roines reenig wrote:
> I bought this fancy thermal massager thing that has a
> switching power supply. The interesting thing about
> the power supply (wall wart) is that it says input
> 100-240V AC at 50/60Hz 600mA and output 5.1V DC
> 2000mA. I've never noticed before this that power
> supplies state an input current requirement, assuming
> that the 600mA is the minimum input current
> requirement. Just curious, what are they doing in
> there to take a 600mA current and drive it up to a
> 2000mA? Is it just a capacitor? Is it normal?

It's a switching power supply, so in theory power out = power in, instead of
current out = current in as with a linear supply.  Switching power supplies
therefore have higher current out than in when the output voltage is lower
than the input voltage.

However, 600mA even at the lowest input voltage of 100V is still 60W, and
the output power is only 10.2W.  I seriously doubt this thing dissipates 50W
under these conditions, so maybe 600mA is an inrush spec, being rediculously
over conservative, a typo?


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