[MLB-WIRELESS] PoE

[Robert Hart]

Tyson Clugg wrote:
>> There is a switchmode power supply installed on the roof not detailed in 
>> the images for 12V and 5V in the case we want it add ip camera at some 
>> stage.
>>
>> http://www.air-stream.org.au/LM2576
>>
>> And all done on one cat5e cable run :-)
>>     
>
> With 12V input, the LM2576 runs at around 75% efficiency giving about
> 3.5W of unwanted heat in a weatherproof enclosure.  Is there a more
> efficient IC for the job?
>   
There are many SMR IC's out there best would be ~90%, but generally more 
expensive, or require more external components or are less available.

Nevertheless, I have yet to put a heat sink on these guys as they only 
run warm to touch  powering more routers requiring 2Amps.

But adding a small TO220 12`C/W would more than cope if you ran them at 
full rating, quite safe too as they have thremal overload and short 
circuit protection.

We have three of these on our network powering R100 routers one of these 
has a SR2 400mW card installed and have been running for a year now 
without a hitch.

But I guest the main point is PoE is very easy to deploy even if your 
stuck with a 5V router

Robert
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