Thursty
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5V 5A power supply, yay or nay?

Mon Apr 30, 2018 2:33 pm

Hello guys

I'm curious, I'm building something with a Raspberry Pi 3B+, can a 5V 5A power supply be used as well?

Thank you in advance.

drgeoff
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Re: 5V 5A power supply, yay or nay?

Mon Apr 30, 2018 5:31 pm

If it meets those specs, yes. Being able to supply more current than the RPi takes is no problem.

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Re: 5V 5A power supply, yay or nay?

Mon Apr 30, 2018 5:56 pm

Except that much more smoke escapes when you manage to create a short, and not to speak of what will happen when you switch the supply on, and for a short while the output goes over 6Volt (Hint: much more smoke).
the PI should get no more than 5.1 Volt.
https://www.raspberrypi.org/help/faqs/#power

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Re: 5V 5A power supply, yay or nay?

Mon Apr 30, 2018 6:31 pm

Not sure why you would want to use a PSU that strong, but if it's well regulated (stable 5V output) it should work fine.
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Re: 5V 5A power supply, yay or nay?

Mon Apr 30, 2018 7:02 pm

HawaiianPi wrote:
Mon Apr 30, 2018 6:31 pm
Not sure why you would want to use a PSU that strong, but if it's well regulated (stable 5V output) it should work fine.
Future proofing.

For when the Pi 5 comes out, and the "official" power supply is rated that high.
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Re: 5V 5A power supply, yay or nay?

Mon Apr 30, 2018 7:29 pm

Thursty wrote:
Mon Apr 30, 2018 2:33 pm
can a 5V 5A power supply be used as well?
As noted above, providing more current than a Pi needs will not be a problem electrically but, if there's ever a short, that could cause more damage than when providing a lower current. The Pi over-current protection fuse (where included) will offer some protection so long as you use the power input connector.

But whether your supply will deliver 5A or what a Pi needs under all conditions is something you will need to test. I use a 5A supply and it is fine except it appears to current limit below 5A at turn on so causes critical low-voltage warnings during booting. That can corrupt the SD card, crash code execution, turn off ethernet, and generally cause bad things to happen.

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Re: 5V 5A power supply, yay or nay?

Mon Apr 30, 2018 8:07 pm

n67 wrote:
Mon Apr 30, 2018 7:02 pm
Future proofing.

For when the Pi 5 comes out, and the "official" power supply is rated that high.
Except that future Pi computers may actually need less power, rather than more (the current Pi models are using 40nm tech).
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Re: 5V 5A power supply, yay or nay?

Mon Apr 30, 2018 10:01 pm

HawaiianPi wrote:
Mon Apr 30, 2018 8:07 pm
n67 wrote:
Mon Apr 30, 2018 7:02 pm
Future proofing.

For when the Pi 5 comes out, and the "official" power supply is rated that high.
Except that future Pi computers may actually need less power, rather than more (the current Pi models are using 40nm tech).
I see the opposite trend. Each Pi uses more than the last (with the exception of the zero series)

Just look at the Pi3B+, even after undoing the overclocking, it still uses significantly more power than the Pi3B and frankly, is why I won't be buying one.
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Idahowalker
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Re: 5V 5A power supply, yay or nay?

Mon Apr 30, 2018 10:40 pm

Yay.

5V 5A supply, Why not? Go look at the fuse rating of the outlet that 'you' plug your RPi power supply into. My RPi power supply is currently plugged into a AC outlet that can supply up to 20 amps and the power supply to the RPi works fine. Does the RPi power supply draw 20 amps, no; but it could if it wants.

Plugging the RPi into a 5V 5 amp supply means that the RPi will draw 5 amps, no; the RPi will take what it wants and nothing more.
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Re: 5V 5A power supply, yay or nay?

Tue May 01, 2018 12:03 am

Imperf3kt wrote:
Mon Apr 30, 2018 10:01 pm
n67 wrote: Except that future Pi computers may actually need less power, rather than more (the current Pi models are using 40nm tech).
I see the opposite trend. Each Pi uses more than the last (with the exception of the zero series)

Just look at the Pi3B+, even after undoing the overclocking, it still uses significantly more power than the Pi3B and frankly, is why I won't be buying one.
Results of the past are not an indication of the future.
Up-to now all PI's used essentially the same SoC (technology), just that with the PI3 had a "CPU transplant" changing the CPU for a new quad code one, in the same technology.

The next iteration is sure to use a more frugal technology.

I would be very surprised if the next PI would consume considerably more power than the PI3B+, all that heat has to go somewhere. 5A is IMHO out of the question.

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Re: 5V 5A power supply, yay or nay?

