LTC4264 LINER [Linear Technology], LTC4264 Datasheet - Page 15

• Manufacturer Part Number: LTC4264
• Description: High Power PD Interface Controller with 750mA Current Limit
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
thermal shutdown. For DC loads the maximum ambient
temperature can be calculated as:
where T
ture, θ
(43°C/W), and PWR is the power dissipation for the
LTC4264 in Watts (I
EXTERNAL INTERFACE AND COMPONENT SELECTION
Transformer
Nodes on an Ethernet network commonly interface to
the outside world via an isolation transformer (Figure 9).
For powered devices, the isolation transformer must
include a center tap on the media (cable) side. Proper
termination is required around the transformer to provide
correct impedance matching and to avoid radiated and
conducted emissions. For high power applications beyond
IEEE 802.3af limits, the increased current levels increase
the current imbalance in the magnetics. This imbalance
reduces the perceived inductance and can interfere with
data transmission. Transformers specifi cally designed for
high current applications are required. Transformer vendors
T
MAX
JA
MAX
= 125 – θ
is the junction-to-ambient thermal resistance
is the maximum ambient operating tempera-
JA
PD
• PWR (°C)
RJ45
Figure 9. PD Front-End with Isolation Transformer, Diode Bridges, Capacitors and TVS
2
1
2
3
6
4
5
7
8
R
TX
TX
RX
RX
ON
+
–
+
–
SPARE
SPARE
).
+
–
PULSE H2019
16
15
14
11
10
9
T1
1
2
3
6
7
8
BR2
HD01
TO PHY
C14
0.1µF
100V
such as Bel Fuse, Coilcraft, Halo, Pulse, and Tyco (Table 4)
can provide assistance with selection of an appropriate
isolation transformer and proper termination methods.
These vendors have transformers specifi cally designed
for use in high power PD applications.
Table 4. Power over Ethernet Transformer Vendors
VENDOR
Bel Fuse Inc.
Coilcraft Inc.
Halo Electronics
Pulse Engineering
Tyco Electronics
SMAJ58A
BR1
HD01
TVS
D3
V
IN
LTC4264
V
GND
OUT
4264 F09
CONTACT INFORMATION
206 Van Vorst Street
Jersey City, NJ 07302
Tel: [phone]
www.belfuse.com
1102 Silver Lake Road
Gary, IL 60013
Tel: [phone]
www.coilcraft.com
1861 Landings Drive
Mountain View, CA 94043
Tel: [phone]
www.haloelectronics.com
12220 World Trade Drive
San Diego, CA 92128
Tel: [phone]
www.pulseeng.com
308 Constitution Drive
Menlo Park, CA 94025-1164
Tel: [phone]
www.circuitprotection.com
C1
V
OUT
LTC4264
15
4264f