spaceman5
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The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 7:02 am

Hi all


If you look at the Raspberry Pi Zero and Zero W boards,
focusing on the Power Circuit on the right side,
There is a slight difference..


Raspbeery Pi Zero:

Image



Raspbeery Pi Zero W:

Image


Most of the components are identical, in type and even position,
but look at the Pi Zero (first picture) where it says "L1",
and look at the Pi Zero W (second picture) in the same position..

The component looks different.

Is it the same component (Inductor) in both, just in a different casing,
or a different component?


Hopefully someone got to check it out..


Thank you

laurent
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 8:05 am

Hi,
Probably due to power requirement difference between Zero and Zero W, they had to use a stronger inductor.

spaceman5
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 8:15 am

Hi laurent


Thank you for your answer.


Both boards work on 5v,
Do you know what is the required Current in the Zero vs the Zero W?

And also, do you know how much Current each of them can provide to a USB Device that is connected to the Host port?

(is there maybe a datasheet for each Raspberry Pi?)

drgeoff
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 8:23 am

spaceman5 wrote:
Fri Sep 13, 2019 8:15 am
Hi laurent


Thank you for your answer.


Both boards work on 5v,
Do you know what is the required Current in the Zero vs the Zero W?

And also, do you know how much Current each of them can provide to a USB Device that is connected to the Host port?

(is there maybe a datasheet for each Raspberry Pi?)
There is no explicit current limiter on the USB port on either the Zero or ZeroW. The power pins of the two micro-USB sockets are joined by PCB tracks. The limit will be set by the capability of the PSU or its cable or the PCB tracks burning up. No ordinary USB device should draw enough current to cause the last of those.

spaceman5
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 8:44 am

drgeoff wrote:
Fri Sep 13, 2019 8:23 am
There is no explicit current limiter on the USB port on either the Zero or ZeroW.
The power pins of the two micro-USB sockets are joined by PCB tracks.
The limit will be set by the capability of the PSU or its cable or the PCB tracks burning up.
No ordinary USB device should draw enough current to cause the last of those.
How nice..
On one hand it means no power limit,
on the other hand it means no protection, if the device for some reason has a problem like a short-circuit, and a resettable fuse would've helped..

fruitoftheloom
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 8:50 am

spaceman5 wrote:
Fri Sep 13, 2019 8:44 am
drgeoff wrote:
Fri Sep 13, 2019 8:23 am
There is no explicit current limiter on the USB port on either the Zero or ZeroW.
The power pins of the two micro-USB sockets are joined by PCB tracks.
The limit will be set by the capability of the PSU or its cable or the PCB tracks burning up.
No ordinary USB device should draw enough current to cause the last of those.
How nice..
On one hand it means no power limit,
on the other hand it means no protection, if the device for some reason has a problem like a short-circuit, and a resettable fuse would've helped..

All down to costs and what will fit on this type of PCB design.
Retired disgracefully.....
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spaceman5
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 9:17 am

I see.


BTW, there are 4 holes that we can solder pin headers to, above the inductor..
What are they for?

fruitoftheloom
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 9:32 am

spaceman5 wrote:
Fri Sep 13, 2019 9:17 am
I see.


BTW, there are 4 holes that we can solder pin headers to, above the inductor..
What are they for?

You should read the MagPi Magazine it covers a lot more than can be gleaned from making multi post in these forums:

https://www.raspberrypi.org/magpi/rca-pi-zero/

https://www.raspberrypi.org/magpi/
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alphanumeric
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 9:40 am

If the Pi was shut down and left powered up, momentarily grounding the Run pin will boot it up. You don't want to do that while its running though as it will like pushing the reset button on a PC. It will reboot on the spot without shutting down properly first.
RUN is actually the SOC Reset pin. It DOES NOT perform a safe shutdown, but can be used to restart the Pi after shutdown.
The TV pin I believe is the composite video out that would normally go out the analog audio jack, which the Zero doesn't have.
https://www.raspberrypi.org/magpi/rca-pi-zero/

spaceman5
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 10:05 am

alphanumeric wrote:
Fri Sep 13, 2019 9:40 am
If the Pi was shut down and left powered up, momentarily grounding the Run pin will boot it up. You don't want to do that while its running though as it will like pushing the reset button on a PC. It will reboot on the spot without shutting down properly first.
RUN is actually the SOC Reset pin. It DOES NOT perform a safe shutdown, but can be used to restart the Pi after shutdown.
A Power On + Reset button,
sounds dangerous :)

OK I won't use it..

alphanumeric wrote:
Fri Sep 13, 2019 9:40 am
The TV pin I believe is the composite video out that would normally go out the analog audio jack, which the Zero doesn't have.
https://www.raspberrypi.org/magpi/rca-pi-zero/
Oh,
all displays that you buy today have HDMI..
So this second pair can also be left unsoldered..

