max volts

[forumisto]

Hello
I have a powet adaptor that gives 5.25 V and 1 A at output.
Is it too much volts?

[Alan Thew]

That should be just OK. It's borderline within 5 per cent of 5V so it's impossible to predict. Try it and see. It's not far enough over 5V that I would have thought you could do much damage: I tried a 2A PSU at 5.40V and the Pi wouldn't boot. I'm now using a 4A PSU from an old label printer at 5.15V and it runs like a good-un. (It's powering my Pi and my USB hub -- minor adaptations with a soldering iron -- and the higher current rating has put an end to all my previous problems of random freezes and keyboard repeats using a 1A phone charger.)

[Alan Thew]

Those voltages are unloaded, by the way, as I assume that's what you're measuring too. Some older/cheaper wallwart-type adaptors will be way over the rated voltage unloaded, but will drop when a current is drawn. They're best avoided. Most micro-USB phone chargers will stick pretty close to 5V; the problem is getting enough current.

[Larry_Adlard]

For a while (2/3 days) I ran the Pi at 5.35 volts from a battery supply that could supply as much as several devices could handle without suffering a drop in voltage.

I haven't done it for an extended period. The present supply maintains between 5.00v and 5.15v.

The point is 5.35v didn't damage the device. Device RG2 near the input looks like a voltage regulator to me. It seems to me that within reason, slightly over is better than inadequate.

It was anticipated that the Pi could be powered from a battery source. The only problem is the power connector, but we've discussed that to death, elsewhere.

[hippy]

The point is 5.35v didn't damage the device.

To be pedantic; 5.35v didn't appear to damage the device.

We do know that pushing 6V into the R-Pi "*will* shorten the life of the SoC" (http://www.raspberrypi.org/phpBB3/viewt ... f=2&t=5064) and may damage other things attached to it but it is hard to assess what damage is being done without officially stated recommended and absolute maximum ratings of the SoCs.

[Joe Schmoe]

We do know that pushing 6V into the R-Pi "*will* shorten the life of the SoC" (http://www.raspberrypi.org/phpBB3/viewt ... f=2&t=5064) and may damage other things attached to it but it is hard to assess what damage is being done without officially stated recommended and absolute maximum ratings of the SoCs.

I know that that has been stated as official policy (i.e., it came from Dom or Gert and/or someone else "official"), but I don't think that it is true, based on most recent information.

That is, the SoC doesn't ever see the total input voltage; the SoC, and the rest of the on-board electronics, other than the USB, only sees the output of the first voltage regulator, which drops the input voltage down to 3V3. So, as I read it, the only affect (on the SoC - and everything else, except the USB) that a high input voltage would have, is more heat being generated by the regulator.

But, what I have heard, is that excessive input voltage will result in excessive voltage being supplied to the USB ports, since they (the USB ports) *are* connected directly to the input voltage. So, as I understand it, that is the only real concern (from supplying excessive input voltage).

[AndrewS]

That is, the SoC doesn't ever see the total input voltage; the SoC, and the rest of the on-board electronics, other than the USB, only sees the output of the first voltage regulator, which drops the input voltage down to 3V3.

I'm afraid you're wrong http://elinux.org/RPi_BCM2835_Signals

[Joe Schmoe]

That is, the SoC doesn't ever see the total input voltage; the SoC, and the rest of the on-board electronics, other than the USB, only sees the output of the first voltage regulator, which drops the input voltage down to 3V3.

I'm afraid you're wrong http://elinux.org/RPi_BCM2835_Signals

It's not really an issue of my being right or wrong. It makes no never minds to me...

Rather, it is an issue of there being conflicting and confusing information floating around on these boards. Not a big deal, certainly not the first time or the last time, but something to be aware of.

[hippy]

That is, the SoC doesn't ever see the total input voltage; the SoC, and the rest of the on-board electronics, other than the USB, only sees the output of the first voltage regulator, which drops the input voltage down to 3V3.

I'm afraid you're wrong http://elinux.org/RPi_BCM2835_Signals

It's not really an issue of my being right or wrong. It makes no never minds to me...

Rather, it is an issue of there being conflicting and confusing information floating around on these boards. Not a big deal, certainly not the first time or the last time, but something to be aware of.

Indeed, and something that should be clarified, particularly with regards recommended and absolute maximums the SoC is rated for. At present we don't know at what voltage the SoC starts to be permanently damaged, has its life shortened, or by what amount, and we don't know at what voltage it will likely be destroyed.

For the record, from the circuit diagram - The 5V input voltage goes to SoC, USB and GPIO power pins, plus, via a diode, to the HDMI connector (+5V0_HDMI). The HDMI I2C bus is pulled-up to the 5V input voltage and diode clamped to +5V0_HDMI. That +5V0_HDMI may also be routed back to the R-Pi HDMI hot plug detection circuit when HDMI is connected.

[Larry_Adlard]

hippy wrote

For the record, from the circuit diagram - The 5V input voltage goes to SoC, USB and GPIO power pins, plus, via a diode, to the HDMI connector (+5V0_HDMI). The HDMI I2C bus is pulled-up to the 5V input voltage and diode clamped to +5V0_HDMI. That +5V0_HDMI may also be routed back to the R-Pi HDMI hot plug detection circuit when HDMI is connected.

It's quite true that 5v goes to BCM2835 into pins labelled battery. This section is labelled SMPS. Presumably, since battery operation is permitted, and battery voltages are nominal, the chip operates it's own switch mode power supply to regulate input. Clearly this would not stand up to excessive abuse but some degree of protection is built in.

With regard to life, there'll be a new model along any minute. Generally, if electronics survive the first 6 hours then they become obsolete before they "wear out."

[AndrewS]

It's not really an issue of my being right or wrong. It makes no never minds to me...
Rather, it is an issue of there being conflicting and confusing information floating around on these boards. Not a big deal, certainly not the first time or the last time, but something to be aware of.

Yeah, I was merely trying to correct the information you were providing, rather than personally calling you out for being wrong (hence the wink). Sorry if I gave the wrong impression!

[radio_cosmo]

I just got my 'Pi and was reading over magPi especially the board layout description. The input is 5 volts but right after the 5v input is a regulator that downconverts the voltage to 3.3 volts. Regulators can handle up to a certain peak voltage and generally will regulate down to within a volt of their
output. Regulators that drop below that point are called 'low voltage dropout regulators' and can
maintain regulation at voltages closer to their output. I plan to keep the mini USB in place for voltage
input but plan to tap the +5 rail and hook up to an external 5v regulator (LM7805) which can
supply 5v at an amp.
I plan to use my 'Pi for a wearable computer.
Makers moto - if you cant open it, you dont own it!
73 de Mike

[AndrewS]

input but plan to tap the +5 rail and hook up to an external 5v regulator (LM7805) which can supply 5v at an amp. I plan to use my 'Pi for a wearable computer.

Not the best idea. Presumably if you're making a wearable computer it'll be battery powered? Linear regulators (such as the venerable 7805) are cheap but very inefficient (wasting a lot of power as heat - also not good for a wearable computer!). You'd get much better battery life using a switch-mode regulator - you can get some with the same pinout as the 7805.