Tue May 01, 2018 4:48 am

mahjongg wrote:
Tue May 01, 2018 12:03 am
Results of the past are not an indication of the future.
Up-to now all PI's used essentially the same SoC (technology), just that with the PI3 had a "CPU transplant" changing the CPU for a new quad code one, in the same technology.
I was under the impression that the difference between the 2837A1 (?) and the 2837B0 was mirroring the same chip and then turning it over in the package so that all the connections are in the same--relative--positions. In theory, couldn't a 2837B0 be put on a Pi3B or Pi2Bv1.2 PCB and would work? (Wouldn't get as much thermal dissipation, though.)
The next iteration is sure to use a more frugal technology.

I would be very surprised if the next PI would consume considerably more power than the PI3B+, all that heat has to go somewhere. 5A is IMHO out of the question.
I have been willing to see a 1.2GHz Pi4B. At 1.4GHz, that's just icing on the cake. So...yeah. I expect the power requirements won't go up. Whether it goes down will depend on other features.

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Re: 5V 5A power supply, yay or nay?

Tue May 01, 2018 6:22 am

mahjongg wrote:
Mon Apr 30, 2018 5:56 pm
Except that much more smoke escapes when you manage to create a short, and not to speak of what will happen when you switch the supply on, and for a short while the output goes over 6Volt (Hint: much more smoke).
the PI should get no more than 5.1 Volt.
https://www.raspberrypi.org/help/faqs/#power
FUD.

A quality power supply, whether it is rated for 2, 3 or 5A will be fine. The device will not consume more current in all cases.
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Re: 5V 5A power supply, yay or nay?

Tue May 01, 2018 7:13 am

Imperf3kt wrote:
Mon Apr 30, 2018 10:01 pm
I see the opposite trend. Each Pi uses more than the last (with the exception of the zero series).
That's because all current models are still built on 40nm tech. If the RPF wants to continue making more and more advanced $35 computers (or even cheaper computers), then that has to change. The next generation will likely be built on a smaller process node (smaller transistors) which will improve performance while reducing power consumption and manufacturing cost.

I was actually surprised they're still using 40nm (current gen Intel and AMD x86 processors are 14nm).
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Re: 5V 5A power supply, yay or nay?

Tue May 01, 2018 7:38 am

HawaiianPi wrote:
Tue May 01, 2018 7:13 am
Imperf3kt wrote:
Mon Apr 30, 2018 10:01 pm
I see the opposite trend. Each Pi uses more than the last (with the exception of the zero series).
That's because all current models are still built on 40nm tech. If the RPF wants to continue making more and more advanced $35 computers (or even cheaper computers), then that has to change. The next generation will likely be built on a smaller process node (smaller transistors) which will improve performance while reducing power consumption and manufacturing cost.

I was actually surprised they're still using 40nm (current gen Intel and AMD x86 processors are 14nm).
You are assuming the Raspberry Pi foundation intends to release a more powerful "$35 computer" for every release.
Who's to say the Pi4b is going to use 28nm tech? There has been no indication this is going to happen, so at the moment its nothing but guesswork based on assumptions created by analyzing prior trends.
I can think of several other improvements the Pi could use that don't require a faster/more efficient processor in order to use it for its intended purposes - a learning tool.
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Re: 5V 5A power supply, yay or nay?

Tue May 01, 2018 11:27 am

Not sure if it's relevant, or even rational ...

The Pi was designed to give maximum performance at a chosen price.
Since then, the price has stayed the same, with increasing performance.

But price ain't the same as cost.

Who's to say the next Pi won't have the same price and performance, but at a lower cost - more profit for the foundation to use in its charitable works?

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Re: 5V 5A power supply, yay or nay?

Tue May 01, 2018 6:04 pm

Imperf3kt wrote:
Tue May 01, 2018 7:38 am
You are assuming the Raspberry Pi foundation intends to release a more powerful "$35 computer" for every release.
That has been the case for most of the $35 price point releases.

Imperf3kt wrote:
Tue May 01, 2018 7:38 am
Who's to say the Pi4b is going to use 28nm tech? There has been no indication this is going to happen, so at the moment its nothing but guesswork based on assumptions created by analyzing prior trends.
It will be necessary to reduce both power consumption and manufacturing cost. It will have to happen someday.

But yes, it is speculation. Just like needing a 5A PSU for future generations is speculation (disregarding the fact that you can't push 5A through a micro USB connector).
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Re: 5V 5A power supply, yay or nay?

Tue May 01, 2018 10:19 pm

Imperf3kt wrote:
Tue May 01, 2018 7:38 am
Who's to say the Pi4b is going to use 28nm tech? There has been no indication this is going to happen, so at the moment its nothing but guesswork based on assumptions created by analyzing prior trends.
Nothing much... Just comments from Eben Upton and the recent hardware releases from Broadcom using a 28nm node. Certainly no clues *there*...

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Re: 5V 5A power supply, yay or nay?

Thu May 03, 2018 11:30 pm

HawaiianPi wrote:
Tue May 01, 2018 6:04 pm
Imperf3kt wrote:
Tue May 01, 2018 7:38 am
You are assuming the Raspberry Pi foundation intends to release a more powerful "$35 computer" for every release.
That has been the case for most of the $35 price point releases.

