Power to Arduino: 5.2 VDC to USB port or +5V pin

Development Tools IDE 1.x
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Hi all,

I've gotten a ton of information from this forum, thank you. I know enough now to maybe be of help to others, so I joined.

And I have a question about supplying power to Arduino units. Briefly: is there any reason that the 5.2 to 5.6 VDC that USB chargers (AC-DC adapters outputting, typically, nominal 5.2 VDC) supply should be problematic to the Atmega controllers on these boards? I understand that chargers typically output >5 VDC whereas nominal 5V supplies do output 5.0 VDC.

I have searched and do understand that many people use chargers to power their Arduinos. I have done it and noticed no problems. I believe from specs and anecdotes that the voltage-range tolerance of controllers on these boards is ~3-5.5 VDC. My applications mean to be long-term datalogging. I want stuff to be real stable, this is why I'm asking.

What I'm interested in hearing is if someone has noteworthy experience (particularly, bad experience) with powering Arduinos at >5VDC through the units' power supply route that bypasses regulation (either to +5V pin or to USB in, which I do understand differ for the former's not having fuse or polarity protection). If not, that's swell too, and I'll be happy to know stuff ought to be fine.

Thanks!

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Muleface:
Hi all,

I've gotten a ton of information from this forum, thank you. I know enough now to maybe be of help to others, so I joined.

And I have a question about supplying power to Arduino units. Briefly: is there any reason that the 5.2 to 5.6 VDC that USB chargers (AC-DC adapters outputting, typically, nominal 5.2 VDC) supply should be problematic to the Atmega controllers on these boards? I understand that chargers typically output >5 VDC whereas nominal 5V supplies do output 5.0 VDC.

You mean power Arduino through Usb ?Your computer Usb port supplies Arduino With 5V DC and 500mAh.. Why should it damage the ATmega ?
5V.This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V).
ATmega's operating voltage is 1.8-5.5 volts.http://www.atmel.com/devices/atmega328.aspx
Also you should know that the power limits of arduino are 6V-20V.

I have searched and do understand that many people use chargers to power their Arduinos. I have done it and noticed no problems. I believe from specs and anecdotes that the voltage-range tolerance of controllers on these boards is ~3-5.5 VDC. My applications mean to be long-term datalogging. I want stuff to be real stable, this is why I'm asking.

It's important to use good quality chargers..
The recommended supply voltage is 7V-12V. I would suggets you buy a 7V charger.

What I'm interested in hearing is if someone has noteworthy experience (particularly, bad experience) with powering Arduinos at >5VDC through the units' power supply route that bypasses regulation (either to +5V pin or to USB in, which I do understand differ for the former's not having fuse or polarity protection). If not, that's swell too, and I'll be happy to know stuff ought to be fine.

No >5V it's not a problem as long it is between the limits..(6V-20V)..
You supply voltage to arduino either from Usb, Barrel jack ,or Vin..
note this : Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.

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Thanks zaxarias.

zaxarias:
You mean power Arduino through Usb ?Your computer Usb port supplies Arduino With 5V DC and 500mAh.. Why should it damage the ATmega ?

Spec for USB power is 5.0 +/- 5% VDC, and I've encountered ports that output something slightly different from 5.0 V. You ask why 5.0 VDC would damage ATmega -- right, I sure hope it wouldn't make any problem at all. I was wondering about > 5 VDC, which is very common among chargers (the spec for which also calls for an upper limit of 5 A).

ATmega's operating voltage is 1.8-5.5 volts.http://www.atmel.com/devices/atmega328.aspx
Also you should know that the power limits of arduino are 6V-20V.

Thanks for that link. I'd heard 5.5 V before but not from the horse's mouth.

It's important to use good quality chargers..
The recommended supply voltage is 7V-12V. I would suggets you buy a 7V charger.

Here's my issue. I mean to supply regulated 5.0 VDC (or slightly > 5.0 VDC depending on what people have to say) to the USB port. Arduino says USB port should receive 5.0 VDC. USB spec calls for a range up to 5.25 VDC. Is a charger outputting nominally 5.2 VDC OK? Does that mean the charger outputs 5.2 +/- 5% so that it may exceed ATmega specs? Has anyone damaged an ATmega using a USB charger to power Arduino through the USB port?

My understanding from the schematic is that sending power through an Arduino's USB port means it goes through a fuse, a polarity protection diode, and the voltage ripple smoothing capacitors. That seems better to me than sending power in through the +5V pin as some people report doing with success, but Arduino doesn't recommend.

I assume you don't mean to tell me I should put +7 VDC in through the USB port; I figure you mean 7V is good for the barrel power input or the Vin, which goes through the regulator.

So maybe that clarifies my question: +5.2 VDC in through the USB port long term -- is that OK? In this setting would a slight voltage spike above 5.5V damage the ATmega?

I should say, my concern derives largely from negative experiences with other computer parts' sensitivity to voltage. If half a volt is just not a problem to Arduinos, I'll quit thinking about it.

Thanks again for your time.