LTC4269CDKD-1#PBF Linear Technology, LTC4269CDKD-1#PBF Datasheet - Page 12

IC PD/OPTO FLYBACK CTRLR 32-DFN

LTC4269CDKD-1#PBF

Manufacturer Part Number
LTC4269CDKD-1#PBF
Description
IC PD/OPTO FLYBACK CTRLR 32-DFN
Manufacturer
Linear Technology
Type
Power Over Ethernet (PoE)r
Datasheet

Specifications of LTC4269CDKD-1#PBF

Applications
Power Interface Switch for Power Over Ethernet (PoE) Devices
Voltage - Supply
14 V ~ 16 V
Operating Temperature
0°C ~ 70°C
Mounting Type
Surface Mount
Package / Case
32-DFN
Current - Supply
1.35mA
Interface
IEEE 802.3af
Controller Type
Powered Device Interface Controller (PD)
Input Voltage
60V
Supply Current
6.4mA
Digital Ic Case Style
DFN
No. Of Pins
32
Duty Cycle (%)
88%
Frequency
100kHz
Operating Temperature Range
0°C To +70°C
Msl
MSL 1 - Unlimited
Rohs Compliant
Yes
Operating Temperature (max)
70C
Operating Temperature (min)
0C
Pin Count
32
Mounting
Surface Mount
Package Type
DFN EP
Case Length
7mm
Screening Level
Commercial
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
APPLICATIONS INFORMATION
LTC4269-1
OVERVIEW
Power over Ethernet (PoE) continues to gain popularity
as more products are taking advantage of having DC
power and high speed data available from a single RJ45
connector. As PoE continues to grow in the marketplace,
Powered Device (PD) equipment vendors are running into
the 12.95W power limit established by the IEEE 802.3af
standard.
The IEE802.3at standard establishes a higher power
allocation for Power over Ethernet while maintaining
backwards compatibility with the existing IEEE 802.3af
systems. Power sourcing equipment (PSE) and powered
devices are distinguished as Type 1 complying with the
IEEE 802.3af/IEEE 802.3at power levels, or Type 2 com-
plying with the IEEE 802.3at power levels. The maximum
available power of a Type 2 PD is 25.5W.
The IEEE 802.3at standard also establishes a new method
of acquiring power classifi cation from a PD and communi-
cating the presence of a Type 2 PSE. A Type 2 PSE has the
option of acquiring PD power classifi cation by performing
2-event classifi cation (layer 1) or by communicating with
the PD over the data line (layer 2). In turn, a Type 2 PD
must be able to recognize both layers of communications
and identify a Type 2 PSE.
The LTC4269-1 is specifi cally designed to support the
front end of a PD that must operate under the IEEE 802.3at
standard. In particular, the LTC4269-1 provides the T2P
indicator bit which recognizes 2-event classifi cation.
This indicator bit may be used to alert the LTC4269-1
output load that a Type 2 PSE is present. With an internal
signature resistor, classifi cation circuitry, inrush control,
and thermal shutdown, the LTC4269-1 is a complete PD
Interface solution capable of supporting in the next gen-
eration PD applications.
MODES OF OPERATION
The LTC4269-1 has several modes of operation depend-
ing on the input voltage applied between the V
V
and current waveforms the LTC4269-1 may encounter with
the various modes of operation summarized in Table 1.
12
PORTN
pins. Figure 1 presents an illustration of voltage
PORTP
and
PSE
Figure 1. V
Current as a Function of Input Voltage
I
I
INRUSH = 100mA
I
1
CLASS
LOAD
R
–10
–20
–30
–40
–50
50
40
30
20
10
50
40
30
20
10
20
10
CLASS
=
I
IN
V1 – 2 DIODE DROPS
=
DEPENDENT ON R
V
R
PORTP
LOAD
NEG
dV
INRUSH
dt
OFF
DETECTION V1
25kΩ
R
V
=
TRACKS
POWER
PWRGD
POWER
V
CLASS
PORTN
, PWRGD, PWRGD and PD
INRUSH
PORTP
BAD
BAD
DETECTION V2
DETECTION I
DETECTION I
LTC4269-1
CLASSIFICATION
CLASSIFICATION
C1
PWRGD
PWRGD
V
ON
CLASS
PORTP
V
NEG
POWER
POWER
ON
GOOD
GOOD
I
2
1
2
=
SELECTION
V2 – 2 DIODE DROPS
PWRGD TRACKS
V
OFF
POWER
PORTN
25kΩ
LOAD, I
TRACKS
BAD
= R
PWRGD
POWER
V
PORTP
BAD
OFF
LOAD
TIME
TIME
TIME
TIME
TIME
R
IN DETECTION
RANGE
LOAD
LOAD
C1
C1
42691 F01
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