5V 2A switching power supply vs 5V 2.4A or even 3A what's the difference?

I was going to order a replacement Micro USB power supply, then I noticed there were several amperages to choose from. So what is the difference? How will this effect my electronics? What should I be concerned of in order to make the right choice?

Thanks in advance

hey guys i have a little problem i have a LM7505 for regulate 5v 1A but i need 5v 500mA any have any sugestion?

PD:sorry for my english only know the basic

marine_hm: I was going to order a replacement Micro USB power supply, then I noticed there were several amperages to choose from. So what is the difference? How will this effect my electronics? What should I be concerned of in order to make the right choice?

Depends what you're going to do with it. If you are going to power e.g a Nano, then it's pointless to buy a supply over 500mA. Because the onboard diode between USB and 5volt is limited to 500mA. Leo..

well budy marine_hm i dont tink wat your circuit be in fire but you have the resistor final of circuit? is important for the law of ohm your circuit can be hot for the low resistor and the wats of your circuit

2 different questions in the same thread. Sigh - start new thread for new question.
For the LM7505 question: In this case, never heard of a LM7505 - I assume you mean LM7805 which is a 5v 1A regulator. Your circuit will draw what it needs as long as your regulator/supply can deliver at least that much.

As for the “micro usb supply”, same sort of answer - as long as the supply is rated for at least what you need current wise, you should be OK. My preference is to use a somewhat larger supply than needed to allow it to run cooler. You do need to make sure exactly what type of supply it is - some of the 5v supplies are not regulated and will actually have 7 or 8 volts on the output no load, while others are regulated and will be 5v as long as you do not exceed their ratings.

no is for the arduino nano only is for charge my telephone i gona make a charge for telephone whit bateries AA and i need protect my telephone whit 500mA, no 1A but whit 1A is worging Re: 5V 500mA problem

zaidro: hey guys i have a little problem i have a LM7505 for regulate 5v 1A but i need 5v 500mA any have any sugestion?

Not nice to hijack someone elses thread. Quick answer: The 7805 [u]can[/u] deliver up to about 1Amp (if the input voltage is over 7volt and the device is properly heatsinked). That does not mean you [u]have[/u] to draw 1Amp. The [u]load[/u] will draw whatever it needs. No problem if the load (Arduino, LEDs, etc.) draws only 100mA or 500mA. Leo..

Wawa: Not nice to hijack someone elses thread. Quick answer: The 7805 [u]can[/u] deliver up to about 1Amp (if the input voltage is over 7volt and the device is properly heatsinked). That does not mean you [u]have[/u] to draw 1Amp. The [u]load[/u] will draw whatever it needs. No problem if the load (Arduino, LEDs, etc.) draws only 100mA or 500mA. Leo..

so you say wath the 5v 1A is standar for the values of charging any batery of telephone?

zaidro:
i gona make a charge for telephone whit bateries AA

and i need protect my telephone whit 500mA, no 1A but whit 1A is worging Re: 5V 500mA problem

You might need the full charge of three AA batteries to charge the cellphone only once.
The 7805 is very inefficient. Better use a micro-power boost converter.

No need to protect a cellphone from current.
Just connect a 5volt supply. The charge controller inside the cellphone knows what to do and when to stop.
Leo…

Wawa: You might need the full charge of three AA batteries to charge the cellphone only once. The 7805 is very inefficient. Better use a micro-power boost converter.

No need to protect a cellphone from current. Just connect a 5volt supply. The charge controller inside the cellphone knows what to do and when to stop. Leo..

i use a booster amplifier from the boltage is a LM2577 step up. so only need use the 4 bateries AA and the booster?

gpsmikey: As for the "micro usb supply", same sort of answer - as long as the supply is rated for at least what you need current wise, you should be OK. My preference is to use a somewhat larger supply than needed to allow it to run cooler. You do need to make sure exactly what type of supply it is - some of the 5v supplies are not regulated and will actually have 7 or 8 volts on the output no load, while others are regulated and will be 5v as long as you do not exceed their ratings.

That's what I was thinking but not my expertise. Switching means it comes up to 5V and then switches on to avoid overcurrent?

marine_hm: That's what I was thinking but not my expertise. Switching means it comes up to 5V and then switches on to avoid overcurrent?

No - a switching type regulator takes a higher voltage and chops it basically so that the output is a constant voltage (not quite that simple but along those lines). A switching regulator is more efficient than a linear regulator because it is switching between on and off instead of in the linear region. Look up "switching regulator" for more details. They can work in both boost or buck mode (boost gives you a higher output than the input and buck gives you a lower output than the input. Either way, they are smaller and more efficient than a linear regulator (like using a LM7805 for example).

But, I would be safe using a 5V 2.4A for most electronic devices that use the micro USB?

Thanks Paul. I will look for that.

zaidro: so only need use the 4 bateries AA and the booster?

You can use a boost converter as long as the input voltage is lower than the output voltage.

Six AA batteries and a buck (stepdown) converter also works.

Make sure that the output is 5volt before you connect it to your phone. Leo..

marine_hm: But, I would be safe using a 5V 2.4A for most electronic devices that use the micro USB?

You could use a 5V 100A for such devices. The Amp rating only means current available. Devices only draw what they need. As long as you have enough, you're fine. You can't really have 'too much' for amps from a power supply. I think you're missing this point. You need to know it. Remember it.

Think of it this way. If you have a 5v device that draws 0.5Amps (that's 500mA) while it is being used. You can power it with a 5v 0.5A power source.

If you have two such identical devices, they each draw 0.5A, meaning you need at least a 5v 1A (that's 1000mA) power source. But you can turn one of them off or unplug it, and the other one will still only be drawing its 0.5A. It doesn't suddenly use more power just because more is available.

Amperage ratings tell you how much you could draw. Not how much you must use up exactly else something is going to get force fed and explode. (That would be voltage.)

marine_hm:
But, I would be safe using a 5V 2.4A for most electronic devices that use the micro USB?

Yes. Nearly 2 and a half amps will run nearly any commercial device.

If it’s a device you made yourself, test it with an ammeter before unleashing it on the world. You should understand your project well enough to predict the current draw to a couple tens of milliamps, or a few microamps for a low-power device .

As multiple people here have correctly pointed out, the amp rating is a MAXIMUM rating, just the 5V is a "fixed" property of the supply. So in theory, you can use a 5V 500mA supply just as well as a 5V 1000A supply to supply your project with 250mA.

If you exceed the rating, in the best case, the supply will shut off, in a slightly worse case, the voltage will drop (resulting in unexpected behavior), in the worst case, it will get hot and catch fire.

In some conditions, it might be interesting to look at the efficiency and the quiescent current. I have seen phone chargers that draw 2W to power an ESP8366 of 0.5W. This might not be important for playing around, but if you have 20 devices lying around always on for home automation, than it gets interesting. A current rating that is closer to the actual demand has the tendency to have better efficiency, but in the phone charger range, there is also a good bunch of quality involved.