Imperf3kt wrote:
Tue May 01, 2018 7:38 am
Who's to say the Pi4b is going to use 28nm tech? There has been no indication this is going to happen, so at the moment its nothing but guesswork based on assumptions created by analyzing prior trends.
It will be necessary to reduce both power consumption and manufacturing cost. It will have to happen someday.

But yes, it is speculation. Just like needing a 5A PSU for future generations is speculation (disregarding the fact that you can't push 5A through a micro USB connector).
Are you implying that having 5A available means that I would expect the next Pi uses all of that? That is just silly. I don't. I doubt any model Pi will ever be designed to require more than 2.6A

Having 5A is beneficial, not because you'll draw it all, but because you may want 3A of it and the power supply will have a nice 2A buffer zone to avoid voltage drop.

Or you may want to power TWO Pis.

Or you may want to power a Pi and external devices.

Having a regulated 5v supply capable of 5A no longer sounds quite so fruitless, now does it?

Additionally, the micro USB spec actually has one spec for 5A @5v in it's PD range, so I expect you could deliver 5A through a microUSB connector if you use the correct hardware.
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Re: 5V 5A power supply, yay or nay?

Fri May 04, 2018 7:49 am

Imperf3kt wrote:
Thu May 03, 2018 11:30 pm
Are you implying that having 5A available means that I would expect the next Pi uses all of that? That is just silly. I don't. I doubt any model Pi will ever be designed to require more than 2.6A
I wasn't implying anything. I was just responding to n67's reply, which said:
n67 wrote:
Mon Apr 30, 2018 7:02 pm
Future proofing.

For when the Pi 5 comes out, and the "official" power supply is rated that high.
Imperf3kt wrote:
Thu May 03, 2018 11:30 pm
Additionally, the micro USB spec actually has one spec for 5A @5v in it's PD range, so I expect you could deliver 5A through a microUSB connector if you use the correct hardware.
Yes but, "if you use the correct hardware" is the problem. I know what the spec says, now show me a micro USB part that is actually rated that high.
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Re: 5V 5A power supply, yay or nay?

Fri May 04, 2018 8:12 am

A 5V 5A supply is not a problem, after all don't forget that you you are plugging it into (In the UK) a 240V 13A socket and it doesn't matter that the PI PSU doesn't need all 13A to work. The PSU only takes the power (and hence current) it needs from the mains socket.

It is the PSU output voltage level that is important, and that it is maintained as the current changes from zero the rated maximum.

So as long as the rated maximum current is greater than the peak current requirements of your PI+Peripherals all will be good :) (Terms & Conditions apply)

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Re: 5V 5A power supply, yay or nay?

Fri May 04, 2018 8:39 am

I use a variable one, 100w (20V/5A) but limited to 5A.

If you can tweak the voltages a bit, it'll be better. I can run with thick cables (4mm banana plug size) to a uUSB connector and that is where I see most the drop of my voltage, through the connectors.
Either a normal end pulled out of a cable or the usb to uUSB small convertors as they are easy to solder to.

The only thing is the Pi Zero as I think all 5A can go through the board unprotected. So a camera and high power LEDs feeding off the line make the Zero get very hot. Similar I would assume off the 5V gpio.

I'm not sure what the traces can take?

Power usage;
I think you'll find the B is quite a power draw also.

The main power user is the Ethernet chip on the Pi3 B+, don't use that and power drops down. 0.5A iirc can just be dropped using some eco setting in the gigabit Ethernet connection if in use.

Rapid.tv image, note the large lxde have for the Pi3.
But also note the B usage too.
Image


As for 40nm, they're limited to the VC4 from way back years ago. It was mentioned (ebon?) that could plug in a smaller ARM core, but it gets messy and I guess costly. Hence they use a 40nm ARM core.

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Re: 5V 5A power supply, yay or nay?

Fri May 04, 2018 6:41 pm

mahjongg wrote:
Mon Apr 30, 2018 5:56 pm
Except that much more smoke escapes when you manage to create a short, and not to speak of what will happen when you switch the supply on, and for a short while the output goes over 6Volt (Hint: much more smoke).
the PI should get no more than 5.1 Volt.
https://www.raspberrypi.org/help/faqs/#power
A properly designed regulated power supply won't surge to 6v. I made my own linear regulated psu using two 2N3055's LM723 and a crowbar for OVP. Delivers 4 amps at 5.1v, crowbar at 5.7v.

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Re: 5V 5A power supply, yay or nay?

Fri May 04, 2018 8:03 pm

I run my bread board rig off of a 5V 10A switching power supply, looks just like a laptop power supply, https://www.adafruit.com/product/658 No issues I'm aware of. I also run another Pi off of the 4A version of that supply, same deal no issues I am aware of. https://www.adafruit.com/product/1466 I have poly fuses where I think they are needed.

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