Power Supply Confusion

If it is a regulated supply there is no problem the voltage will remain at 5 volts and load will only take as much current as it needs. Most 5V supplies are regulated and the 2A supply should be ok.

If the supply is not regulated then the voltage may rise when the load less than expected.

It's like taking a drink out of a 55-gallon drum. The 5 volts is there, and the device takes what current it needs.

John

Because it is a voltage source, not a current source. The 2 A means that is the maximum safe current.; that is, fuses won't blow and transistors won't melt.

The 2 Amps is the available current (supply), which must be greater than the required load (0.5A). The load will only take the current it needs, but you need to have the current available to do so! The voltage however, must be within the required limits.

You just have to be careful where you spill that extra current ;-)

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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The 2A rating of the power supply tells what it is _capable_ of supplying, as a maximum. In general, a "DC power supply" puts out a contant voltage, (within limits) from its rated current down to no load at all.

The load, (the device that's powered) however, will, at the rated voltage, draw only what current it requires.

Look at your wall socket - in the US, it's capable of providing up to

15 amps of current, but a lamp of, for example, 120 watts rating, will only draw 1 amp from the socket.

Do a google search on "basic electricity tutorial" and "basic electronics tutorial" and "ohm's law" and stuff like that.

Good Luck! Rich

Thank you all....now if I want to operate another load which requires

5 V @ 2A....how we know how much this power supply can withstand....also what would be load on the AC...

Thank you all....now if I want to operate another load (in addition)which requires 5 V @ 2A....how we know how much this power supply can withstand....also what would be load on the AC...in

Watts out plus losses is watts in. So your 5 volt 2 amp load (10 watts) must consume at least 10 watts from the AC power lines. A very conservative estimate of efficiency is 50%, so assume about 20 watts drawn from the AC lines.

As they say in the NE here, 'You have Niagra Falls behind you.'

Cheers

So now you have two loads: one which draws .5 amps at

5 volts, and the other, which draws 2 amps at 5 volts. The total current of those two loads is 2.5 amps. That will overload your 2 amp supply. It is possible that the supply was very conservatively rated and can handle a 25% overload - but don't bank on it.

Ed