 2.3 V
t
PG_RISE
,
t
SG_RISE
PG, SG Rise Time C
PG
, C
SG
= 1nF 15 ns
t
PG_FALL
,
t
SG_FALL
PG, SG Fall Time C
PG
, C
SG
= 1nF 15 ns
V
SENSE_LIM
Switch Current Threshold at Maximum
V
CMP
Measured at V
SENSE+
l
88 100 110 mV
DV
SENSE
/DV
CMP
Sense Threshold vs V
CMP
0.07 V/V
V
SENSE_OC
Sense Pin Overcurrent Fault Voltage V
SENSE+
, V
SFST
< 1V
l
205 230 mV
V
IH_SHDN
Shutdown High Level Input Voltage With Respect to V
PORTN
High Level = Shutdown (Note 12)
l
3 57 V
V
IL_SHDN
Shutdown Low Level Input Voltage With Respect to V
PORTN
l
0.45 V
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P46

LTC4268IDKD-1#TRPBF

Mfr. #:
Buy LTC4268IDKD-1#TRPBF
Manufacturer:
Analog Devices Inc.
Description:
Power Switch ICs - POE / LAN EEE 802.3af High Power PD with Synchronous NoOpto Flyback Controller
Lifecycle:
New from this manufacturer.
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