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rin67630
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 10:21 am

spaceman5 wrote:
Fri Sep 13, 2019 8:15 am
Both boards work on 5v,
Do you know what is the required Current in the Zero vs the Zero W?
The inductor is used to generate 3,3V for the processor AND, on the W the WiFi circuitry, which needs ~ 40% more current than the processor alone.
spaceman5 wrote:
Fri Sep 13, 2019 8:15 am
And also, do you know how much Current each of them can provide to a USB Device that is connected to the Host port?
This is 5V sourcing, which is not provided from the circuit involving L1.

alphanumeric
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 10:23 am

I only ever solder a header there if I'm going to use the RUN pin. For most people, yes, just leave it as is. Only populate it if your actually going to use it.

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rin67630
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 10:24 am

spaceman5 wrote:
Fri Sep 13, 2019 10:05 am
all displays that you buy today have HDMI..
No. Many displays sold for the Pi have a SPI interface.

spaceman5
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 10:25 am

Thank you both.

rin67630 wrote:
Fri Sep 13, 2019 10:21 am
The inductor is used to generate 3,3V for the processor AND, on the W the WiFi circuitry,
which needs ~ 40% more current than the processor alone.
How much mA each consumes, from your measurements?

rin67630 wrote:
Fri Sep 13, 2019 10:21 am
This is 5V sourcing, which is not provided from the circuit involving L1.
Good point..

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rin67630
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 11:22 am

spaceman5 wrote:
Fri Sep 13, 2019 10:25 am
How much mA each consumes, from your measurements?
AFAIR, headless, the Zero draws a 5,2 V 80mA idle, the ZeroW 120mA with an active WiFi connection in 5 meter range.
The figures are worse, if you connect a USB hub...

spaceman5
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 11:27 am

Wow 80mA that's so little..

My Zero and Zero W boards should arrive in 2 days,
would be interesting to do some measurements

fruitoftheloom
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 11:46 am

spaceman5 wrote:
Fri Sep 13, 2019 11:27 am
Wow 80mA that's so little..

My Zero and Zero W boards should arrive in 2 days,
would be interesting to do some measurements

https://www.raspberrypi.org/documentati ... /#pi-power

Everything discussed has nigh on 4 years worth of relevant blogs, tutorials, how-tos et-al.....

https://www.raspberrypi.org/blog/raspberry-pi-zero/

https://www.raspberrypi.org/blog/raspbe ... ns-family/
Retired disgracefully.....
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spaceman5
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 1:19 pm

That FAQ page was terrific,
so much useful information, thank you very much..

W. H. Heydt
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 4:08 pm

spaceman5 wrote:
Fri Sep 13, 2019 1:19 pm
That FAQ page was terrific,
so much useful information, thank you very much..
Now you know why one of the oldest replies to computer questions is: RTFM.

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rin67630
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 4:35 pm

spaceman5 wrote:
Fri Sep 13, 2019 11:27 am
Wow 80mA that's so little..
I've done the measurements.
But remember: 80mA is just the bare Zero running at 700MHz with ~20% CPU using a 8GB SD card.
I use them with a GPIO serial link. The USB serial link will draw 30mA more!
Even a USB mouse/keyboard will increase the power requirements significantly.
As soon as you add video and USB hubs/peripherals, you will need more!

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FTrevorGowen
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 5:12 pm

rin67630 wrote:
Fri Sep 13, 2019 4:35 pm
spaceman5 wrote:
Fri Sep 13, 2019 11:27 am
Wow 80mA that's so little..
I've done the measurements.
But remember: 80mA is just the bare Zero running at 700MHz with ~20% CPU using a 8GB SD card.
I use them with a GPIO serial link. The USB serial link will draw 30mA more!
Even a USB mouse/keyboard will increase the power requirements significantly.
As soon as you add video and USB hubs/peripherals, you will need more!
Have you tried powering via the USB-to-Serial device? It is possible (for the zero and some USB-to-Serial devices) :
http://www.cpmspectrepi.uk/raspberry_pi ... Powered.22
http://www.cpmspectrepi.uk/raspberry_pi ... es_Only.29
Trev.
Still running Raspbian Jessie or Stretch on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W, 2xP3A+, P3B+, P3B, B+, A+ and a B2) but Buster on the P4B's. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

spaceman5
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Fri Sep 13, 2019 5:25 pm

Really nice..

Since the board is powered with 5v and not 3.3v,
then this does not depend on the Serial Adapter's Voltage Converting capabilities (if any exists even)..

Some have an LDO to convert from 5v to 3.3v, and some use FTDI's "3.3VOUT" leg (leg #17) which gives only 50mA,
but here's it's not relevant and not a problem at all, it only depends on the USB Host socket that the Serial Adapter is connected to.

pollard5
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Sat Sep 14, 2019 6:36 am

Maybe because of the Power difference between Zero and Zero W they are using a strong inductor.

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rin67630
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Re: The Power Circuit in Pi Zero vs Pi Zero W

Sat Sep 14, 2019 8:00 am

FTrevorGowen wrote:
Fri Sep 13, 2019 5:12 pm
rin67630 wrote:
Fri Sep 13, 2019 4:35 pm
I use them with a GPIO serial link. The USB serial link will draw 30mA more!
Have you tried powering via the USB-to-Serial device?
Why considering USB and adapters?
The host (when connected) is a Pi3B and I connect using the GPIO.

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