Power Supply Info

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I don't know why but linksys looks like they like starving their Wireless Routers and AP's of POWER. They supply you with a .5 to 1.5 amp switching power supply way under what you need . Look a the product spec sheet for a WPC300N PCMCIA WiFi card;

Power Consumption TX: <900mA (Maximum) RX: <700mA (Maximum)

http://downloads.linksysbycisco.com/downloads/WPC300N_ds,0.pdf [broken]

Look at what the BCM4705 CPU Power Consumption is; 5v @ 2.4w = 0.48 amp just under 1/2 amp.

http://www.broadcom.com/collateral/pb/4705-PB01-R.pdf [broken]

the switch BCM 5325 Power Consumption is 5v 1.4W = 0.28 amp


also add the RAM power consumption (unknown at this time)

Remember the variation that is needed; normally 5% to 10%

Power needed just for this item at minimum so far: 900 ma 270 ma 480 ma total: 1650 ma which equals 1.65 amp

Other Routers have this problem too!!

This is a thread were you can find out More Info if you need: DD-Wrt Forum

Engineer's comment:
I'm not refuting the fact that they could very well be power starved, I just want to clear up a misconception of the original author.

What is important here is the sum of the POWERS not the sum of the currents. Switching power supplies, are very efficient at converting voltage/current levels; and if properly designed can reach efficiencies of 95%.

Using the values provided above, and assuming a Vbus of 3.3v:
1.65a * 3.3v = 5.45w

The router needs at least 5.45w to operate correctly.

Now let's look at the wall wort.
12v output, at 500ma = 6watts.
factoring in the inefficiencies of the power supply on the router, it is obvious that we are running at the limit of the wall wort.

Recommendation: if you have a 12v/500ma adapter with your router, seriously consider getting a new one. Get an adapter rated for at least 1a at 12v and you should be fine.

--Dejagerd 03:26, 19 February 2010 (CET)