Linear Technology DC1366A - LTC4266: 25.5W PoE+ 4-Port Midspan PSE (req. DC590) DC1366A DC1366A Scheda Tecnica

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1366A  

IEEE802.3AF/AT POWER-OVER-ETHERNET POWER SOURCING EQUIPMENT CONTROLLER 

LTC4266 

1

Demonstration circuit DC1366A features the 
LTC

®

4266CUHF, a quad network power controller with 

I

2

C™ interface, designed for use in IEEE 802.3at™-

compliant Power Sourcing Equipment (PSE).  Inte-
grated into a tiny 5mm

×7mm 38-pin QFN package are 

four independent ports controlling external N-channel 
power MOSFETs.  Each port features: 

■  Reliable 4-point PD detection 
■  Selectable 1 or 2-event classification 
■  Inrush current limiting 
■  Extremely fast short-circuit protection with 

programmable foldback current threshold 

■  Programmable cutoff current threshold for 

class power enforcement 

■  Voltage and current readback 
■  DC disconnect sensing 

The DC1366A board is configured like a midspan 
PSE with two RJ45 connectors for each port such 
that gigabit Ethernet data can pass through the 
board at full line rates while dc power is injected by 
the LTC4266 on the PD side of the board. 

Often one of the most challenging aspects of de-
signing a PSE system is the power management 
software; Linear Technology makes the job easier 
with the fully-featured LTC4266 register set and an 
advanced GUI software application.  The GUI allows 
the user full and easy access to the LTC4266 regis-
ter set with detailed contextual help info.  The GUI 
also includes a host computer emulator to demon-
strate basic power management techniques: the 
user selects various system parameters such as PSE 
type (endspan or midspan), 1 or 2-event classifica-
tion, total system power budget, and fault handling 
rules; then with the click of a button the host com-
puter emulator takes control of the system, manag-
ing the power budget as PDs are connected and dis-
connected, and logging all events. 

The DC1366A demo boards, CAD files, and GUI soft-
ware are available only under a non-disclosure 
agreement (NDA).  Contact your local Linear Tech-
nology sales person or field applications engineer. 

L, LT, LTC, and QuickEval are trademarks of Linear Technology 
Corporation; I2C is a trademark of Phillips Electronics N.V.; all other 
trademarks are the property of their respective owners. 

Figure 1 shows the basic setup.  The LTC4266 requires 
two power supply rails: V

DD

 (nominally 3.3V) and V

EE

 

(nominally -54V).  The V

DD

 supply can be provided by 

the DC590B board or an external bench supply. 

When running the GUI application on a Windows 
computer, the DC590B board from Linear Tech is 
used to interface a USB port on the PC to the I

2

C bus 

on the DC1366A board.  The DC590B also provides 
optoisolation of the I

2

C bus, and an isolated 3.3V 

supply to run the LTC4266 chip; the user need only 
provide the V

EE

 supply. 

Alternatively, the user can omit the DC590B and 
connect some other I

2

C master device to the 

DC1366A board.  If the DC590B is omitted then a 
bench power supply must provide V

DD

. 

For applications where power management is not 
required, the LTC4266 features an AUTO mode al-
lowing it to operate completely autonomously. 

Choose one of the setup procedures shown on the next 
page, depending on whether or not the GUI application 
software is required.