[Commotion-dev] TP-Link WDR4300 with more than 12V power supply

[Andy Gunn]

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Hey Ben - thanks for responding, I agree with pretty much everything
you said. Using anything too far off from the power supply that ships
with a unit can definitely cause issues with the internal components.

What I'm trying to find out is how far off is too far off? I think 15
volts is probably okay, and wouldn't cause significant overheating of
the components in the WDR4300, since the specifications on those
appeared to be rated to 18V minimum, in some cases up to 30 volts. So,
I'm guessing that the lifespan of the unit won't be significantly
affected by 15 volts. Higher than that? Maybe.

Of course, there is no guarantee all TP-Link units ship with the same
regulators, so many routers might be different. Even another 4300 unit
made at a different time with different components might freak out or
burn out at anything above 15 volts.

In a very high heat environment though, all bets are off - in which
case, stick to the rated voltages! And maybe get routers that are
outdoor rated, as they can usually tolerate higher temperatures.


On 04/14/2015 02:44 PM, Ben West wrote:
> The regulator circuits on the TP-Link that develop the 5V, 3.3V,
> and whatever other logic supply voltages from the bulk 12V will
> usually have rated tolerances of up to 2x the stated input (e.g.
> 24V).  However, the reason for designing in these tolerances is to
> ensure a reasonable life span for the power regulator's
> electronics, and also to elegantly tolerate variation on the actual
> output of the mass-produced 12V wall-warts (which may range 9V to
> 15V).
> 
> Subjecting the unit to substantially greater than 12V will shorten
> its life, and it may even lead to overheating in situations where
> ambient temp is high (e.g. an enclosure w/o ventilation).  Similar
> for powering it with substantially less than 12V, as the DC-DC on
> the TP-Link will then have to draw more current to supply the
> onboard voltage rails, possibly exceeding component ratings.
> (Which is when the magic smoke appears.)
> 
> In addition, the 15V supplies you're trying out will themselves
> have variation on their output.  Some may put out 18V or 20V and
> fry a unit. A way of capping that output to 15V would be good.
> 

- -- 
Andy Gunn, Field Engineer
Open Technology Institute, New America
andygunn at opentechinstitute.org | 202-596-3484
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